Impact of Photo-Excitation on Leakage Current and Negative Bias Instability in InSnZnO Thickness-Varied Thin-Film Transistors

Dapeng Wang; Mamoru Furuta; Shigekazu Tomai; Koki Yano

doi:10.3390/nano10091782

Impact of Photo-Excitation on Leakage Current and Negative Bias Instability in InSnZnO Thickness-Varied Thin-Film Transistors

Nanomaterials (Basel). 2020 Sep 9;10(9):1782. doi: 10.3390/nano10091782.

Authors

Dapeng Wang^{1

2

3}, Mamoru Furuta^{4

5}, Shigekazu Tomai⁶, Koki Yano⁶

Affiliations

¹ Key Laboratory of Applied Surface and Colloid Chemistry, Ministry of Education, Shaanxi Normal University, Xian 710119, China.
² Shaanxi Key Laboratory for Advanced Energy Devices; Shaanxi Engineering Lab for Advanced Energy Technology, Shaanxi Normal University, Xian 710119, China.
³ School of Materials Science and Engineering, Shaanxi Normal University, Xian 710119, China.
⁴ School of Environmental Science and Engineering, Kochi University of Technology, Kami, Kochi 782-8502, Japan.
⁵ Center for Nanotechnology in Research Institute, Kochi University of Technology, Kami, Kochi 782-8502, Japan.
⁶ Advanced Technology Research Laboratories, Idemitsu Kosan Co. Ltd., Sodegaura, Chiba 299-0293, Japan.

Abstract

InSnZnO thin-film transistors (ITZO TFTs), having high carrier mobility, guarantee the benefits of potential applications in the next generation of super-high-definition flat-panel displays. However, the impact of photo-excitation on the leakage current and negative bias stress (NBIS) of ITZO TFTs must be further explored. In this study, the ITZO thickness (T_ITZO) is designed to tailor the initial performance of devices, especially for the 100 nm T_ITZO TFT, producing excellent electrical properties of 44.26 cm²V^-1s^-1 mobility, 92 mV/dec. subthreshold swing (SS), 0.04 V hysteresis, and 3.93 × 10¹⁰ ON/OFF ratio, which are superior to those of the reported ITZO TFTs. In addition, incident light coupled with tunable photon energy is introduced to monitor the leakage current of various T_ITZO devices. The OFF-current results demonstrate that under the identical photon energy, many more electrons are photo-excited for the thicker T_ITZO TFTs. NBIS-induced V_th shift and SS deterioration in all TFTs are traced and analyzed in real time. As the T_ITZO thickens to near Debye length, the degree of degradation is exacerbated. When the thickness further increases, the notorious instability caused by NBIS is effectively suppressed. This study provides an important research basis for the application of ITZO-based TFTs in future displays.

Keywords: InSnZnO thickness; NBIS-induced instability; leakage current; oxide TFTs; photo-excitation.