Direct synthesis of two dimensional MoS2 on p type Si and application to solar hydrogen production
AbstractTransition metal dichalcogenides (TMDs) are promising two dimensional (2D) materials, and MoS2 has been specifically utilized in electronic devices and integrated circuits. However, the direct synthesis of MoS2 on traditional semiconductors, such as silicon, remains challenging due to the hydrophobic surface of nonoxide wafers (e.g. Si, GaAs, and InP) Herein, a novel, facile, reliable, and one step method for the direct synthesis of single crystal MoS2 on a p Si wafer via hybrid thermolysis is proposed. To demonstrate the applicability of the proposed method, a MoS2/p Si heterojunction was fabricated and used for solar driven hydrogen production. The as fabricated n MoS2/p Si heterojunction exhibited a benchmark current density of 13.5 1 mA/cm2 at 0 V and an onset potential of +0.02 V. This method reliably and efficiently produced high quality MoS2 crystals on a wafer scale and is sufficiently simple to overcome the challenges associated with previous approaches. The method developed herein represents a tremendous advancement in the fabrication of 2D electronic devices.2D semiconductors: Taming unruly crystals for green energySolar panels that catalyze the splitting of water into hydrogen fuel and oxygen can now be fabricated using a simple deposition process. Interfaces between two dimensional molybdenum disulfide (2D MoS2) and electron poor silicon can split water using light, but only when the naturally random crystallization patterns of 2D MoS2 are inhibited. Researchers led by Ho Won Jang from Seoul National University and Soo Young Kim at Chung Ang University, Seoul, have improved uniformity in this ultrathin material by initially coating silicon wafers with a molybdenum oxide precursor that adheres in smooth layers. By depositing a second, sulfur rich coating and then heating the sample, the team produced uniform 2D MoS2/silicon junctions down to 10 nanometer scales. The transparent device maintained a water splitting photocurrent for over forty hours without degradation, thanks to the corrosion resistant nature of high quality 2D MoS2 crystals.A direct synthesis method for high quality MoS2 thin films on p Si wafer is reported herein. To increase the hydrophilicity of the p Si wafer, MoO3 was deposited before spin coating. The (NH4)2MoS4 precursor was easily coated onto the MoO3/p Si and was converted to a MoS2/p Si heterojunction via thermolysis. This method has the potential to be used in 2D electronic device fabrication in the future.
NPG Asia Materials