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

•DOS is modeled to reproduce the experimental electrical characteristics of ZnO TFTs.•Contact resistance was extracted from the ZnO TFTs and included into the simulation.•Higher density of acceptor-like states is necessary to compensate the Rc contribution.•Rc and acceptor-like states may affect the electrical characteristics in similar ways.

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.