Electronic transport parameters of indium zinc oxide thin films after Al2O3/HfO2 top-dielectric formation annealing

Abstract

Oxide-based dielectrics can be formed on indium zinc oxide (IZO) through oxidation of deposited metallic layer such as Al and Ti. The metal/IZO reactions necessary for dielectric oxidization tend to consume oxygen from the IZO channel and thus lead to the formation of oxygen-deficiency defects in the IZO layer. However, if the formation of such defects is significant at room temperature, it may adversely impact the long-term reliability of IZO devices. This work presents results of a study of electronic transport in IZO insulator/semiconductor structures measured immediately after the oxidizing anneal and 1 year thereafter. The sample measured 1 year after annealing exhibited a nearly one order of magnitude increase in electron concentration, indicating that donor-like defects are formed under ambient room temperature conditions. Furthermore, and in contrast to the isotropic nature of electron transport in the sample measured immediately after annealing, significant anisotropy in transport parameters was found in the sample measured 1 year after annealing.