Field-induced macroscopic barrier model for persistent photoconductivity in nanocrystalline oxide thin-film transistors

Persistent photoconductivity (PPC) in nanocrystalline InZnO thin-film transistors (TFTs) was studied using carrier fluctuation measurements and transient analysis. Low-frequency noise measurements and decay kinetics indicate that the band bending by the external field together with the ionized oxygen vacancy (V-o(++)) generated during the light exposure is the main cause of the PPC phenomenon. Based on these observations, a field-induced macroscopic barrier model is proposed as the origin of PPC for InZnO TFTs. In particular, this model explains that the carrier separation between e and V-o(++) is induced by the external field applied to the three electrodes inside the transistor. (C) 2014 AIP Publishing LLC.