Operational stability of solution-processed indium-oxide thin-film transistors: Environmental condition and electrical stress

• Published in: Journal of the Korean Physical Society 2018, 72(1), , pp.151-158
• Main Authors: Baang, Sungkeun, Lee, Hyeonju, Zhang, Xue, Park, Jaehoon, Kim, Won-Pyo, Ko, Young-Woong, Piao, Shang Hao, Choi, Hyoung Jin, Kwon, Jin-Hyuk, Bae, Jin-Hyuk
• Format: Article
• Language: English
• Subjects: Contact stresses; Electric contacts; Electron microscopy; Electrons; Grain boundaries; Indium; Indium oxides; Majority carriers; Mathematical and Computational Physics; Particle and Nuclear Physics; Photoelectric emission; Physics; Physics and Astronomy; Semiconductor devices; Spin coating; Structural stability; Theoretical; Thermogravimetric analysis; Thin film transistors; Threshold voltage; Transistors; Water chemistry; 물리학
• ISSN: 0374-4884; 1976-8524
• DOI: 10.3938/jkps.72.151

We investigate the operational stability of bottom-gate/top-contact-structured indium-oxide (In 2 O 3 ) thin-film transistors (TFTs) in atmospheric air and under vacuum. Based on the thermogravimetric analysis of the In 2 O 3 precursor solution, we utilize a thermal annealing process at 400 °C for 40 min to prepare the In 2 O 3 films. The results of X-ray photoemission spectroscopy and field-emission scanning electron microscopy show that the electron is the majority carrier in the In 2 O 3 semiconductor film prepared by a spin-coating method and that the film has a polycrystalline morphology with grain boundaries. The fabricated In 2 O 3 TFTs operate in an n -type enhancement mode. When constant drain and gate voltages are applied, these TFTs in atmospheric air exhibit a more acute decay in the drain currents with time compared to that observed under vacuum. In the positive gate-bias stress experiments, a decrease in the field-effect mobility and a positive shift in the threshold voltage are invariably observed both in atmospheric air and under vacuum, but such characteristic variations are also found to be more pronounced for the atmospheric-air case. These results are explained in terms of the electron-trapping phenomenon at the grain boundaries in the In 2 O 3 semiconductor, as well as the electrostatic interactions between electrons and polar water molecules.