Application of Microwave Photoconductivity Decay Method to Characterization of Amorphous In-Ga-Zn-O Films

Microwave photoconductivity decay (μ-PCD) method was applied to evaluate the effects of chemical composition and Ar plasma induced damage on the bulk and the surface states in amorphous In-Ga-ZnO (a-IGZO) films. It was found that the peak reflectivity signal in the photoconductivity response increased with decreasing the Ga content, and had a strong correlation with the a-IGZO transistor performances. In addition, the peak reflectivity signals obtained after various Ar plasma treatment duration were well correlated with the transistor characteristics. With Ar plasma treatment, the peak reflectivity signal decreased in accordance with degradation of transistor characteristics. The μ-PCD method was found to be a very useful tool not only to evaluate the bulk and the surface states, but also to predict the performance of a-IGZO transistors subjected to various plasma processes in the production. key words: microwave photoconductivity decay, a-IGZO, oxide semiconductor, photoconductivity response