Affiliation:
1. Department of Physics Centre for Materials Science and Nanotechnology University of Oslo PO Box 1048 Blindern Oslo N‐0316 Norway
2. HUN‐REN Centre for Energy Research Institute of Technical Physics and Materials Science Konkoly‐Thege M. u. 29–33 Budapest 1121 Hungary
Abstract
AbstractGallium oxide (Ga2O3) can be crystallized in several polymorphs exhibiting different physical properties. In this work, polymorphic structures consisting of the cubic defective spinel (γ) film on the top of the monoclinic (β) substrate are fabricated by disorder‐induced ordering, known to be a practical way to stack these polymorphs together. Such bilayer structures are annealed to investigate optical properties and phase transformations. Specifically, photoluminescence and diffuse reflectance spectroscopy are combined with transmission electron microscopy, Rutherford backscattering/channeling spectrometry and X‐ray diffraction to monitor the evolutions. As a result, a two‐stage annealing kinetics is observed in γ/β Ga2O3 bilayers associated with the epitaxial γ‐to‐β regrowth at the interface at temperatures below 700 °C and a non‐planar γ‐to‐β phase transformation starting at higher temperatures. Thus, the present data enhance understanding of the polymorphism in Ga2O3, interconnecting the phase transformation kinetics with the evolution of the optical properties.