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.

In situ atomic-resolution study of transformations in double polymorph γ/β-Ga2O3 structures

“…Similar APBs in the γ-Ga 2 O 3 spinel structure have been reported in the literature. 8,27–29 Thus, in the initial stage, the samples used in this study are representative examples of the double γ/β-Ga 2 O 3 polymorph structures. No apparent differences were detected in the quality of the γ-Ga 2 O 3 produced either by Si or Au implants.…”

Synthesis of InAl-alloyed Ga2O3 nanowires for self-powered ultraviolet detectors by a CVD method

“…In order to improve the detection performance, people oen regulated the optical and electrical characteristics of Ga 2 O 3 by introducing doping elements and constructing heterojunctions. [33][34][35][36][37][38] For example, Zhu et al 39 reported a Schottky junction UV photodetector spun with MXene on Ga 2 O 3 nanowire, which is essentially MSM structured. Usman et al 40 reported a (In 0.26 Ga 0.74 ) 2 O 3 photodetector based on microwave irradiation assisted deposition technology, which is still a photoconductive device.…”