Subgap Density-of-States-Based Amorphous Oxide Thin Film Transistor Simulator (DeAOTS)

The amorphous oxide thin-film transistor (TFT)-oriented simulator [subgap Density of states (DOS)-based Amorphous Oxide TFT Simulator (DeAOTS)] is proposed, implemented, and demonstrated for amorphous indium-gallium-zinc-oxide (a-IGZO) TFTs. It only consists of parameters having their physical meanings and is supplied with concrete techniques for parameter extraction. Among the physical parameters, the acceptor-like DOSgA(E) was experimentally extracted using the multifrequencyC-Vtechnique, whereas the donor-like DOSgD(E) and the doping concentrationNDwere extracted using numerical iterations. The simulation result reproduces the DOS and thin-film-thickness-dependence of dcI-Vcharacteristics very well. Compared with the previously reported a-Si TFT models, the proposed DeAOTS model not only reflects the strongVGSdependence of the effective mobility (μeff) but also clarifies the relations between process-controlled DOS parameters and dcI-Vcharacteristics based on experimentally extracted DOS parameters. Also, it sufficiently takes into account the peculiar situation of amorphous oxide TFTs where the free-carrier charge can be larger than the localized one out of the total induced charge. Moreover, it reproduces the measured electrical characteristics within the wide range ofVGS/VDSwith a single equation, not distinguishing the operation regions such as the subthreshold, linear, and saturation regimes.