Schottky Barrier Modulation in Surface Nanoroughened Silicon Nanomembranes for High-Performance Optoelectronics

Surface nanostructures of silicon nanomembranes (SiNMs) play a dominant role in modulating their energy band structures and trapping surface charges, thus strongly affecting the Schottky barrier height, the surface resistance, and the optoelectronic response of Schottky-contacted SiNMs. Here, controllable nanoroughening of SiNMs without substantial changes in thickness was realized via a metal-masked chemical-etching approach. The mechanism of surface roughness effect on the electrical characteristics and contact properties of SiNM-based diodes and thin-film transistors was investigated. Meanwhile, photodetective devices were fabricated by utilizing rough SiNMs, and significant dark current suppressions were demonstrated due to surface depletion and Schottky barrier modulations. Moreover, by introducing a three-terminal device structure (adding a gate), the photoresponse could be further enhanced with high current on/off ratio. Our work may provide guidance for creating and designing principles of SiNM-based optoelectronic devices, especially for Schottky barrier modulations.