Alloying Ga 2 O 3 with Fe 2 O 3 on Corundum‐Structured rh‐ITO by Mist CVD and Its Demonstration of Photodetector and Photoelectrode Applications

Corundum‐structured α‐Ga 2 O 3 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‐Ga 2 O 3 to broaden its application field. By alloying α‐Fe 2 O 3 , which has the same corundum structure as α‐Ga 2 O 3 , the bandgap can be tuned from 2.2 to 5.3 eV. This allows α‐Ga 2 O 3 to be used as a visible‐light‐driven photocatalyst by narrowing its bandgap. Herein, (Ga, Fe) 2 O 3 alloy thin films are grown on corundum‐structured indium tin oxide (rh‐ITO) electrodes for photocatalytic applications. X‐ray diffraction 2 θ – ω measurements reveal that corundum‐structured α‐(Ga, Fe) 2 O 3 thin films are grown on rh‐ITO electrodes with up to ≈20% Ga composition. At higher Ga compositions, orthorhombic ε‐GaFeO 3 and amorphous Ga 2 O 3 are observed on the rh‐ITO electrode. Photoresponsivity measurements using a photodetector structure confirm that the thin films exhibit visible light sensitivity upon alloying Fe 2 O 3 with Ga 2 O 3 . Linear sweep voltammetry measurements indicate that the α‐(Ga, Fe) 2 O 3 thin film grown on rh‐ITO can serve as a visible light‐driven photoelectrode. The findings contribute to the bandgap engineering of α‐Ga 2 O 3 and its application in photocatalysis.