Metal–Semiconductor–Metal AlN Mid-Ultraviolet Photodetectors Grown by Magnetron Reactive Sputtering Deposition

Metal–semiconductor–metal (MSM) AlN mid-ultraviolet (mid-UV) photodetectors were fabricated. AlN layers were grown on GaN substrates by magnetron reactive sputtering deposition. The AlN photodetectors exhibited a high responsivity at wavelengths from 210 nm to 190 nm, and the response tails off at a wavelength of 220 nm. The responsivities at 200 nm at biases of 5 V and 10 V were 1.08 and 3.51 A/W, respectively. When the reverse voltage was higher than 7 V, responsivity increased almost linearly with reverse voltage. The responsivity at 25 V was calculated to be approximately 14.9 A/W.