Dynamic semiconductor diode generators (DDGs) offer a potential portable and miniaturized energy source, with the advantages of high current density, low internal impedance, and independence of the rectification circuit. However, the output voltage of DDGs is generally as low as 0.1–1 V, owing to energy loss during carrier transport and inefficient carrier collection, which requires further optimization and a deeper understanding of semiconductor physical properties. Therefore, this study proposes a vertical graphene/silicon DDG to regulate the performance by realizing hot carrier transport and collection. With instant contact and separation of the graphene and silicon, hot carriers are generated by the rebounding process of built‐in electric fields in dynamic graphene/silicon diodes, which can be collected within the ultralong hot electron lifetime of graphene. In particular, monolayer graphene/silicon DDG outputs a high voltage of 6.1 V as result of ultrafast carrier transport between the monolayer graphene and silicon. Furthermore, a high current of 235.6 nA is generated due to the carrier multiplication in graphene. A voltage of 17.5 V is achieved under series connection, indicating the potential to supply electronic systems through integration design. The graphene/silicon DDG has applications as an in situ energy source for harvesting mechanical energy from the environment. The vertical graphene/silicon dynamic diode generator (DDG) is proposed and the detailed hot carrier dynamics are explored. High voltage of 6.1 V and current of 235.6 nA are achieved in monolayer graphene/silicon DDG unit, attributing to ultrafast carrier transport and carrier multiplication in graphene. This work provides a novel and potential in situ source for harvesting mechanical energy from the environment. Among these clean energy technologies, mechanical energy is one of the most abundant energy sources with no time and geographical location limitations, and is usually harvested by electromagnetic generators. However, electromagnetic generators require electromagnetic windings and permanent magnets, for which miniaturization and wearable integration are major challenges. Meanwhile, the recently developed dynamic semiconductor diode generator (DDG) is a good candidate for a miniaturized, portable, integrated, and renewable micro generator, able to harvest low‐frequency mechanical energy. Furthermore, the rise of the Internet of Things (IoTs) and wearable electronic devices presents new demands for in‐situ energy and sensors, including miniaturization, high power density, lightness, integration, portability, and flexibility. The DDG has significant advantages that meet the requirements of IoTs devices, including high current density, low internal impedance matching with semiconductor based electron devices, no storage or external circuit restrictions, and continuous and stable power generation.The global development of “carbon neutral” strategies presents new energy demands,1 ther semiconductor‐semiconductor, metal‐semiconducting polymer, and liquid‐semiconductor structure generators. However, the voltage performance of vertical DDGs is inferior owing to energy loss during carrier transport and collection, which is usually as low as 0.1–1V and requires further enhancement for wider applications. Under the semiconductor physics framework, the electrical energy conversion phenomenon is attributed to the dynamic equilibrium of the semiconductor depletion region and carrier rebounding at the interface during mechanical movement. The rebounding electrons and holes in the dynamic semiconductor depletion region are separated and accelerated by the built‐in electric field at the interface, generating hot carriers with high energy. However, owing to the energy loss during the carrier transport and inefficient carrier collection in the semiconductor, high energy hot carriers excited by mechanical input and the built‐in electric field are difficult collect effectively in traditional DDG structures, leading to an inferior voltage and current performance. In contrast to the accumulated charges in polymer‐based generators, rebounded hot carriers in semiconductor‐based generators can instantaneously rebound and accelerate from the interface to electrodes. However, it remains a challenge to collect and utilize the rebounding hot carriers in dynamic semiconductor diodes, which is vital to enhance the performance of DDGs. Furthermore, the detailed carrier dynamics of a dynamic semiconductor junction require further detailed investigations, including the establishment, dynamic equilibrium and destruction processes.The structure and physical characteristics of DDGs have been widely explored, including the dynamic metal‐semiconductor,10 sem The most attractive attributes of graphene are the ultralong hot electron lifetime and linear energy dispersion, which are attributed to the strong in‐plane electron‐electron interactions. Therefore, graphene is an ideal model structure for the study of hot carrier transport and carrier multiplication, which are inefficient in conventional semiconductor. The properties of layered graphene/silicon Van der Waals heterojunctions provide a new structure for exploring hot carrier generation and transport in dynamic semiconductor diodes. Therefore, this study proposes a vertical graphene/silicon DDG, and the detailed hot carrier dynamics of the graphene/silicon interface are explored. To systematically explore the hot carrier dynamic processes of the vertical graphene/silicon DDG, the entire generation, transport, and collection processes of hot carriers are illustrated, which reveal how the hot carriers of graphene in dynamic heterojunction interfaces can be effectively utilized. When the graphene and silicon are in vertical contact, electrons diffuse from the higher Fermi level graphene to the lower Fermi level silicon and form a static depletion region in the microsecond time scale, generating a voltage as high as 1.5 V. Following the vertical separation of the graphene and silicon, the dynamic equilibrium of the depletion region is disrupted and diffusion carriers are released and rebound to graphene and silicon, generating an opposite voltage output. The voltage is significantly higher than the barrier height of the graphene/silicon heterojunction. Therefore, hot carriers generated within the rebounding process caused by the built‐in electric field in dynamic graphene/silicon diodes can be collected.As a 2D material, graphene has significant advantages of excellent carrier mobility, a zero band gap, and superconductivity.17 The which increases the efficiency of hot carrier collection with vertical graphene/silicon DDGs. To further reduce the energy loss of hot carriers, monolayer graphene is applied, achieving a voltage as high as 6.1 V and a current as high as 235.6 nA have been achieved, which provides further evidence for the effective utilization of hot carriers. Specifically, the enhanced voltage is attributed to the ultrafast hot carrier transport in monolayer graphene/silicon Van der Waals heterojunctions and the enhanced current is attributed to the carrier multiplication during the Auger process of graphene. Furthermore, a voltage as high as 17.5 V is achieved by series connection, which is high enough to power portable electronic systems in typical scenarios, indicating the potential of the generator chip inside a self‐powered electronic system through integration design. Although the Van der Waals interaction between the silicon and graphene is strong, the vertical graphene/silicon DDG shows excellent stability and durability, with no obvious voltage attenuation and limited interface damage after working for 1h. This indicates that the vertical graphene/silicon DDG has practical applications with high reliability. This study on the carrier kinetics of a vertical graphene/silicon DDG provides interesting details on DDG electrical properties, highlighting their application as novel and potential in‐situ energy sources for harvesting mechanical energy from the environment. Furthermore, the effective utilization of hot carriers in graphene/silicon DDGs paves the way for further enhancement of the electrical performance of other DDGs.To further enhance the electrical performance of the vertical graphene/silicon DDG, several factors influencing the physical processes are systematically investigated, such as resistivity, work area, and applied force. Compared to metal and silicon substrates, graphene has the unique advantage of an ultralong hot electron lifetime in graphene/silicon Van der Waals heterojunctions,21 whi2Graphene has attracted significant attention in the field of electronic devices, especially in wearable devices. In preliminary work, considering high conductive and high mechanical physical properties, a graphene membrane was chosen to fabricate a horizontal dynamic Schottky diode generator with a superior working lifetime and flexibility, which could be used to harvest low‐frequency disordered mechanical motion into electricity. There are two general modes of mechanical motion in nature: horizontal and vertical. Compared to the horizontal mode, the vertical mode is more common in human motion, such as walking and muscle vibration. In order to effectively harvest these low‐frequency disordered vertical mechanical motions and investigate the detailed carrier