Impact of selective thermal etching in mixed H2/NH3 atmosphere on crystal quality of AlGaN/GaN heterostructures. (18th February 2021)

• Record Type: Journal Article
• Authors: Yoshiya, Yuki; Hoshi, Takuya; Sugiyama, Hiroki; Matsuzaki, Hideaki
• Is Part Of: Japanese journal of applied physics. Volume 60:Number SB(2021)
• Publication Date: 2021-02-18
• Subjects: selective thermal etching -- GaN HEMTs -- polarity -- epitaxial-layer transfer technique; Physics -- Periodicals; 621.05
• DOI: 10.35848/1347-4065/abdf72
• Languages: English
• ISSNs: 0021-4922

Abstract

Abstract: We investigated the impact of selective thermal etching in a mixed hydrogen and ammonia atmosphere on the crystal quality and electrical characteristics of Ga- and N-polar AlGaN/GaN heterostructures. It was revealed that the etching rate of N-polar GaN is lower than that of Ga-polar GaN under our experimental conditions, and they showed a similar dependence on process temperature with almost the same activation energies. We demonstrated the use of a thin AlGaN layer as a selective etching stopper for both Ga- and N-polarity. The AlGaN stoppers exhibited a smooth surface after etching the GaN layer above them. As for the electrical characteristics, there was no significant degradation in the mobility of the two-dimensional electron gas. The results indicate that selective thermal etching is a promising technique for device fabrication and is especially suitable for precise GaN layer removal when GaN-based devices are fabricated with an epitaxial layer transfer technique.