Probing Bond Length and Compositional Disorder in β‐(AlxGa1‐x)2O3 Alloys Using Extended X‐ray Absorption Fine Structure Spectroscopy

The local structure of β‐(AlxGa1‐x)2O3 alloys for various Al contents has been determined from extended X‐ray absorption fine structure spectroscopy (EXAFS) performed at the Ga K‐edge. A model to fit the experimental EXAFS data of the monoclinic β‐(AlxGa1‐x)2O3 alloy has been suggested to independently determine relevant local structure parameters. An increase in compositional disorder corresponding to the near neighbours (NNs) for lower Al contents establishes that the Al atom does occupy tetrahedron atomic sites in addition to octahedron sites even for smaller Al contents. The NNs and next‐nearest neighbours (NNNs) bond lengths corresponding to tetrahedron and octahedron coordinated Gallium (Ga) atoms with the surrounding Oxygen (O) atoms as well as tetrahedron‐tetrahedron/octahedron‐octahedron coordinated Ga‐Ga atoms on average display a decreasing trend with the Al content up to x=33.3% and then they do not change much with a further increase in Al content. While, tetrahedron‐octahedron coordinated Ga‐Ga atoms move far from each other with the Al content up to x=33.3% and then it does not change much. The physical picture derived from the EXAFS analysis indicates the creation of tetrahedra and octahedra sublattices at the local level for β‐(AlxGa1‐x)2O3 alloys, and their sizes decrease, but they move far apart from each other up to a certain Al content. Thereafter, their sizes and the distance between them do not change much. Thus, the EXAFS results provide a clear insight into the evolution of the local structure of β‐(AlxGa1‐x)2O3 alloys with the Al content, which may be useful for a better understanding of their physical properties.This article is protected by copyright. All rights reserved.