dynamics processes of a dynamic semiconductor diode, a vertical graphene/silicon dynamic diode was explored. This vertical dynamic semiconductor diode can accurately transfer the irregular, low‐frequency, and weak mechanical force in the vertical direction into electrical energy.Figure As shown in the optical picture in  With the establishment of the equilibrium between the diffusion and drift currents in the graphene/silicon van der Waals heterojunction, an electron depletion region was formed in the surface of P‐type silicon substrate. Therefore, in the contacting state, a voltage as high as 1.5 V and a current as high as 122.3 nA from silicon to graphene were achieved, as shown in the vertical contact section in Figure A detailed 3D diagram and schematic structure of the vertical dynamic graphene/silicon heterojunction diode are illustrated in Figure 22 WitAfter the graphene membrane completely contacted with the P‐type silicon substrate, a stable depletion layer was established at the interface of the graphene/silicon heterojunction without an external current, in the contacted state. Then, the graphene membrane separated with p‐type silicon under the external force, the electron depletion region disappeared at the surface of the P‐type silicon substrate, and the electrons and holes diffused back to the graphene and silicon substrate, forming a positive pulse voltage/current. In this separating state, a voltage as high as 2.1 V and a current as high as 64.3 nA from graphene to silicon were achieved, as shown in the vertical separate section in Figures Figure In order to further explore the physical mechanisms of the vertical graphene/silicon DDG in a systematic semiconductor theoretical framework, the entire establishment, quasi‐dynamic equilibrium, and destruction processes of the interface depletion layer were explored, which played a key role in electricity generation. The work functions of graphene and P‐type silicon were 4.60 and 5.12 eV, respectively. Therefore, the Fermi level of the P‐type silicon substrate was lower than the graphene membrane, and the carrier distribution and energy band diagram before graphene and silicon contacting were shown in the separated state in  Figure I–V curve of the vertical graphene/silicon heterojunction DDG in the quasi‐dynamic equilibrium state, indicating the formation of the depletion region during the contact of the graphene membrane and silicon substrate, which can achieve ideal rectification characteristics with limited leakage under a negative bias voltage.After the graphene membrane and silicon substrate were in stable contact, a quasi‐dynamic equilibrium was established in the graphene/silicon heterojunction, where the diffusion and drift current cancelled each other out. In this dynamic balanced heterojunction, no current flowed through the heterojunction with the external circuit, where the energy band structure was shown in the contacted state. However, when the graphene membrane and silicon substrate were separated under mechanical force, the diffused electrons/holes that had been trapped in the space charge area of heterojunction were released and rebounded to the graphene membrane/silicon through the external circuit, generating a current from the graphene membrane to the silicon substrate. The detailed carrier distribution and energy band diagram of the dynamic graphene/silicon diode in this separating process is shown in the separating state. In the repeatable contact and separate cycles of the vertical graphene/silicon DDG, the electrons and holes in the graphene membrane and silicon substrate were diffused and rebounded between the graphene and silicon with the dynamic equilibrium of the depletion region. In contrast to the traditional triboelectric nanogenerator based on a displacement current, a conduction current across the graphene/silicon heterojunction was involved in generating power, leading to an ultrafast response time.23 FigFurthermore, to quantitatively reveal the relationship between the voltage output and the Fermi level difference, as well as the interface barrier of the dynamic graphene/silicon diode, a series of P‐type silicon substrates with different resistivity of 0.001, 0.01, 0.5, 3, 10, and 50 Ω cm were explored. The Fermi level of the P‐type silicon was calculated using the following equations:24, G‐peak (1584 cm−1), and 2D‐peak (2724 cm−1). The low intensity ratio between the 2D‐peak and G‐peak indicates the graphene membrane was multilayer. In particular, the weak D‐peak showed the high quality and limited crystal defects of the graphene membrane, which contributed to the limited carriers recombination and effective collection of the rebounding hot carriers in the vertical graphene/silicon DDG. To systematically explore the electrical properties of the vertical graphene/silicon heterojunction DDG, the voltage and current with different contact areas or forces were measured. As shown in Figure 2, which can be further improved by interface array design.In the hot carrier generation and transport processes, the graphene membrane plays a key role in hot carrier transport and collection. The Raman spectrum of the graphene membrane at a room temperature of 25°C was measured, as shown in membrane,25 whi3 was selected as an intercalation of the graphene membrane, which could export the electrons in the graphene layer. As shown in the Raman spectrum of the graphene membrane with FeCl3 doping in Figure 3 resulted in a P‐type doping and downward Fermi level for the graphene. This P‐type doping of graphene decreased the barrier height of the graphene/silicon heterojunction, leading to a directional and quantitative adjustment of the voltage output through further changes in concentration, as shown in Figure Furthermore, the relationship between the voltage and current output with different applied forces was also explored, as shown in Figure To address the universality of this vertical dynamic diode generator, a series of different semiconductor structure diodes were also measured. Compared with the vertical graphene/P‐type silicon DDG, an opposite voltage direction was observed for the vertical graphene membrane/N‐type silicon DDG, as the Fermi level of the graphene membrane was lower than the N‐type silicon. Figure In addition to the dynamic graphene/silicon heterojunction, vertical Al/P‐type silicon and N‐type/P‐type silicon DDGs were explored. As shown in Figure Figure To optimize the electrical performance and further develop the detail hot carrier transport mechanism of the vertical graphene/silicon DDG, few‐layer graphene was applied. As shown in As shown in Figure In addition to the investigation of the monolayer graphene/P‐type silicon DDG, different layers of graphene were also studied. Bilayer, trilayer and thin graphene film were used to perform the same contact and separate experiments. As shown in Figure VL) and work current (IL) outputs as a function of electrical load resistance (RL) were measured, as shown in Figure RS) was calculated with the different load resistance matching method, in which the power output achieved a maximum peak. The corresponding power output was controlled by the work voltage and work current, which was calculated as a product of the voltage and current. As shown in Figure Finally, to quantitatively demonstrate the power output of the vertical graphene/silicon DDG, the work voltage  to avoid short circuiting. The thickness of the graphene membrane and the Al film was 40 µm. Furthermore, single side polished N‐type and P‐type doped silicon substrates were used, which were dipped into 10 wt% HF for 5 min to remove the native silicon oxide layer. The resistivity of P‐type and N‐type silicon was 0.5 Ω cm. The Ti/Au (5 nm/50 nm) electrode of the N‐type or P‐type silicon was grown using the magnetron sputtering method on the unpolished back side, which formed an ohmic contact after annealing in inert gas at a temperature of 400 °C. The monolayer, bilayer, and trilayer graphene were grown using the chemical vapor deposition (CVD) method and then transferred to a PET substrate. The graphene membrane was contacted and separated with the silicon substrate by a constant external force, ensuring a uniform surface contact in the vertical graphene/silicon DDG.I–V) data. A Keithley 6514 system electrometer and DMM6500 multimeter were used to record the real time voltage and current responses of the vertical graphene/silicon DDG, which were controlled by a LabView‐based data acquisition system with a sampling rate of 10 000 s−1. The Raman spectrum of the graphene membrane was measured using the Renishaw inVia Reflex under an excitation laser , which was focused on a circle with a radius of 1 mm.The image of the graphene membrane was recorded using a high definition camera. SEM images of the graphene membrane were recorded using a HITACHI S‐4800 system. Keithley 2400 and Agilent B1500A systems were used to record the current–voltage (The authors declare no conflict of interest.S.L. designed the experiments, analyzed the data, and conceived the study. Y.L. designed and carried out the experiments, discussed the results, and wrote the paper. R.S., X.Y., Y.Y., H.Z. Y. Y., C.L., Z.Y., L.F., and L.L. discussed the results and assisted with experiments. All authors contributed to the preparation of the manuscript.Supporting InformationClick here for additional data file.


