Enhanced performance of self-powered Ge Schottky photodetectors enabled by 2D hBN monolayer passivation

Abstract

Ensuring high-quality surface passivation is the key to realizing high-performance self-powered optoelectronic devices, as it significantly impacts carrier transport. 2D hexagonal boron nitride (hBN) exhibits exceptional material characteristics, including a wide bandgap, high dielectric constant, minimized dangling bonds, and high chemical stability, making it one of the most promising candidates for high-quality passivation. Nevertheless, the passivation characteristics of hBN on Ge and their influence on self-powered photodetection remain unexplored, as well as their effects on carrier recombination lifetime, interface defect density, and Schottky barrier height. In this study, the first demonstration of enhanced Schottky junction photodiode characteristics and the impact of the surface passivation on carrier lifetime and defect density using an hBN monolayer on Ge are presented. The characteristics of hBN/Ge with Al2O3/Ge are compared to demonstrate the superior passivation quality of hBN over conventional materials. These results highlight the significant potential of hBN as an effective passivation for optoelectronic device applications.