Fabrication, properties, and photodetector of β-(AlxGa1-x)2O3/GaN heteroepitaxial films grown by MOCVD

Abstract

In this paper, β-(AlxGa1-x)2O3 heteroepitaxial films with different Al content were successfully prepared on p-GaN substrates by MOCVD method. When the “x” values are in a range of 0–0.38, the (AlxGa1-x)2O3 grown on p-GaN is an epitaxial film, maintaining the lattice structure of β-Ga2O3, and presenting an adjustable bandgap of 5.0–5.93 eV. When x = 0.45, the film is amorphous, and present a low bandgap of ∼5.73 eV due to the band tail formed by a large number of defects. φ scanning, HRTEM and SAED results showed that the prepared film was a six-fold domain structure and had an epitaxial relationship with the substrate of β-(AlxGa1-x)2O3 (2‾01) || GaN (0001) with β-(AlxGa1-x)2O3 [102] || GaN <1-100>. The photodetector (PD) based on β-(AlxGa1-x)2O3/GaN p-n junction presents high photoresponsivity (0.045 A/W) at 218 nm. The wavelength is far lower than the optimal responsive wavelength (254 nm) of β-Ga2O3 in previous reports, meaning that β-(AlxGa1-x)2O3 can be used to fabricate shorter wavelength UV photodetector.