CHCHD10, a gene coding for a mitochondrial intermembrane space protein, are associated with Frontotemporal dementia (FTD)-Amyotrophic lateral sclerosis (ALS) spectrum disorders, which are pathologically characterized by cytoplasmic inclusions containing TDP-43. FTD/ALS-linked CHCHD10 mutations and TDP-43 inclusions similarly induce mitochondrial defects in respiration, fusion/fission, mtDNA stability, and cristae structure, while sizeable amounts of cytoplasmic TDP-43 aggregates are found in mitochondria. However, the mechanistic link between CHCHD10 and TDP-43 pathogenesis remains unclear. In this study, we present immunohistochemical and biochemical evidence demonstrating that insoluble CHCHD10 aggregates accumulate and colocalize with phospho-TDP-43 inclusions in brains of FTLD-TDP and AD patients, and that insoluble CHCHD10 levels tightly correlate with insoluble TDP-43 levels in control and FTLD-TDP brains. In an experimental exploration of this pathological phenotype, transgenic mice neuronally expressing FTD/ALS-linked CHCHD10R15L or CHCHDS59L mutations but not CHCHD10WT transgenic mice exhibit significantly increased CHCHD10 aggregation and phospho-TDP-43 pathology, which often colocalize within the same inclusions. Such pathologies are reflected in poor functional outcomes in long-term synaptic plasticity, motor unit physiology, and behavior in CHCHD10R15L and CHCHDS59L transgenic mice. In contrast, expression of CHCHD10WT in hTDP-43 transgenic mice  significantly mitigates phospho-TDP-43 pathology and rescues TDP-43-induced impairments in synaptic integrity and long-term synaptic plasticity. In isolated mitochondria, the S59L mutation induces the aggregation of resident CHCHD10S59L protein as well as the aggregation and slower turnover of recombinant TDP-43 imported into mitochondria. Likewise, in an in vitro cell-free system, the S59L mutation induces the aggregation of CHCHD10S59L protein while simultaneously enhancing the aggregation of recombinant TDP-43, as evidenced by filter trap assays and atomic force microscopy. In contrast, recombinant CHCHD10WT inhibits the growth of TDP-43 aggregates. These results in human brains, transgenic mice, and in vitro systems substantiate the role of wild type and mutant CHCHD10 in modulating mitochondrial CHCHD10 and TDP-43 pathogenesis together with associated phenotypes in long-term synaptic plasticity and motor unit physiology in mice and humans.Mutations in The online version contains supplementary material available at 10.1186/s40478-022-01386-9. The spectrum of Frontotemporal dementia (FTD) and Amyotrophic lateral sclerosis (ALS) disorders share multiple genetic and pathological etiologies. Specifically, proteopathic inclusions containing the TAR DNA binding protein-43 (TDP-43) represent the common pathological hallmark of FTD-ALS spectrum disorders –3. TDP-4Coiled-coil-helix-coiled-coil-helix domain containing 10 (CHCHD10) encodes a small 15-kDa mitochondrial intermembrane space (IMS) protein, in which multiple mutations have been linked to the etiology of both sporadic and familial FTD-ALS spectrum disorders . I. I43]. IR15L and CHCHD10S59L mice exhibited severely reduced MUNE  compared to WT and CHCHD10WT mice  and innervates most of the hind limb. In 10-month-old mice, we carried out in vivo recordings at the gastrocnemius muscle after stimulation of the sciatic nerve using the incremental motor unit number estimation (MUNE) method  littermates. At 10 months of age, TAR4;D10WT mice did not alter full-length human 43-kDa TDP-43 levels in the RIPA-soluble fraction compared to littermate TAR4 mice, although significant ~ 60% reductions in both the 25-kDa and 35-kDa TDP-43 fragments were observed in TAR4;D10WT mice compared to TAR4 mice , intermembrane space, (IMS), inner membrane (IM), and matrix. As shown in preceding results, Flag-CHCHD10WT was highly enriched in the IMS [WT mitochondria, however, TDP-43 was generally reduced in mitochondria and absent in fractions where Flag-CHCHD10WT was most enriched (IMS & matrix)  exhibit significantly reduced level of soluble CHCHD10 protein , suggestpromoter  with hem the IMS  with minWT littermates. Hemizygous TAR4 mice exhibited significantly reduced immunoreactivity for synaptic markers synaptophysin in the CA3 region of the hippocampus compared to WT mice, which was completely rescued to or beyond WT levels in TAR4;D10WT mice  at the expense of the low-height material  mitigates TDP-43 pathology and rescues TDP-43-induced deficits in long-term synaptic plasticity in vivo. These results overall implicate CHCHD10-mediated modulation of TDP-43 aggregation in mitochondria as a significant factor contributing to impairments in long-term synaptic plasticity and motor unit function.TDP-43 inclusions are pathologically evident in more than 95% of ALS, ~ 50% of FTD (FTLD-TDP variant), and > 50% of late-onset AD , 9. As onic mice  and CHCHS59L significantly increases TDP-43 aggregation upon import is consistent with the accumulation of TDP-43 in mitochondria in CHCHD10R15L and CHCHD10S59L transgenic primary neurons and brains in vivo. These results are also consistent with a recent study showing that the CHCHD10S59L mutation increases insoluble mitochondrial TDP-43 in transfected HeLa cells [CHCHD10 mutation to date (p.R15L) [CHCHD10 mutations. Our findings from FTLD-TDP and AD cases showing robust colocalization phospho-TDP-43 pathology with CHCHD10 inclusions (~ 75–84%) and tight correlation between insoluble CHCHD10 with insoluble TDP-43 indeed indicates a pathological link between them in human neurodegenerative diseases. Beyond TDP-43-related spectrum disorders, our mechanistic model may also help to shed light on the diversity of disease phenotypes associated with CHCHD10 mutations, such as mitochondrial myopathy [Mitochondrial targeting of misfolded or aggregation-prone proteins from the cytosol has recently been proposed as a pathway to handle and turnover misfolded proteins within mitochondria, which otherwise would overwhelm the cytosolic proteostasis machinery . This miLa cells . While tLa cells , our res(p.R15L) . In this(p.R15L) . In thismyopathy , spinal myopathy , and Chamyopathy . In suchWT under pathological conditions, perhaps through excessive mitochondrial translocation of TDP-43 (i.e. FTLD-TDP or AD). In this scenario, the loss of functional CHCHD10 or gain of misfolded CHCHD10 fails to oppose or directly promotes TDP-43 aggregation, respectively, thereby generating a maladaptive feed-forward cycle of mitochondrial proteinopathy. This notion is supported by the observation that insoluble TDP-43 positively correlates with insoluble CHCHD10 in human brains. Accumulation of TDP-43 and mutant CHCHD10 in mitochondria are damaging to mitochondria and neurons that house them [S59L-mediated toxicity [The propensity for mutant CHCHD10 to misfold and aggregate per se represents a gain-of-function molecular phenotypes intrinsic to its protein structure , 35. We use them , 26, andtoxicity . Hence, R15L and CHCHD10S59L transgenic models used in this study faithfully recapitulated many pathological phenotypes associated with FTD-ALS. These included CHCHD10 pathology and increased pTDP-43 levels associated with deficits in synaptic integrity, long-term synaptic plasticity, motor unit physiology, sciatic nerve action potential velocity, and motor behavior. Deficits in MUNE indicated loss of the functional