Effect of gas ambient and varying RF sputtering power for bandgap narrowing of mixed (ZnO:GaN) thin films for solar driven hydrogen production

► Mixed (ZnO:GaN) thin film for solar driven hydrogen production. ► The mixed (ZnO:GaN) thin films deposited under Ar gas ambient failed to reduce the bandgap. ► Whereas, (ZnO:GaN) thin films grown under mixed O2 and N2 gas ambient showed bandgap reduction. ► The bandgap of (ZnO:GaN) thin films was tuned by varying the RF power. ► Enhanced crystallinity and visible light absorption resulted in improved photoresponse