High responsivity tin gallium oxide Schottky ultraviolet photodetectors

Abstract

The authors report on high spectral responsivity (SnxGa1 − x)2O3 Schottky UV photodetectors grown by plasma-assisted molecular beam epitaxy on β-Ga2O3 substrates. Schottky devices exhibited peak responsivities ranging from 49 to 194 A/W, with peak responsivity and wavelength position increasing systematically for higher Sn concentration from x = 0.01 to 0.18. Dark currents for the devices ranged from <1 nA to 3 μA with rise and fall times in the 0.21–3 s time range, with slower response times likely due to photoconductive gain caused by trapped holes. Incorporation of up to 18% Sn into the tin gallium oxide (TGO) devices resulted in a redshift in the peak responsivity position, ranging from 5.19 to 4.86 eV, demonstrating tunability within the UV-C spectral region through Sn concentration adjustment. The authors believe this to be the highest reported responsivity for a planar Ga2O3-based Schottky photodetector to date, suggesting that TGO based UV-C Schottky detectors are an attractive approach toward deep-UV sensing applications.