High-efficiency and low dark current crystalline selenium-based heterojunction photodiode with a high-quality tellurium nucleation layer
In this study, a high-efficiency and low dark current thin-film crystalline selenium (c-Se)/gallium oxide (Ga2O3) heterojunction photodiode is demonstrated via improving the deposition conditions for the tellurium nucleation layer that prevents the peeling of the selenium film during annealing. The highly (100)-oriented polycrystalline selenium film is grown by employing a thin tellurium (Te) nucleation layer with high-quality crystallinity. The device exhibits high external quantum efficiency in the visible region and extremely low dark current that is below 100 pA/cm2 at a reverse-bias voltage of 15 V at room temperature. The result indicates the high potential of crystalline selenium-based photodiodes to be used as photoconversion layers in imaging devices.
Low-Dark-Current Photodiodes Comprising Highly (100)-Oriented Hexagonal Selenium With Crystallinity-Enhanced Tellurium Nucleation Layers
The fabrication of low-dark-current heterojunction photodiodes based on p-type highly (100)-oriented crystalline selenium (c-Se)/n-type gallium oxide (Ga<sub>2</sub>O<sub>3</sub>) was demonstrated by enhancing the crystallinity of the tellurium (Te) nucleation layer. The preferential (100) crystal orientation of c-Se is significantly improved by using high-quality Te nucleation layers that are thermally evaporated at a relatively high Te-source temperature (<inline-formula> <tex-math notation="LaTeX">$\text{T}_{Te}$ </tex-math></inline-formula>) without substrate heating. The fabricated device exhibits an extremely low-dark current under 100 pA/cm<sup>2</sup> (at room temperature) and a high external quantum efficiency of over 85% at a wavelength of 550 nm at a reverse bias of 15 V. These results demonstrate the potential of c-Se-based photodiodes to provide highly sensitive imaging devices.
Testing digital circuits using a Mixed-Signal Automatic Test Equipment
This paper presents the results of parametric testing of digital ICs using a dedicated Mixed Signal Automatic Testing Equipment. Due to the prohibitive price of the ATE equipment and dedicated Device Interface Board (DIB) for digital Integrated Circuits (ICs), a DIB for analog circuits was used to perform the testing. Despite the challenges presented by the experiments, the results prove to be accurate for the performed tests, according to the data sheet of the digital ICs and production test data provided by the manufacturer.