connectivity between motor neurons and muscle, one of the key features of motor neuron disease [R15L mice [R15L and CHCHD10S59L mice. As mitochondrial health and transport is crucial to sustain synaptic function at both sides of the synapse [R15L and CHCHD10S59L mice indicated reduced ability to sustain synaptic efficacy, a phenotype tied to learning and memory [WT in TDP-43 transgenic mice (TAR4) fully rescued synaptic integrity and LTP deficits induced by TDP-43, which was underpinned by significantly reduced TDP-43 pathology in TAR4;D10WT mice. These transgenic models, which express CHCHD10 variants under the control of neuron-specific mouse PrP promoter and correctly target to the IMS of mitochondria, therefore, represent useful tools to study CHCHD10 function and dysfunction originating from neurons of the CNS. Other reported models such as the CHCHD10S55L knock-in mouse model driven by the endogenous mouse CHCHD10 promoter [R15L expression with human CHCHD10 promoter [The CHCHD10 disease –46. Sign15L mice . These e synapse –40, defid memory . It is npromoter , 35 and promoter  exhibit Additional file 1. CHCHD10 aggregates and TDP-43 inclusions in FTLD-TDP and AD patients’ brains. (a) Information describing human brain tissue from normal, FTLD-TDP43 and AD patients used for immunohistochemistry. (b) Representative blots of pS409/410-TDP-43, and actin from RIPA-insoluble frontal cortex brain extracts. (c) Quantification of RIPA-insoluble pS409/410-TDP-43 from human FTLD-TDP and nondemented control frontal cortex .Additional file 2. FTD/ALS-linked CHCHD10 mutations drive CHCHD10 insolubility and TDP-43 aggregation in vivo and in cultured cells. (a) Mitochondria isolated from 10-month-old D10WT mouse brains sub-fractionated for outer membrane (OM), intermembrane space (IMS), inner membrane (IM) and matrix and then immunoblotted for hTDP-43, Flag-CHCHD10 (M2), Tom20, mitofilin, and ClpP. Known sub-mitochondrial localization of indicated proteins in parenthesis. (b) Quantification of Flag-CHCHD10 from sub-fractionated mitochondria . (c) Representative frontal cortex images of 10-month-old CHCHD10WT , CHCHD10R15L and CHCHD10S59L mice immunotained for CHCHD10 (red), NeuN (green) and DAPI (blue). (d) Negative control staining of CHCHD10-WT brain without primary antibody but with secondary antibody and DAPI. (e) RIPA-soluble extracts from the cortex of 10-month-old WT, CHCHD10WT, CHCHD10R15L, and CHCHD10S59L mice immunoblotted for Flag-M2 (Flag-CHCHD10) and actin. (f) Representative frontal cortex images of 10-month-old CHCHD10S59L mice immunostained for Flag-CHCHD10 (green), pS409/410-TDP-43 (red), and DAPI (blue). Panels to the right show negative controls without primary antibodies but with secondary antibodies and DAPI. (g) Equal amounts of sonicated RIPA-insoluble pellets from 10-month-old CHCHD10WT, CHCHD10R15L, and CHCHD10S59L mice subjected to filter trap assay for TDP-43. (h) Quantification of captured TDP-43 aggregates from figure (S2g) =11.81, P=0.0082, posthoc Tukey, *p<0.05, **p<0.01, n=3 mice/genotype). (i-j) Tet-inducible Hela-myc-TDP-43 cells transfected with Flag-CHCHD10WT, Flag-CHCHD10R15L, or Flag-CHCHD10S59L for 48h and subjected to (i) immunoblotting for Flag-CHCHD10 and actin from RIPA-soluble and RIPA-insoluble lysates and (j) filter-trap assay for CHCHD10 and TDP-43 from sonicated RIPA-insoluble pellets. (k) Quantification of captured TDP-43 aggregates from figure (S2j) =51.65, P=0.0002, posthoc Tukey, #p<0.001, n=3/group)Additional file 3. Gliosis in WT, CHCHD10WT, CHCHD10R15L, and CHCHD10S59L mice. (a) Representative images of brain sections from 10-month-old WT mice immunostained for synaptophysin (red). Negative controls without primary antibody but with secondary antibody and DAPI in the right panels.  Representative images of brain sections from 10-month-old WT, CHCHD10WT, CHCHD10R15L, and CHCHD10S59L mice immunostained for GFAP (green), Iba1 (red), and DAPI (blue).  Quantification of GFAP and Iba1 intensities from figure (S3b) (1-way ANOVA: (e) F=34.18, P<0.0001, posthoc Tukey, *p<0.05, #p<0.001, ##p<0.0001, F=0.5214, P=0.6685; n=22-28 sections/genotype from 4 mice/genotype)Additional file 4. Increased TDP-43 pathology in the spinal cord of CHCHD10R15L and CHCHD10S59L mice. (a) Representative images of lumbar spinal cord sections from 10-month-old WT, CHCHD10WT, CHCHD10R15L, and CHCHD10S59L mice immunostained for Flag-CHCHD10 and ChAT. (b) Representative images of lumbar spinal cord sections from 10-month-old CHCHD10WT, CHCHD10R15L, and CHCHD10S59L mice immunostained for pS409/410-TDP-43 (green) and DAPI (blue). White boxes magnified in bottom panels. (c) Quantification of pS409/410-TDP-43 intensity from figure (S4b) =11.52, ##P<0.0001: posthoc Tukey, #p<0.0005, n=23-24 images/genotype from 4 mice/genotype)Additional file 5. CHCHD10WT mitigates TDP-43 pathology in spinal cord of TDP-43 transgenic mice. (a) Representative images of brains section from 10-month-old TAR4;D10WT mice immunostained for hTDP-43 (green), CHCHD10 (red), and DAPI (blue) in the left panel. Negative control without primary antibodies but with secondary antibodies and DAPI in the right panel. (b) Representative images of brains section from 10-month-old TAR4 mice immunostained for pS409/410-TDP-43 (green) and DAPI (blue) in the left panel. Negative control without primary antibody but with secondary antibody and DAPI in the right panel. (c) Representative images of lumbar spinal cord sections from 10-month old TAR4 and TAR4;D10WT mice immunostained for hTDP-43 (green), CHCHD10 (red) and DAPI (blue). White boxes magnified in right panels. (d) Quantification of cytoplasmic to nuclear TDP-43 intensity ratio from figure (S5c) . (e) Representative images of lumbar spinal cord sections from 10-month-old TAR4 and TAR4;D10WT mice immunostained for human pS409/410-TDP-43 (green) and DAPI (blue). White boxes magnified in right panels. (f) Quantification of pS409/410-TDP-43 intensity from figure (S5e) Additional file 6. Short-term synaptic efficacy in WT, TAR4 and TAR4;D10WT mice. Acute brain slices from 10-month-old TAR4 and TAR4;D10WT mice subjected to Input/Output (I/O) measurements by stepping up stimulation amplitude from 0.5 to 18mV =49.95, P<0.0001, posthoc Tukey, *p<0.05 , not significant for other mVs among genotypes, n=24-58 slices/genotype from 3-5 mice/genotype)Additional file 7. Increased mitochondrial accumulation of TDP-43 by FTD/ALS-linked mutations in vivo and primary neurons. (a) Isolated mitochondria from 10-month-old CHCHD10WT, CHCHD10R15L, and CHCHD10S59L mice immunoblotted for CHCHD10, TDP-43, and Tom20. (b) Quantification of the mitochondrial TDP-43 from figure (S7a) =26.43, P=0.0011: posthoc Tukey, *p<0.05 #p<0.001, n=3 mice/genotype). (c) Representative images of cortical primary neurons derived from WT, CHCHD10WT, CHCHD10R15L, and CHCHD10S59L mice transduced with TDP-43-tomato-HA AAV9 on DIV7, immunostained for human Tom20 (green), and subjected to direct immunofluorescence for TDP-43-tomato (red) on DIV21. White boxes magnified in bottom panels. (d) Quantification of cytoplasmic TDP-43-tomato colocalized with Tom20 from figure (S7c) =27.1, P<0.0001: posthoc Tukey, *p<0.05, #p<0.001, ##p<0.0001, n=5-15 images/genotype)Additional file 8. Purification of recombinant CHCHD10WT and CHCHD10S59L. Representative Coomassie blue stain of CHCHD10WT and CHCHD10S59L proteins purified from E. Coli.


