Transport mechanism in sub 100°C processed high mobility polycrystalline ZnO transparent thin film transistors

Abstract

We demonstrate high performance ZnO TFTs with record field effect mobility 229 cm2/V.s, on/off ratio exceeding 107 (limited only by our simple device structure) and sub threshold swing (S) <;150 mV/dec, surpassing the performance of many reported amorphous Indium Gallium Zinc Oxide (a-IGZO) thin film transistors.1,2 The tail state distribution of the density of states (DOS) in ZnO extracted via 2D numerical simulations matched to experiment, demonstrates unequivocally a similar mobility mechanism that underpins all Transparent Conducting Oxides (TCOs)-whether amorphous or not. The characteristic Temperature of ZnO is found to be ~463 K and the tail state density of states (DOS) is ~1.3 ×1020cm-3eV-1.