Origin of optical absorption in AlN with air voids. (23rd May 2019)

• Record Type: Journal Article
• Authors: Nagata, Kengo; Makino, Hiroaki; Yamamoto, Taiji; Saito, Yoshiki; Miki, Hisayuki
• Is Part Of: Japanese journal of applied physics. Volume 58:Number SC(2019)
• Publication Date: 2019-05-23
• Subjects: Physics -- Periodicals; 621.05
• DOI: 10.7567/1347-4065/ab1248
• Languages: English
• ISSNs: 0021-4922

Abstract

Abstract: We deposited a 4-inch crack-free aluminum nitride (AlN) layer on a flat sapphire substrate and a patterned sapphire substrate grown using metal-organic vapor phase epitaxy method. To use the 4-inch sapphire substrate, we introduce air voids in the AlN layer in the initial growth region. Moreover, we discovered that optical absorption exists in the AlN layer with air voids. The secondary ion mass spectrometry (SIMS) results show that the impurity concentrations are high at the regions where the air voids exist, though the growth conditions are same throughout the AlN layer. We considered that it is most probable that the optical absorption is mainly attributed to the complexes of Al and O. The origin of the optical absorption was identified as a deep emission band due to impurities such as carbon and oxygen around the air voids. In this study, it was possible to obtain a transparent AlN template without air voids by changing the growth conditions and the layer structure. In addition, we could further suppress the underlying layer with the air voids.