Ta-Doped Ga₂O₃ Epitaxial Films on Porous p-GaN Substrates: Structure and Self-Powered Solar-Blind Photodetectors

Self-powered solar-blind Ga 2 O 3 -based photodetectors based on polycrystalline films rather than single-crystal films have been widely studied. In this work, Ta-doped Ga 2 O 3 single-crystal films deposited on porous p-type GaN substrates by metal–organic chemical vapor deposition (MOCVD) were prepared as self-powered solar-blind photodetectors. As the porosity of the substrate increased, the crystal quality of the deposited film was optimized, probably resulting from the reduction of threading dislocations (TDs). The epitaxial relation between the β-Ga 2 O 3 single-crystal film and the GaN substrate was β-Ga 2 O 3 (2̅01) || GaN (0001) with β-Ga 2 O 3 [010] || GaN <21̅1̅0>. Compared with the photodetector based on the β-Ga 2 O 3 grown on as-grown p-GaN, the detector based on the β-Ga 2 O 3 deposited on porous p-GaN presented fast rise/decay times (0.41 s/0.34 s) and high photoelectric responsivity (3.54 × 10 –2 A/W) at 222 nm without bias because of the electron–hole pairs separated by the in-built electric field rapidly, indicating good solar-blind response ability.