Ultrahigh‐Performance Solar‐Blind Photodetectors Based on High Quality Heteroepitaxial Single Crystalline β‐Ga 2 O 3 Film Grown by Vacuumfree, Low‐Cost Mist Chemical Vapor Deposition

Abstract Due to the suitable bandgap, superior chemical and physical properties, the β‐phase gallium oxide (β‐Ga 2 O 3 ) has the great potential to fabricate the deep ultraviolet solar‐blind photodetectors (DUV PDs). However, the low material quality, high material growth cost, and insufficient device performance, are urgently required to be solved for practical applications. In this work, by using a vacuumfree, low‐cost mist chemical vapor deposition method, the high quality β‐Ga 2 O 3 single crystal films are successfully heteroepitaxially grown on (0001) sapphire substrates. X‐ray diffraction and transmission electron microscopy measurements identify the heteroepitaxial relationship with (01) β‐Ga 2 O 3 ‖(0001) sapphire. At the optimal growth temperature of 800 °C, the film shows a high quality pure β‐Ga 2 O 3 phase with the small full width at half maximum of 0.71°. Furthermore, the metal–semiconductor–metal DUV PDs are fabricated based on such single crystal β‐Ga 2 O 3 films, which exhibit excellent photoelectric performance. A very high photoresponsivity 22 000 A W −1 under 254 nm light illumination, which corresponds to a quantum efficiency of 1.07 × 10 7 % and a high detectivity of 1.1 × 10 16 Jones, almost the highest ever reported. The low‐cost film heteroepitaxial growth method and the ultrahigh device performance pave an alternative way for the fabrication of high‐performance β‐Ga 2 O 3 solar‐blind DUV PDs.