Performance Improvement of In-Ga-Zn Oxide Thin-Film Transistors by Excimer Laser Annealing

TL;DR

Excimer laser annealing improves the performance of oxide thin-film transistors by enhancing their electrical and optical stability.

Contribution

A dual-heterojunction TFT structure with excimer laser annealing achieves high mobility and stable operation.

Findings

Field-effect mobility improved to 9.8 cm²/V·s using excimer laser annealing.

The device demonstrated good optical stability despite performance enhancements.

Electron accumulation at interfaces confirmed the conduction mechanism in the a-IGZO channel.

Abstract

We applied excimer laser annealing (ELA) on indium-zinc oxide (IZO) and IZO/indium-gallium-zinc oxide (IGZO) heterojunction thin-film transistors (TFTs) to improve their electrical characteristics. The IZO and IZO/IGZO heterojunction thin films were prepared by the physical vapor deposition method without any other annealing process. The crystalline state and composition of the as-deposited film and the excimer-laser-annealed films were analyzed by X-ray diffraction and X-ray photoelectron spectroscopy. In order to further enhance the electrical performance of TFT, we constructed a dual-heterojunction TFT structure. The results showed that the field-effect mobility could be improved to 9.8 cm2/V·s. Surprisingly, the device also possessed good optical stability. The electron accumulation at the a-IZO/HfO, HfO/a-IGZO, and a-IGZO/gate insulator (GI) interfaces confirmed the a-IGZO-channel conduction. The dual-heterojunction TFT with IZO/HfO/a-IGZO-assisted ELA provides a guideline for overcoming the trade-off between high mobility (μ) and positive VTh control for stable enhancement mode operation with increased ID.

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