Mg and Al-induced phase transformation and stabilization of Ga2O3-based γ -phase spinels
Abstract
Ga2O3 films were deposited on (100) MgAl2O4 spinel substrates at 550, 650, 750, and 850 °C using metal-organic chemical vapor deposition and investigated using x-ray diffraction and transmission electron microscopy. A phase-pure γ-Ga2O3-based material having an inverse spinel structure was formed at 850 °C; a mixture of the γ-phase and β-Ga2O3 was detected in films grown at 750 °C. Only β-Ga2O3 was determined in the films deposited at 650 and 550 °C. A β- to γ-phase transition occurred from the substrate/film interface during growth at 750 °C. The growth and stabilization of the γ-phase at the outset of film growth at 850 °C was affected by the substantial Mg and Al chemical interdiffusion from the MgAl2O4 substrate observed in the energy-dispersive x-ray spectrum. Atomic-scale investigations via scanning transmission electron microscopy of the films grown at 750 and 850 °C revealed a strong tetrahedral site preference for Ga and an octahedral site preference for Mg and Al. It is postulated that the occupation of these atoms in these particular sites drives the β-Ga2O3 to γ-phase transition and markedly enhances the thermal stability of the latter phase at elevated temperatures.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Jul 03, 2023
- Source ID
- 10.1063/5.0145076
Entities
People
- Chengchao Xu
- Jingyu Tang
- K.Q. Xiao
- Kunyao Jiang
- Lisa M. Porter
- Robert F Davis
- Stephen House
Organizations
- Air Force Office of Scientific Research
- Carnegie Mellon University
- Sandia National Laboratories
- University of Pittsburgh