Elaboration of near‐valence band defect states leading deterioration of ambipolar operation in SnO thin‐film transistors
Makoto Minohara,
Shutaro Asanuma,
Hidehiro Asai,
Yuka Dobashi,
Akane Samizo,
Yasuhisa Tezuka,
Kenichi Ozawa,
Kazuhiko Mase,
Izumi Hase,
Naoto Kikuchi,
Yoshihiro Aiura
Affiliations
Makoto Minohara
Research Institute for Advanced Electronics and Photonics National Institute of Advanced Industrial Science and Technology (AIST) Tsukuba Ibaraki Japan
Shutaro Asanuma
Device Technology Research Institute National Institute of Advanced Industrial Science and Technology (AIST) Tsukuba Ibaraki Japan
Hidehiro Asai
Device Technology Research Institute National Institute of Advanced Industrial Science and Technology (AIST) Tsukuba Ibaraki Japan
Yuka Dobashi
Department of Materials Science and Technology Tokyo University of Science Katsushika Tokyo Japan
Akane Samizo
Department of Materials Science and Technology Tokyo University of Science Katsushika Tokyo Japan
Yasuhisa Tezuka
Graduate School of Science and Technology Hirosaki University Hirosaki Aomori Japan
Kenichi Ozawa
Department of Chemistry Tokyo Institute of Technology Meguro Tokyo Japan
Kazuhiko Mase
Institute of Materials Structure Science High Energy Accelerator Research Organization (KEK) Tsukuba Ibaraki Japan
Izumi Hase
Research Institute for Advanced Electronics and Photonics National Institute of Advanced Industrial Science and Technology (AIST) Tsukuba Ibaraki Japan
Naoto Kikuchi
Research Institute for Advanced Electronics and Photonics National Institute of Advanced Industrial Science and Technology (AIST) Tsukuba Ibaraki Japan
Yoshihiro Aiura
Research Institute for Advanced Electronics and Photonics National Institute of Advanced Industrial Science and Technology (AIST) Tsukuba Ibaraki Japan
Abstract Ambipolar transistor operation in SnO thin‐film transistors (TFTs) is a promising character for future practical application, such as in integrated logic devices based on oxide semiconductors, because of its ability to develop them using a single material. However, there are only a few reports that demonstrate the apparent ambipolar operation for SnO TFTs owing to the insufficient knowledge on the reasons for deterioration of device performance. Although a previous study controls the operation mode of SnO TFTs [A. W. Lee et al. Adv. Electron. Mater. 6, 200742 (2020)], an additional passivating layer is required; however, it hinders the benefits of SnO usage. In this study, we provide the mechanism of deterioration of the ambipolar character of bare SnO TFTs, that is, the origin of defect states near the valence band maximum (near‐VB defect). Comprehensive spectroscopic approaches including photoemission, X‐ray emission, and X‐ray absorption spectroscopy, reveal that near‐VB defect states originate from oxygen vacancies, existing at the surface, and also in the entire SnO film. This finding is useful to improve device performance for obtaining the ambipolar operation of SnO TFTs.
