A simple-structured silicon photodetector possessing asymmetric Schottky junction for NIR imaging

Abstract

In this work, we design a minimalist Au/Si/Ag photodetector (PD) with asymmetric Schottky junctions (ASJ) combined with asymmetric geometrical contacts (AGC). Compared with the AGC-only PD (Ag/Si/Ag), the Au/Si/Ag PD possesses an efficient photodetection in visible to near-infrared (NIR) region. The experimental results show that the Au/Si/Ag PD exhibits a high responsivity of 424.3 mA/W, a low dark current of 8.5 pA, a high detectivity of 3.35×1013 Jones, and a wide linear dynamic range (LDR) of 187 dB, at the wavelength of 980 nm with 0 V bias voltage. That means this PD has a competitive performance compared to the reported Si-based PDs. Using this high-performance PD, we successfully demonstrate an NIR transmission imaging application, proving its NIR imaging capability. More importantly, the Au/Si/Ag PD has the advantage of facile preparation, i.e. neither expensive new materials nor complex processes are needed, providing a new route for the construction of low-cost self-powered PDs as NIR imaging sensors.