Solar-Blind UV Photodetectors Based on GaN/AlGaN p-i-n Photodiodes

Abstract

We report on the fabrication and characterization of n-Al 0.44 Ga 0.56 N/i-Al 0.44 Ga 0.56 N/p-GaN ultraviolet solar-blind photodetectors. The diodes were fabricated by organometallic vapor phase epitaxy on low-defect-density AlGaN layers using a low-temperature interlayer technique. They present a long cutoff wavelength at 270 nm with high rejection of solar light and a responsivity of 12 mA/W. Low dark currents between 4 and 35 pA/mm 2 at -5 V have been measured. A photocurrent decay time of 14 µs has been estimated in unbiased diodes. Due to the large dynamic resistance of the diode at 0 V bias, the detector itself shows a detectivity of 1.2×10 13 cm·Hz 1/2 ·W -1 .