Analysis of Drain-Induced Barrier Lowering in InGaZnO Thin-Film Transistors

Characterization of short-channel amorphous indium gallium zinc oxide (InGaZnO) (a-IGZO) thin-film transistors (TFTs) has been a crucial issue to realize higher resolution display and heterogeneous integration with complementary metal-oxide-semiconductor (CMOS) technology. In this work, the drain-induced barrier lowering (DIBL) of the a-IGZO TFT was investigated with the variations in oxygen content in the IGZO layer. In order to accurately investigate the effect of the drain voltage on the channel potential, it is necessary to analyze the energy band diagram based on the dopant profile of the channel region. A new method for extracting the channel dopant profile through a simple C-V measurement of the a-TFT sample was proposed. We performed TCAD device simulation based on the extracted density of states and dopant profile of IGZO layer and confirm good agreement with the measured I-V characteristics of a-IGZO TFTs with various oxygen contents. The effective channel length was found to be short with decreasing the oxygen content in the IGZO channel layer. The DIBL effect becomes more severe as the oxygen content decreases. Our methodology, which was successfully verified in this work, can be utilized for the analysis of short-channel effects including DIBL for the scaled a-IGZO TFTs.