Modeling and Simulation of Hydrogenated Amorphous Silicon Thin-Film Transistors

Abstract

A simple analytical dc model for hydrogenated amorphous silicon thin-film transistors including an accumulation region is developed. The model describes the device properties and physical phenomena of hydrogenated amorphous silicon. Current–voltage characteristics are related to basic material and device parameters. In the blocking state, drain leakage current is modeled using previously reported results. In the lower and upper threshold regimes, both deep and tail states are taken into account. The density of states in band gap is modeled by assuming an exponential distribution of the deep and tail states. The results show that the generated current–voltage characteristics show good agreement with previously reported data. The study of apparent threshold voltage, field effect mobility and ON–OFF current ratio shows that in the lower threshold regime, parameter behavior is governed by the deep states in the middle of an amorphous silicon gap while the tail state distribution controls the upper-threshold-regime behavior. The model is simplified analytically to lessen the cost of and complexity in fabricating large-area displays and optimizing their performance.