Ultraviolet photodetectors based on MgZnO thin film grown by RF magnetron sputtering

We demonstrate the growth of high quality, single phase, wurtzite Mg_xZn_1-xO thin films on p-type Si (111) substrate by magnetron sputtering using Mg_0·3Zn_0.7O as target and no buffer layer is used for the growth. The films are highly oriented along the c-axis and have nanorod-like morphology. The Mg content in Mg_xZn_1-xO films varies in a large range (40.7–51 at. %) by changing the substrate temperature from room temperature to 250 °C. The Mg_xZn_1-xO films maintain the hexagonal phase up to 150 °C substrate temperature and the Mg content at this temperature is 43.7 at.%. The heterostructures of Mg_xZn_1-xO/Si are fabricated into metal-semiconductor-metal photodetectors. The signal to noise ratio (S/N) is as high as 4.3 × 10⁴% at 2 V bias under 325 nm laser at relatively low laser illumination intensity (2.77 mW), and the output photocurrent increases with the increase in the UV illumination intensity at both − 10 V and + 10 V biased voltage. The photocurrents increase with the rise in the illumination intensity. The peak responsivity is 4.6 A/W at 292 nm with a cutoff wavelength of 305 nm and at 9 V bias voltage.