MgZnO grown by molecular beam epitaxy on N-Type β-Ga2O3 for UV Schottky barrier solar-blind photodetectors

MgZnO is an attractive semiconductor alloy for UV optoelectronic and electronic devices. Due to recent progress and availability of high quality Ga 2 O 3 substrates and its high solar-blind bandgap of ~4.9 eV, it is desirable to investigate its application for solar-blind applications as a potential substrate alternative to sapphire for MgZnO. MgZnO alloys have been grown using plasma-assisted molecular beam epitaxy on Sn doped n-type (010) β-Ga 2 O 3 substrates. It was found MgZnO growth with a MgO buffer layer has a rocksalt lattice structure. In-situ RHEED observations show that the sample grown with a MgO buffer shows two-dimensional growth and a surface roughness with root-mean-square (RMS) below 2 nm. On the other hand, MgZnO grown without a MgO buffer has a mixed phase of rocksalt and wurtzite lattice structures. Additionally, as the initial step for the fabrication of tunable wavelength solar-blind photodetectors, Schottky barrier photodetectors have been fabricated, demonstrating zero (0 V) bias responsivity of 0.1 μA/W (rocksalt MgZnO), 0.7 μA/W (mixed phase MgZnO) and 1.3 μA/W (mixed phase MgZnO) at 230 nm, 310 nm and 335 nm, respectively.