Characterization of composition dependence of properties of a MgNiO-based MSM structure

In this study, the effect of Mg composition on structural and optical properties of Mg_xNi_1-xO alloy thin film single crystal semiconductors as well as their implementation into Metal-Semiconductor-Metal (MSM) photodetector are studied. An 850 meV blue-shift of the bandgap is observed from 3.65 eV to 4.50 eV with increasing Mg composition from 0% to 67%. The deep ultraviolet/visible rejection ratio, which is the ratio of photosensitivity at a peak wavelength of 360 nm to that at 450 nm is found to be ∼58 for Mg composition of 67%. Mg rich (%67 Mg) alloy-based photodetector is found to have two orders smaller dark current and have higher spectral response compared to NiO-based one. Spectral responsivities for Mg_xNi_1-xO photodetectors are determined as 415 mA W⁻¹, 80 mA W⁻¹, and 5.6 mA W⁻¹ for Mg compositions of 67%, 21%, and 0% (reference-NiO), respectively. Furthermore, the detectivity of the photodetectors enhances as Mg composition increases and the highest detectivity of a magnitude of ∼10¹¹ Jones is found for the photodetector with Mg composition of 67%.