For the developed DS diode, we obtained η < 1 for more than four decades of drain current (ηave_4dec < 1) with a minimum value of 0.8, and a rectifying ratio exceeding 108. The realisation of a DS diode represents an additional step towards the development of low-power electronic circuits.An increase in power consumption necessitates a low-power circuit technology to extend Moore’s law. Low-power transistors, such as tunnel field-effect transistors (TFETs), negative-capacitance field-effect transistors (NC-FETs), and Dirac-source field-effect transistors (DS-FETs), have been realised to break the thermionic limit of the subthreshold swing (SS). However, a low-power rectifier, able to overcome the thermionic limit of an ideality factor (η) of 1 at room temperature, has not been proposed yet. In this study, we have realised a DS diode based on graphene/MoS 8 at room temperature.While different types of low-power transistors have been investigated, low voltage rectifiers able to overcome the thermionic limit have not been proposed yet. Here, the authors report the realization of Dirac-source diodes based on graphene/MoS2/graphite heterostructures, showing ideality factors <1 and rectifying ratios exceeding 10 Reducing power consumption has been thwarted by fundamental limits on the operating voltage set by thermionic emission2. For an ideal thermionic device, the dependence of current I on voltage V is expressed through the subthreshold swing SS = [dlog10(I)/dV]−1 = (kBT/q)log(10) ≈60 mV/dec at room temperature, where kBT is the thermal energy and q is the elemental charge.Power consumption of integrated digital devices sets the ultimate limit to downscaling and Moore’s Law4 have been proposed for various schemes to overcome the thermionic limit (SS = 60 mV/dec) of metal-oxide-semiconductor field-effect transistors (MOSFETs) in nonconventional transistors such as TFETs, NC-FETs, and DS-FETs14. In particular, DS-FETs use the linear energy dispersion relationship of graphene, producing a super-exponential change in the DOS with energy15. As a result, DS-FETs have achieved a smaller SS than that of a MOSFET, with a large drive current14.Two-dimensional (2D) van der Waals (vdW) materials16, and have many useful applications such as rectifiers, mixers, selectors, switches, photodetectors and solar cells16. Although there has been considerable development of low-power transistors, steep-slope diode (or triode) rectifiers that overcome the thermionic limit (η < 1) of conventional diodes have not been proposed yet, but will be necessary for device integration with low-power transistors. Herein, we propose a DS diode as an essential element for low-power circuits. The DS injects cold electrons without a long thermal tail above the potential barrier in the channel , respectively, with a high rectifying ratio (>108).Integration of heterogeneous electronic components on a single low-power-consumption platform is highly desirable to enable applications such as the Internet of Things (IoT). Schottky diodes are important electronic components with low operation voltage and high current2 channel  metal  gate electrodes to tune the Fermi levels of 2D materials. Two-dimensional van der Waals epitaxy was performed inside an Ar-filled glovebox until the heterostructure was encapsulated by hexagonal boron nitride (hBN) to avoid any contamination through air exposure or chemicals  versus bias voltage (Vbias) curve for the DS diode at VBG = −6 V, VCG = 0 V and VTG = −0.7 V. At VBG = −6 V, graphene is p-type. When a bias voltage is applied to the graphene, electrons are injected from the p-type graphene source into the graphite drain. Note the electrons in the graphene source contributing to the current injection should have energy above the green dotted line  increases due to 2 contact and a Schottky barrier of the graphite/MoS2 contact log(10) hence values η < 1 correspond to SS below the thermionic limit. The characteristic curve at a negative gate voltage in Fig. 8).The performance of a Schottky diode is mainly characterised by two figures of merit. One is the rectifying ratio, which refers to the ratio between the on and off currents mentclass2pt{minimTo explore the switching mechanism of the DS diode, we developed an analytical formula for the ideality factor and performed numerical device simulations  does not differ significantly from the electron affinity of MoS2 (~4.2 eV)29, the Schottky barrier height at the graphene/MoS2 interface is negligible, compared to the Schottky barrier height at the graphite/MoS2 interface. This also indicates that the Dirac point of pristine graphene is located near the conduction band edge of MoS2. As shown in Supplementary Fig. 2 junction is dominated in our device. Supplementary Fig. 2 device shows an almost Ohmic IV curve, whereas graphite/MoS2 does not show an Ohmic IV curve at room temperature. Figure BG > 0, non-diode ID-Vbias characteristic curves appear.Figure D-Vbias characteristic curves, we measured the modulation of the Schottky barrier height with back-gate voltages from the activation energy in the reverse bias regime. The Schottky diode equation  versus 1/kBT in the reverse bias saturation regime (Vbias = +1 V). We extract ΦB for a given VBG from the slope of each curve. Supplementary Fig. BG regime, the device shows an almost linear ID-Vbias curve, exhibiting nearly Ohmic contact behaviour .To clarify the origin of the gate-dependent modulation of the Ition Eq.  can be rD versus control-gate voltage (VCG) transfer curve under the working conditions of the DS-FET, i.e. VBG < 0 V, where the graphene is p-type. When we apply VBG = −3 V, graphene slightly p-type. When the control-gate is placed on the MoS2 channel and the graphene/MoS2 overlapped region is swept from the off-state to the on-state, the DOS of the graphene increases according to the band diagram presented in Supplementary Fig. ave_1dec and SSave_3dec exhibits 53.6 and 58.75 mV/dec, respectively, which indicates that the proposed diode acts as a DS-FET owing to the linear energy dispersion relationship of the graphene-source electrode, resulting in a super-exponential change in the DOS. Both DS-FET and DS diode have the same origin for SS < 60 mV/dec and η < 1.To prove that the proposed diode is operated via cold carrier injection from a graphene DS at negative back-gate voltages, we measured the SS to determine if it showed sub-thermionic values. Supplementary Fig. ID-Vbias characteristic curve in the steep-slope diode regime at VBG = −6 to −2 V in 2 V step with fixed top- and control- gate voltages (VTG = −0.7 V and VCG = 0 V), where the graphene is p-doped. In the measured regime, where the top of the Schottky barrier is located below the Dirac point of graphene, η of the device is less than 1 in more than four decades of current owing to the cold charge injection from the DS at a forward bias (Vbias < 0). The minimum η that we measured in one decade of current is 0.78. The red dotted line in Fig. 8 at VBG = −6 V (>106 when VBG = −2 V and >107 when VBG = −4 V). We note that the device leakage current level is limited by the leakage currents (~10 fA) from the measurement equipment. Therefore, the reverse bias leakage current level from the diode should be lower than the measured values.Figure 2. As the linear DOS of the injected charges from p-type graphene over the top of the Schottky barrier between graphite and n-type monolayer MoS2 increases linearly from reverse to forward bias, an ideal factor below 1 is obtained in the diode with a graphene electrode as the injection source. Using gate modulation of the Schottky barrier height of the graphite/MoS2 junction, gradual switching between the diode and non-diode behaviours was also observed. The fabricated DS diode presents a minimum η as low as 0.78 in one decade of current, and it remains less than 1 for more than four decades of current at room temperature (ηave_4dec < 1), with a high rectifying ratio exceeding 108. Additionally, the device shows SS < 60 mV/dec for the same origin as that for η < 1. By using CVD-grown MoS2, graphene and graphite, integrated circuits using steep-slope DS-FETs and DS diodes can be fabricated in a large scale and pave the way for energy-efficient circuit technology.In conclusion, we successfully demonstrated the DS diode that operates based on cold charge injection from a graphene source owing to the linear DOS and a Schottky barrier at the interface between graphite and monolayer MoS2 flakes are mechanically exfoliated on a Si/SiO2 wafer. In this study, the MoS2 