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Density of States-Based Design of Metal Oxide Thin-Film Transistors for High Mobility and Superior Photostability

2012; American Chemical Society; Volume: 4; Issue: 10 Linguagem: Inglês

10.1021/am301342x

1944-8252

Hyun‐Suk Kim, Joon Seok Park, Hyun-Kwang Jeong, Kyoung Seok Son, Tae Sang Kim, Jong‐Baek Seon, Eunha Lee, Jae Gwan Chung, Dae Hwan Kim, Myungkwan Ryu, Sangyoon Lee,

CCD and CMOS Imaging Sensors

A novel method to design metal oxide thin-film transistor (TFT) devices with high performance and high photostability for next-generation flat-panel displays is reported. Here, we developed bilayer metal oxide TFTs, where the front channel consists of indium-zinc-oxide (IZO) and the back channel material on top of it is hafnium-indium-zinc-oxide (HIZO). Density-of-states (DOS)-based modeling and device simulation were performed in order to determine the optimum thickness ratio within the IZO/HIZO stack that results in the best balance between device performance and stability. As a result, respective values of 5 and 40 nm for the IZO and HIZO layers were determined. The TFT devices that were fabricated accordingly exhibited mobility values up to 48 cm2/(V s), which is much elevated compared to pure HIZO TFTs (∼13 cm2/(V s)) but comparable to pure IZO TFTs (∼59 cm2/(V s)). Also, the stability of the bilayer device (−1.18 V) was significantly enhanced compared to the pure IZO device (−9.08 V). Our methodology based on the subgap DOS model and simulation provides an effective way to enhance the device stability while retaining a relatively high mobility, which makes the corresponding devices suitable for ultradefinition, large-area, and high-frame-rate display applications.