Improved High-Performance Solution Processed In₂O₃ Thin Film Transistor Fabricated by Femtosecond Laser Pre-Annealing Process

Fei Shan,Seungmoon Pyo,Jae-Yun Lee,Sung-Jin Kim,Hao-Zhou Sun

doi:10.1109/access.2021.3056774

Abstract

The low-temperature annealing process has a critical impact on the electrical performance of thin-film transistors (TFTs). This paper reports significant performance enhancements of TFTs using a femtosecond laser pre-annealing (FLA)-based preparation method. The solution-processed In 2 O 3 films were fabricated by FLA at various laser irradiation times and then annealed on a hot-plate at 230 °C. When the FLA time was set to 30 s, the device exhibited high saturation mobility of 10.03 ± 0.64 cm 2 /Vs, I on /I off of 3.4×10 5 , low V TH of 0.14 ± 0.64 V, and small SS of 1.44 ± 0.37 V/dec. The FLA process improved the formation of M-O lattices effectively, which led to an improvement in mobility. Furthermore, the gate-bias-stress stability and time-dependent environmental stability were improved considerably by the FLA process. These results show that high-performance In 2 O 3 TFTs can be prepared at low temperatures using FLA-centered annealing technology. This work suggests that the FLA preparation method has tremendous potential for the fabrication of low-cost, high performance, and flexible TFT devices.

Highlights

Over the past decade, amorphous metal oxide semiconductors (AMOS)[1,2,3] have been studied widely as channel materials for thin-film transistors (TFTs)[4] in active-matrix displays [5, 6], biochemical sensors [7], logic circuits [8], and flexible displays owing to their superior effective electron mobility, high transparency (> 80 %) in the visible region, good atmospheric stability, excellent uniformity compared to polysilicon TFTs, and lowtemperature processing.[1, 2]
Research into TFTs based on metal oxide materials has focused mainly on amorphous binary, ternary and quaternary metal oxide materials, such as indium zinc oxide (IZO)[9], indium gallium zinc oxide (IGZO)[10, 11], zinc tin oxide (ZTO)[12, 13], indium zinc tin oxide (IZTO)[14], and indium oxide (In2O3)
The bottom-gate and top-contact TFTs were fabricated on SiO2 substrates coated with In2O3 channel films by femtosecond laser pre-annealing (FLA) at three different radiation times (30, 60, and 90 s) followed by low-temperature annealing processing

Summary

INTRODUCTION

Amorphous metal oxide semiconductors (AMOS)[1,2,3] have been studied widely as channel materials for thin-film transistors (TFTs)[4] in active-matrix displays [5, 6], biochemical sensors [7], logic circuits [8], and flexible displays owing to their superior effective electron mobility, high transparency (> 80 %) in the visible region, good atmospheric stability, excellent uniformity compared to polysilicon TFTs, and lowtemperature processing.[1, 2] Recently, research into TFTs based on metal oxide materials has focused mainly on amorphous binary, ternary and quaternary metal oxide materials, such as indium zinc oxide (IZO)[9], indium gallium zinc oxide (IGZO)[10, 11], zinc tin oxide (ZTO)[12, 13], indium zinc tin oxide (IZTO)[14], and indium oxide (In2O3). It is not a time-consuming process because of its ultrashort laser pulse and high transient intensity, resulting in lower energy cost and less damage to the metal oxide thin film.[42] The high-energy efficiency femtosecond laser is more suitable for the low-temperature annealing process of In2O3 films than other candidate technologies This is because the preparation of an In2O3 solution does not require a 2methoxyethanol/acetonitrile-based precursor. The improved high-performance solution-processed In2O3 TFTs provide an original and effective annealing method that would be suitable for flexible substrates as well as viable low-cost preparation

EXPERIMENTAL DETAILS

RESULTS AND DISCUSSION

CONCLUSIONS