1. Defect-dependent environmental stability of high mobility transparent conducting In-doped CdO.
- Author
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Wu, Shan, Zha, Shen Jie, Zhang, Yang, Liu, Gui Shan, Chen, Xiong Jing, Li, Zhan Hua, Ho, Chun Yuen, Deng, Bei, Yu, Kin Man, and Liu, Chao Ping
- Subjects
PASSIVATION ,THIN films ,ELECTRON mobility ,OPTOELECTRONIC devices ,CRYSTAL grain boundaries ,HUMIDITY - Abstract
Highly degenerate n-type CdO with high electron mobility is a promising transparent conducting oxide (TCO) for optoelectronic devices utilizing a spectrum in the Vis-NIR range. In particular, it has been shown that doped CdO thin films can show much superior transparency of >80% in the NIR region compared to conventional transparent conducting oxide (e.g., Sn-doped In
2 O3 ) thin films with a similar sheet resistance. However, CdO thin films typically experience rapid degradation in their electron mobilities when exposed to environmental conditions with H2 O moisture. Here, we studied the effects of thermal annealing on the environmental stability of In-doped CdO (CdO:In) using a combination of different analytical techniques. CdO:In thin films with different In concentration (0%–8.3%) synthesized by magnetron sputtering were subjected to different post-thermal annealing (PTA) and then aged in different environmental conditions with varying relative humidity (RH) in the range of 0%–85%. Our results reveal that the degradation of CdO:In thin films can be primarily attributed to the oxygen vacancy-related defects at the grain boundaries, which can readily react with the OH− in the moisture. The moisture induced degradation can be mitigated by appropriate PTA at high temperatures (>400 °C) where grain boundary defects, primarily associated with Cd vacancies, can be passivated through hydrogen (H), thus enhancing their environmental stability. The present study provides a comprehensive understanding of the instability mechanisms and defect passivation in transparent conducting CdO:In thin films, which can also be relevant for other wide gap oxides. [ABSTRACT FROM AUTHOR]- Published
- 2024
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