Local structure and ordering of Al atoms in AlxGa1−xN epilayers

Abstract

In this study, we investigate the local structure of aluminum (Al) in a comprehensive series of AlxGa1−xN epilayers, where the Al concentration spans from the dilute limit to 100%. We analyze grazing incidence Al K-edge tender x-ray absorption spectroscopy data using both linear combination fitting based on reference limit spectra and full quantitative analysis. The results indicate deviations from random cation distribution with varying signs within the explored concentration range. Additionally, we observe a reduction in cationic interatomic distances over a wide concentration range, which contrasts with some previous studies conducted at hard x-ray absorption edges.

AlN interlayer-induced reduction of dislocation density in the AlGaN epilayer

“…21–24 In recent studies, attention has been directed towards the local structure and ordering of Al atoms in thick AlGaN epilayers. 25 However, to our surprise, the majority of this recent literature overlooks the defect state, specifically dislocation densities, in the AlGaN layer, 21,22 which might give interesting answers about both the electrical and optical properties of the whole heterostructure. 8 Thus, understanding the defect state within the AlGaN epilayer will aim to contribute to the current body of knowledge.…”