Table of Contents Author Guidelines Submit a Manuscript
Journal of Nanomaterials
Volume 2014 (2014), Article ID 709018, 7 pages
Research Article

ZnO Thin-Film Transistor Grown by rf Sputtering Using Carbon Dioxide and Substrate Bias Modulation

1Department of Electrical and Computer Engineering, Ajou University, Suwon 443-749, Republic of Korea
2Materials and Structures Laboratory, Tokyo Institute of Technology, Yokohama 226-8502, Japan
3Samsung Electronics, Giheung, Hwaseong 445-330, Republic of Korea
4Smart Electronics Co., Ltd., Samdong-myeon, Ulsan 689-930, Republic of Korea

Received 16 June 2014; Revised 23 September 2014; Accepted 22 October 2014; Published 11 November 2014

Academic Editor: Songwei Lu

Copyright © 2014 Junghwan Kim et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


ZnO thin-film transistor (TFT) grown by rf magnetron sputtering in Ar/O2 atmosphere shows inferior turn-off characteristics compared to ZnO TFT grown by other methods. We thought that reactions between Zn and O2 might produce defects responsible for the poor turn-off behavior. In order to solve this problem, we studied sputtering growth in Ar/CO2 atmosphere at 450°C. During sputtering growth, we modulated substrate dc bias to control ion supply to the substrate. After growth ZnO was annealed in CO2 and O2 gas. With these methods, our bottom-gate ZnO thin-film transistor showed 4.7 cm2/Vsec mobility, on/off ratio, and –2 V threshold voltage.