Interfacial Contact Engineering Enables Giant-Performance Semiconductor Nanomembrane Optoelectronic Devices

Abstract

Contact properties at a nanoscale interface critically influence the electrical behaviors of heterogeneous semiconductor devices. Herein, a platform is established to systematically investigate semiconductor nanomembrane interfacial contacts and their impact on the optoelectronic performance of various heterojunctions. Photodiodes with asymmetrical and symmetrical junctions are synthesized through a combination of different contact material stacks and processing steps. Adjusting the surface Schottky barrier height is essential in controlling charge injection and reducing the noise current. Two principal strategies are utilized to enhance the Schottky barrier: surface passivation through interfacial reactions and tuning the buffer layer work function. For electron-rich Si nanomembranes (SiNMs), an indium-tin-oxide (ITO) buffer layer is demonstrated to boost the Schottky barrier through both above strategies by varying device fabrication processing. The work-function tunable semiconductor-like ITO (semi-ITO) is developed for the Schottky junction, while the Ohmic contact is optimized by inserting an emerging low work-function ytterbium oxide (YbO_x) layer. Extraordinary performance in sensing faint light is demonstrated, including fA/ µm level reverse dark current, rectification ratio of ≈10⁸, picowatt-level illumination resolution, self-powered detection, and rapid response speed (≈2.57 µs rise time). This research offers a universal approach to modifying interfacial contacts for advanced semiconductor nanomembrane optoelectronic devices.