Unusual Formation of Point-Defect Complexes in the Ultrawide-Band-Gap Semiconductor β-Ga_{2}O_{3}

• Published in: Physical review. X Vol. 9; no. 4; p. 041027
• Main Authors: Jared M. Johnson, Zhen Chen, Joel B. Varley, Christine M. Jackson, Esmat Farzana, Zeng Zhang, Aaron R. Arehart, Hsien-Lien Huang, Arda Genc, Steven A. Ringel, Chris G. Van de Walle, David A. Muller, Jinwoo Hwang
• Format: Journal Article
• Language: English
• Published: American Physical Society 01.11.2019
• ISSN: 2160-3308
• DOI: 10.1103/PhysRevX.9.041027

Understanding the unique properties of ultra-wide band gap semiconductors requires detailed information about the exact nature of point defects and their role in determining the properties. Here, we report the first direct microscopic observation of an unusual formation of point defect complexes within the atomic-scale structure of β-Ga_{2}O_{3} using high resolution scanning transmission electron microscopy (STEM). Each complex involves one cation interstitial atom paired with two cation vacancies. These divacancy-interstitial complexes correlate directly with structures obtained by density functional theory, which predicts them to be compensating acceptors in β-Ga_{2}O_{3}. This prediction is confirmed by a comparison between STEM data and deep level optical spectroscopy results, which reveals that these complexes correspond to a deep trap within the band gap, and that the development of the complexes is facilitated by Sn doping through increased vacancy concentration. These findings provide new insight on this emerging material’s unique response to the incorporation of impurities that can critically influence their properties.