MOCVD growth of MgGa2O4 thin films for high-performance solar-blind UV photodetectors

Abstract

Epitaxial MgGa2O4 thin films with a bandgap of 5.18 eV were grown on the c-plane sapphire substrate by using metal organic chemical vapor deposition. The structure, optical, electronic, and optoelectronic properties of MgGa2O4 thin films have been investigated before and after high-temperature annealing in an oxygen or nitrogen atmosphere. In particular, the O2-annealed MgGa2O4 thin film reveals a high crystalline quality and a low concentration of oxygen vacancies. Moreover, a quick response speed (tr = 20 ns, td = 400 ns), a low dark current (∼17 pA at 10 V), and a high UV/Visible rejection ratio (>105) can be demonstrated in the O2-annealed MgGa2O4 photodetector, indicating the excellent solar-blind ultraviolet (SBUV) photodetection characteristics. The effect of annealing atmosphere on the photoelectric properties of the film and its physical mechanism were studied. This research provides an effective way to realize high-performance SBUV photodetectors and opens up the application of MgGa2O4 spinel in the field of semiconductor optoelectronic and microelectronic devices.