Discharge Current Analysis Estimating the Defect Sites in Amorphous Hafnia Thin-Film Transistor

Abstract

Defects in amorphous oxide thin-film transistor (TFT) influence major transistor parameters such as the threshold voltage, mobility, and subthreshold slope. Thus, understanding these defects is crucial in securing high-reliability and high-performance devices. However, only very limited electrical analysis methods such as multi-frequency C-V and temperature-dependent I-V methods have been applied to accumulation mode devices and these do not provide direct pictures of the defects during carrier transport. In this investigation, we employed the discharging current analysis method to attain quantitative information involving the defect densities of amorphous hafnium-indium-zinc-oxide (a-HIZO) TFT. We were able to estimate the number of defect sites of a-HIZO TFT as being of the order of 1018/cm(3), although this is dependent on the Hf content. We believe that this method can be widely used to estimate the defect density of oxide TFTs.