EFFECT OF GRAIN BOUNDARY ON THE CHARACTERISTICS OF POLY-SiMETAL–INSULATOR–SEMICONDUCTOR PHOTODETECTOR

Abstract

The effect of grain boundary on the characteristics of poly- Si metal–insulator–semiconductor photodetector is investigated utilizing two-dimensional device simulator. In the investigation, the trap states in grain boundary are composed of two types: tail states and deep-level states, both of which consist of acceptor-like trap and donor-like trap. The simulation results show that the photocurrent of photodetector decreases considerably in the case of tail states above 5 ×19 cm-3, but less susceptible to deep-level states. Furthermore, it is found that the spectral responsivities of the photodetector decrease when the energy level of acceptor-like traps shifts towards the midgap, but keep unchanged for the case of donor-like traps.