β-Ga2O3 thin films on sapphire pre-seeded by homo-self-templated buffer layer for solar-blind UV photodetector

•The wide bandgap semiconductor gallium oxide thin films were grown by molecular beam epitaxy.•The high temperature grown homo-templated buffer layer was introduced to improve the crystalline quality of the hetero-epitaxial gallium oxide thin films.•The solar-blind ultraviolet photoconductive detectors were fabricated and tested.

Gallium oxide thin films were grown on c-plane sapphire substrate by molecular beam epitaxy. The homo-self-templated buffer layer was introduced for the gallium oxide thin film growth, and accordingly the FWHM of the on-axis (2¯01) β-Ga2O3 diffraction peak of the X-ray diffraction rocking curve was reduced from 1.9° to 0.9°, proving an improvement in the crystalline quality of β-Ga2O3 thin film. In addition, the planar-geometry metal–semiconductor–metal photoconductive detectors (PDs) were manufactured by using the 100 nm β-Ga2O3 thin films. Accordingly, the PDs based on the β-Ga2O3 thin films with homo-self-templated buffer layer performed obviously improved device properties, such as small dark current of 0.04 nA, high photo- to dark- current ratio in the order of 104, large photoresponsivity of 259 A/W, high external quantum efficiency of 7.9 × 104%, weak persistent photoconductivity, and excellent solar-blind UV responsivity. Hence, it is reasonable to believe that the β-Ga2O3 thin film grown with homo-self-templated buffer layer is a promising candidate for the application in solar-blind UV camera.