High-responsivity UV detectors based on MgNiO films grown by magnetron sputtering

We have grown high-quality MgNiO films at 300 .C and 400 .C by the radio frequency magnetron sputtering. Transmittance measurements show that the absorption edges of the films grown at 300 .C and 400 .C are at 251 nm and 227 nm, respectively. We have deduced that the MgNiO film grown at a higher temperature has a higher Mg content and bigger bandgap. The XRD results confirm the deduction. Based on those films, we have fabricated UV detectors and measured the spectral response. The peak responsivities of the detectors with MgNiO films grown at 300 .C and 400 .C are located at 260 nm and 230 nm and are about 2.56A/W and 2.3A/W, respectively. The corresponding UV to visible rejection ratios (250 nm/500 nm) are 640 and 530, respectively. The large UV to visible rejection ratio and the high responsivity make the MgNiObased detector a very encouraging candidate in the application of visible-blind and solar-blind UV light detection.