Characterization of hexagonal ɛ-Ga1.8Sn0.2O3 thin films for solar-blind ultraviolet applications

Ga1.8Sn0.2O3 thin films were deposited on c-plane Al2O3 (0001) substrates by laser molecular beam epitaxy technology. Well crystallized (002) oriented ɛ-phase Ga1.8Sn0.2O3 thin films were obtained at the substrate temperature above 750 °C and the oxygen partial pressure more than 5 × 10−3 Pa. The band-gap slightly shrinks with Sn4+ ions incorporated into Ga3+ sites, showing an excellent solar-blind ultraviolet (UV) characteristic. The conductivity of hexagonal ɛ-Ga1.8Sn0.2O3 films is very low in the dark, and permitting the design and fabrication of solar-blind photodetector. The photodetector exhibits obvious photo-response under 254 nm UV light irradiation, and it increases in photocurrent with both the rise of applied bias and optical input power. The results suggest that ɛ-Ga1.8Sn0.2O3 thin film is a promising candidate for using in solar-blind photodetectors.