exfoliation was performed in an Ar-filled glovebox to prevent contamination. Using the standard dry-transfer method, each flake is picked up in the order—top hexagonal boron nitride (hBN), graphite, graphene, MoS2, and bottom hBN. After fabrication of the PC film and confirming sufficient adherence of the prepared flakes, the wafer was slowly heated to 90 °C, during which time, the sliding glass is slowly raised. During the pick-up process, owing to the large area of the top hBN, graphene, graphite, and MoS2 do not directly touch the PC film. After fabrication of the heterostructure on the PC film, the latter is slowly placed onto a prepared 285-nm-thick Si/SiO2 wafer. Subsequently, the wafer is heated to 180 °C, thereby melting the PC film. Thereafter, the PC film is successively washed using chloroform, acetone, and isopropyl alcohol (IPA). After transfer of the heterojunction to a new wafer, the device is exposed to chemicals to erase the released PC film. However, graphene, graphite, and MoS2 layers are encapsulated within large areas of the top and bottom hBN layers, which the chemicals cannot percolate. After fabricating the heterostructure on a 285-nm Si/SiO2 wafer, the standard e-beam lithography and plasma etching procedures are performed via e-beam deposition (Cr/Au = 5/60 nm) to place electrical contacts in the graphene and graphite layers. One-dimensional edge contact on graphene was formed in this process31. The hBN and graphite layers are etched using CF4/O2 and Ar/O2, respectively. Additional e-beam lithography and deposition processes are performed to facilitate top- and control-gate placement.Supplementary Fig. BG) and two Yokogawa 7651 were used to apply gate voltages to the top- and control-gate electrodes . Measurements were performed in a vacuum probe station with tri-axial cables to reduce leakage current from the measurement setup.Supplementary Fig. supplementary informationPeer Review File


The most intense response observedfor tetrahydrofuran prompted the decomposition of the DC characteristic,revealing the photoconductive and photogating effect occurring inthe graphene channel with the dominance of the latter. Our observationsshed light on understanding surface processes at the interface betweengraphene and volatile organic compounds for graphene-based sensorsin ambient conditions that yield enhanced sensitivity and selectivity.The gas sensing properties of graphene back-gated field-effecttransistor (GFET) sensors toward acetonitrile, tetrahydrofuran, andchloroform vapors were investigated with the focus on unfolding possiblegas detection mechanisms. The FET configuration of the sensor deviceenabled gate voltage tuning for enhanced measurements of changes inDC electrical characteristics. Electrical measurements were combinedwith a fluctuation-enhanced sensing methodology and intermittent UVirradiation. Distinctly different features in 1/ Moreover, defective graphenemonolayers exhibit more binding sites for target gas molecules, sosimplified fabrication methods can be even more favorable for obtainingnonideal layers for highly sensitive devices.6Two-dimensional (2D) materials, notablygraphene, have gained muchattention due to their unique physical properties, special surfaceproperties, high surface-to-volume ratio, unique charge transfer properties,and sensitivity to ambiance such as environmental conditions or electromagneticirradiation.e.g., electrical conductance. Thus, graphene devices may be used assensors based on a resistor or field-effect transistor (FET) configuration.Additional gate voltage modulation of the graphene in the FET configurationmay enhance the sensitivity when DC responses are more pronouncedin the specific gate voltage ranges.7 Severalstrategies for accelerating surface processes on graphene and relatedmaterials have been reported. Faster response and recovery times andmore pronounced changes in sensor response have been obtained by employingelevated temperatures, dopants, cocatalysts, or irradiation in theultraviolet (UV) spectral range.10 The energy provided by heat orUV LED irradiation can trigger the adsorption of molecules from thegas phase or desorption of previously attached species during therecovery time. UV irradiation at specific wavelengths may result inpartial surface cleaning or generating weakly bonded oxygen ions,preparing the active surface for further gas detection.7 However, the complexity of the physicochemicalprocesses behind the interactions at the interface when several externalparameters are employed requires further investigation before usinggraphene-based materials as reliable sensors.The nature of graphene makes its surface extremely active sinceall of the carbon atoms in the monolayer are exposed to the surroundingatmosphere. Molecular adsorption events caused by volatile compoundslead to local changes in the electrical properties, f noise (flicker noise) dominates.14 Gas molecules adsorbed on thesurface of graphene or other low-dimensional materials create scatteringand trapping centers. This leads to fluctuations in the number ofcharge carriers and their mobility.17 If a specific moleculecreates just one type of center, it is characterized by a single characteristictime constant and Lorentzian shape of the noise spectrum. In thiscase, exposure to different gases results in different characteristicfrequencies of the Lorentzian type of spectra. This gives rise tothe higher selectivity of graphene sensors.18 Overall, along with DC electrical measurements, the FES method mayenhance graphene-based sensor performance and provide additional informationabout the detected gases.Unfortunately,employing only DC resistance measurements resultsin the low selectivity of pure graphene sensors because similar responsescan be observed for different gases. One of the ways to achieve higherselectivity is to employ low-frequency noise measurements. Fluctuation-enhancedsensing (FES) utilizes information about the power spectral densityof resistance fluctuations at low frequencies where 1/20 little research has been conducted to show the influence of sensorsurface fabrication methods, pre-processing at high temperatures,and UV irradiation. It is known that the fabrication process determinesthe types of imperfections on the graphene surface, e.g., oxygen and carboxylic groups, which may be crucial for the adsorptionand desorption of molecules. Therefore, the observed resistance fluctuationsunder environmental exposure could be related to the way of graphenefabrication. An imperfect yet well-characterized graphene layer can– apart from being more sensitive and selective – simplifysample preparation requirements and reduce fabrication costs. Thereforean important question is how technological graphene preparation affectsthe sensor response.While results on detection of volatileorganic compounds (VOCs)by small-area graphene monolayers have shown the potential to distinguishbetween various organic gases with graphene-FET devices,Herein, we present studies of graphene-basedFET (GFET) sensorsfor the detection of selected VOCs, focusing on explaining possibledetection mechanisms. We combine DC resistance measurements (sensorresistance between the drain and source as a function of gate voltage)and flicker noise measurements collected at room temperature (RT)in the presence of selected gases for UV irradiated and nonirradiatedsensors. We study GFET responses toward selected volatile organicgases after cleaning graphene at high temperatures and in a vacuum.We show that the cleaning procedure allows graphene sensor preparationthat yields more sensitive gas detection by reducing the influenceof humidity and pollutant molecules adsorbed on the surface from laboratoryair. Finally, we present the results of graphene aging and the possibilityof refreshing the sensors by employing UV irradiation and inert gaspurging.e.g., chemical composition,electronic configuration, molar mass, and polarity – see Table S1 for comparison). Therefore, differencesin their adsorption mechanisms on graphene are expected, resultingin different resistance and spectral noise changes. Moreover, additionalUV enhancement effects can be observed for graphene yielding highlydifferent sensor responses compared to dark conditions.DC resistance vs gatevoltage and fluctuation-enhanced sensing were employed to study thegas-induced response of the GFETs to tetrahydrofuran, acetonitrile,and chloroform, as schematically shown in www.graphenea.com) and transferredit from copper to SiO2/Si substrate using the proceduredescribed in detail elsewhere.2123 