Physically-based simulation of zinc oxide thin-film transistors: Contact resistance contribution on density of states

Abstract

In this work, using a physically-based simulator, the density of states DOS is modeled to reproduce the experimental electrical characteristics of ZnO TFTs fabricated by Ultrasonic Spray Pyrolysis at 200°C. The contact resistance was experimentally extracted from the ZnO TFTs and included into the simulation, in order to separate the metal–semiconductor interface contribution from the DOS. A comparison between the modeled DOS considering the contact resistance and disregarding it is also presented. It is proposed to consider the acceptor-like states and the tail-donor states, where the deep-acceptor states have approximately an exponential form and the distribution of tail-acceptor states are sharper than the distribution of tail-donor states. The simulated electrical characteristics reproduce very well the experimental data at different channel lengths. The use of physically-based simulation can be useful to model the DOS of Oxide semiconductor films in TFTs by reproducing the experimental data.