Alloying Ga₂O₃ with Fe₂O₃ on Corundum‐Structured rh‐ITO by Mist CVD and Its Demonstration of Photodetector and Photoelectrode Applications

Abstract

Corundum‐structured α‐Ga2O3 is an ultrawide bandgap semiconductor with a bandgap of 5.3 eV and is actively investigated for applications in power electronics and optoelectronic devices. This study explores bandgap engineering of α‐Ga2O3 to broaden its application field. By alloying α‐Fe2O3, which has the same corundum structure as α‐Ga2O3, the bandgap can be tuned from 2.2 to 5.3 eV. This allows α‐Ga2O3 to be used as a visible‐light‐driven photocatalyst by narrowing its bandgap. Herein, (Ga, Fe)2O3 alloy thin films are grown on corundum‐structured indium tin oxide (rh‐ITO) electrodes for photocatalytic applications. X‐ray diffraction 2θ–ω measurements reveal that corundum‐structured α‐(Ga, Fe)2O3 thin films are grown on rh‐ITO electrodes with up to ≈20% Ga composition. At higher Ga compositions, orthorhombic ε‐GaFeO3 and amorphous Ga2O3 are observed on the rh‐ITO electrode. Photoresponsivity measurements using a photodetector structure confirm that the thin films exhibit visible light sensitivity upon alloying Fe2O3 with Ga2O3. Linear sweep voltammetry measurements indicate that the α‐(Ga, Fe)2O3 thin film grown on rh‐ITO can serve as a visible light‐driven photoelectrode. The findings contribute to the bandgap engineering of α‐Ga2O3 and its application in photocatalysis.