The observed morphological defects may bedue to partial overlapping of graphene monolayers as well as cracksexposing their edges. The defective morphology results from graphenegrowth on Cu foil during the CVD process and further mechanical processingof graphene layer transfer on the SiO2/Si substrate. Fordetection, such defects create potential binding sites for ambientgas molecules.We used graphene grown by the chemical vapor deposition(CVD) methodon the surface of thin copper foils (–7 mbar) accordingto the description provided in Methods. The initial cleaning resultedin the increase of sensor resistance, RS, with a more pronounced change at higher positive gate voltages,with an ∼88% increase of RS at VG = 30 V. Characteristic drain–sourcecurrent IDS vs gate voltage VG curves after GFET cleaning are depicted in Figure S1. Thermal annealing was earlier provedto increase the total graphene resistance and introduce defects servingas adsorption sites for gas sensing performance improvement.24 The RS vs VG characteristics for the different gases arepresented in Figure S2 shows the responseof the GFET sensor presented as a relative change of sensor resistancein relation to the nitrogen case as a reference in the dark and underUV light for the broader presentation of collected data. As seen,in all cases, resistance increases with the increased gate voltage,which corresponds to the p-doped graphene. Nitrogenwas used as a carrier gas in all measurements; thus, we consider thenitrogen case a reference in DC and noise studies. The solid red linein RS vs VG characteristics of a GFET under nitrogen exposure. Measurementsin acetonitrile, tetrahydrofuran, and chloroform were performed onthree consecutive days after the cleaning procedure, which was requiredby the long recovery time of the graphene layer.Before DC and noisemeasurements, the GFET sensor was cleaned at a high temperature (∼300°C) in a vacuum (∼10VG = 60 V duringconsecutive days).The sensor was kept in a desiccator under low vacuumovernightbetween subsequent days to limit its exposure to oxygen and humiditypresent in laboratory air and maintain the cleanliness of the sensorsurface. Control measurement in laboratory air conditions was conductedeach day to verify that the sensor recovers overnight , even for polar molecules.26 For small molecules, including inorganic ones, adsorption energieson graphene were calculated to be relatively low.27 For aromatic molecules, calculations suggest that π–πstacking leads to about equal magnitude of dispersion and Coulombinteractions.28 Patil et al. showed thatthe geometric configuration of organic molecules significantly influencesthe adsorption energy.29 The authors demonstratedthat molecules were physisorbed on graphene with negligible chargetransfer for chloroform but that significant charge rearrangementoccurred due to induced dipole interactions. Thus, the type of organicmolecule, including functional groups, electronic configuration, polarity, etc., gives rise to different interactions between the adsorbateand graphene.The differences between thesensor response to the organic gasmolecules may be caused by the different chemical nature of the threeorganic compounds. Samnakay et al. reported that the polarity of organicvapors could explain differences in MoS29 creatinga depletion layer at the interface. Thus, hole accumulation in graphenemay reduce resistance if the sensing material acts as a p-type semiconductor,as shown in 26 the DC responses obtainedin our study are relatively low. These sensor responses can be comparedto calculated adsorption energies, which are reported to be in therange of 234 and 286 meV for acetonitrile26 and 357 meV for chloroform.30Chloroform is regarded as a nonpolar solvent becauseof its lowpolarity and small electrical permittivity, and yet it reduces theGFET sensor resistance, as observed in 32 Tetrahydrofuran (THF) is a cyclic molecule with an oxygen atom inits structure (Table S1). Calculationsshow that it forms coordinated bonds and adsorbs either without orwith ring-opening and form a bridge-like structure. The latter caseis energetically favorable if the activation energy for ring-openingcan be overcome.32 Charge transfer to thegraphene substrate via the nucleophilic O atom couldexplain the significant increase of the GFET sensor resistance in Figure S3 presents the GFET sensor recovery aftertetrahydrofuran exposure. The reversible sensor characteristic suggestsmolecular THF bonding, i.e., no ring-opening reaction,upon adsorption under UV irradiation. The effect of a strong shiftinto the n-type channel is then attributed to the dative bonding ofO in THF to graphene. This qualitative explanation requires, however,more in-depth studies. Some light is shed by the in situ FTIR spectra measurements discussed below.Tothe best of the authors′ knowledge, no detailed quantificationof adsorption of tetrahydrofuran on graphene is reported in the literature.However, the adsorption process with a ring-opening effect was reportedfor the solvent and conventional semiconductors.Figure S4a). Theseresults suggest that the electrophilic C atom in acetone dominatesthe sensor response, while for THF, the π-bonded C ring structureredistributes excess electrons, and charge transfer from the O atomin THF to graphene dominates the sensor response. Previous theoreticalwork shows that acetone adsorbs favorably with oxygen and hydrogenatoms above the hollow site of the carbon ring by weak van der Waalsinteractions and that acetone acts as an electron acceptor,34 qualitatively confirming the slightly decreased resistance seenin Figure S4a at high VG voltages.The C=Obond in acetone can provide both an electrophilicC+ atom and a nucleophilic O– atom upon adsorption and liftingof the resonant double bond to a predominantly single-bonded species.As a result, depending on the adsorbate bonding configuration, C canact as an electrophile and O can act as a nucleophilic site. In contrastto THF, our measured DC characteristic shows a slight decrease inresistance upon acetone exposure, and no shift toward positive gatevoltages was observed  and only a slight change in RS  are evident, suggesting that the dominating effect onthe DC response upon UV irradiation of the THF-exposed GFET is thephotogating effect. The same dominant photogating effect is also observedin the recovery phase .Returning to THF exposure of the GFET,a close-up in Figure S5). In situ transmission FTIR spectra reveal two absorption bands at ∼1000and ∼850 cm–1 upon THF adsorption on graphenethat can be attributed to the O–C–O stretching and out-of-planeC–H mode in THF, respectively. They are red-shifted comparedto liquid THF (blue dotted line), signaling intramolecular C–O–Cbond-weakening and charge redistribution of electrons in the ringstructure upon adsorption, corroborating the DC sensor characteristicswith electron transfer from the O atom in THF and concomitant chargeredistribution in the ring structure.FTIR measurements were performed to characterize THF adsorptionon graphene /VS2 × f. The noise spectracollected in the dark  show a characteristicfrequency maximum of the power spectrum at ∼1 Hz in the dark,like THF. However, since the DC responses are opposite for THF andacetone , we notethat discrimination between these two gases is possible with combinedDC and noise measurements, therefore enhancing the selectivity ofthe GFET sensor. Comparing our results with those reported by Balandin14 and Rumyantsev,18 we see that corner frequencies (frequencies at which a plateau occurson the 1/f noise spectrum) occur in similar rangeswith minor shifts, suggesting that the dominant factor is the activematerial itself, even though the active area in the case of our sensor(∼0.2 mm2) is at least a few thousand times largerthan in abovementioned works. At the same time, larger sensing areasusually allow more accessible fabrication routes, making the processfaster and cheaper.Noise measurementswere conducted to complement DC response studies. the dark 4a revealthe dark 4b. This RS vs VG characteristics and low-frequencynoise spectra. VG = 60 V for seven consecutive days of chloroform gas exposure withoutadditional sensor cleaning. Day 0 refers to a fresh, cleaned sensorthat is highly responsive to chloroform, especially under UV light(baseline in nitrogen reached ∼10 kΩ on day 0). The sensorresponse does not recover to its pristine state during subsequentdays. The baseline resistance at VG =60 V in nitrogen ranged between 5 and 6 kΩ for subsequent days.Much lower changes in RS in the presenceof