High-performance β-Ga2O3 solar-blind ultraviolet photodetectors epitaxially grown on (110) TiO2 substrates by metalorganic chemical vapor deposition

Abstract

High-quality (100)-oriented β-Ga2O3 films were successfully grown on (110) TiO2 substrates by metalorganic chemical vapor deposition (MOCVD) for the first time. Crystal structure, chemical composition, and surface morphology of the epitaxial β-Ga2O3 films were systematically investigated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and atomic force microscope (AFM). The epitaxial relationship between the β-Ga2O3 film and the TiO2 substrate was identified as β-Ga2O3 (100)//TiO2 (110) with β-Ga2O3 [001]//TiO2 [11‾0] and β-Ga2O3 [010]//TiO2 [001]. These material characterizations confirmed that the β-Ga2O3 film grown at 950 °C exhibited the highest crystalline quality and the smoothest surface. Furthermore, these β-Ga2O3 films were then used to fabricate solar-blind photodetectors (PDs) based on a metal-semiconductor-metal (MSM) structure. Due to the β-Ga2O3 film's best material and surface morphology grown at 950 °C, the β-Ga2O3 PDs showed the best performance with a large photocurrent of 85.3 μA, a responsivity of 2.56 A W−1, and a detectivity of 5 × 1011 Jones. This work explores a new TiO2 substrate for the heterogeneous epitaxy of β-Ga2O3 films, and opens the door for the development of β-Ga2O3 photonics and electronics on cost-effective mass-producible substrates.