chloroform under UV light are observed, whereas the sensor responseremains almost intact in the presence of chloroform without UV irradiation.On the other hand, noise spectra collected during seven days werecharacterized by reproducible shapes with minor changes in noise level,as depicted in –8 when the sensor was exposed to both chloroform andUV irradiation. No strict dependence between the number of days andnormalized power spectral density was observed. Thus, in contrastto DC measurements, the noise spectra exhibit a more repeatable sensorresponse for the back-gated GFET.Next, we studiedthe GFET aging process by measuring 2, which we refer toas a refreshing process. We employed UV irradiation with N2 purging after the repeated chloroform exposure measurements depictedin RS changes after a total of 100 min of refreshing.As expected, the fastest changes appear in the first 20 min. The curvesafter 90 and 100 min overlap each other, indicating that after sucha long time, RS stabilizes and attainsa value close to that of a cleaned surface. UV irradiation removespreviously adsorbed species (including oxygen or chloroform residues),and the inert atmosphere prevents readsorption of additional oxygenand humidity. Nevertheless, the cleaning effect with only UV lightis not as efficient as heating under high-vacuum conditions. 2 and UV irradiation do not affect noise spectra, which supportsour assumption that organic gases cause the characteristic featuresvisible in the noise spectra in Finally, we investigated the GFET sensor responseafter UV lightexposure in an inert atmosphere of Nf noise measurements. The results presented in this workinclude GFET sensor performance in various ambient conditions, showinghow selected technological  or aging processes influence the sensing performance.It is shown that the large effective sensing area of the investigatedGFET of about 0.2 mm2 allowed analysis of characteristicfeatures in the normalized noise spectra, which were different forall vapors and appeared in similar ranges as reported previously forgraphene sensors employing thousand times smaller sensing areas. Foracetonitrile and chloroform, the changes in the DC characteristicscould be explained by the difference in their theoretical adsorptionenergies and their polarity. In the case of chloroform, the decreasein sensor resistance may be ascribed to its molecules binding favorablywith negatively charged chlorine, creating a hole accumulation layerin p-doped graphene. Tetrahydrofuran significantlyaffected the sensor DC characteristic, shifting the RS vs VG curve by ΔVG = 15.35 V and ΔRS = 128.8 Ω. A dominant photogating effect suggests thata considerable number of charge carriers occur near the channel structureduring the detection process. This creates a potential that acts asan additional gate voltage and shifts the characteristic curve towardnegative VG values. It is inferred thatTHF adsorbs nondissociatively . A charge transfer reaction fromthe O atom in THF to graphene dominates the sensor response, leadingto an increase in the resistance. Our studies also revealed that sensoraging mainly affects DC responses and not the noise spectra. We alsoconfirm that annealing at high temperatures under low vacuum cleansthe graphene surface more effectively than refreshing with only UVirradiation (275 nm) under a constant nitrogen flow.In this work, we studied CVD graphene back-gatedFET sensor responsestoward acetonitrile, tetrahydrofuran, chloroform, and acetone gasesemploying resistance vs gate voltage characteristics and 1/The studyshows that measurements of the GFET transfer characteristicscombined with the FES method enhance the sensor sensitivity and selectivity.UV-assisted graphene-based sensors with reproducible features andlow fabrication costs have the potential to develop a new group ofhighly sensitive, selective, and reversible gas sensors. By utilizinga well-defined combination of DC and noise studies, we propose a newdirection in miniaturized gas detection systems by 2D materials. Webelieve there is still wide room for development in this area, butthis path is undoubtedly worth noting and following in future scientificconquests.2. Afterward, an electrochemical delamination techniquewas employed to transfer PMMA-coated CVD graphene from copper foil(from Graphenea) onto the SiO2/Si substrate. This techniqueallows for the deposition of graphene on large areas. After the transferprocess, the wafer was subsequently heated at 130 °C for 24 hand then rinsed in acetone to remove the PMMA layer. The graphenelayer was patterned by laser lithography and etched by reactive-ionetching in oxygen plasma. Finally, source and drain contacts werepatterned by laser lithography and fabricated by Ti/Au (5/150 nm thick)evaporation. Prior to back-gate contact deposition, SiO2 was removed from the backside of the Si wafer with HF. The backsideof the wafer was metalized with Cr to serve as the back-gate of graphene-basedfield-effect transistors (GFETs). See Figure S6 for the schematic of the step-by-step GFET fabrication procedure.The channel length and width of the studied GFET were L = 635 μm and W = 320 μm, respectively.Optical characterization of the fabricated GFET was performed witha laser confocal microscope . Insitu transmission FTIR spectra of graphene samples undergas and UV light exposure and liquid solvent as a reference were recordedwith a Bruker 80v spectrometer.Alow-resistivity silicon wafer was first cleaned and then put intoa furnace chamber for ∼30 min at 1000 °C for thermal growthof SiORS) vs gate voltage (VG) characteristics were collected in the VG range between −60 V and +60 V at selected operating conditionswith 2 s hold time and the drain–source voltage bias set to1 V. In the FES measurements, the sensor was connected in a circuitconsisting of a low-noise operational amplifier and biased by a currentsource set to ∼90 μA (yielding a voltage across the sensorof ∼0.2 V). The gate voltage VG was set to 0 V in the FES measurements. Such input parameters enabledmeasuring the 1/f noise originating from the materialwithout interference from inherent noise from the measurement system. Figure S7 shows that the normalized power spectraldensity is nearly constant at the selected operating conditions, regardlessof the input current. The power spectral density of voltage fluctuationscaused by the input current flow was measured using a data acquisitionboard  and a home-scriptedLabVIEW program. During all measurements, the sensor was kept insidea metal shielding box to avoid external electromagnetic interference.For experiments with UV irradiation, a UV LED with maximum opticalpower at the wavelength of 275 nm was used and positioned approximately 1 cm from the sensor surface, yieldingan optical power density in the range between 1.06 and 1.59 mW cm–2.A custom-preparedprobe station with titanium needles was used to connect GFET electrodeswith the measurement and bias units. A parameter analyzer  with two source-measure units was used for recording DC characteristics. Sensor resistance (–1) and annealing the sensor at ∼300 °C for 30 min in avacuum between about 1 × 10–7 and 5 ×10–7 mbar. After the heating process, the sensorwas left in the vacuum chamber until cooling down to room temperatureand transferred to the sensing chamber. In the gas sensor measurements,gas was admitted to the sample through a metal pipe connected to thegas distribution system, with the end pipe placed within 0.5 cm fromthe sample. Organic vapors were produced by feeding 50 mL/min of nitrogen(N2) gas through a glass beaker containing the selectedorganic liquid. Three organic solvents were used: acetonitrile, tetrahydrofuran,and chloroform. Additionally, acetone was used for supplementary studies.The constant overall gas flow was regulated by a mass flow controller; therefore, the concentration of producedvapors admitted to the sample depended only on the N2 flowrate and vapor pressure of the organic liquid. The estimated concentrationsvaried for gases used in our experiments as follows: acetonitrile∼156 ppm, tetrahydrofuran ∼100 ppm, chloroform ∼100ppm, and acetone ∼110 ppm. For each cycle of measurements,the sensor was subjected to the selected gas for 20 min in dark conditionsand then another 20 min with additional UV irradiation to obtain asteady state. All measurements were conducted at room temperature(RT ∼23 °C) and ambient pressure (∼1 bar).Annealing at high-vacuum conditionswas employed to prepare GFET sensors for gas detection. The procedureincluded slow heating (at a rate of ∼2 °C min