Realization of Erythemal UV Detectors Using Ni/GaN Schottky Junctions

In this paper, we present the design, fabrication, and characterization of a novel UV photodetector with a cutoff wavelength of 300 nm without utilizing AlGaN-based junctions or multilayer optical filters. The active region of the device consists of a pair of Ni/GaN Schottky junctions connected in antiparallel configuration. Each junction, by itself, exhibits a cutoff wavelength of 360 nm-characteristic of band-to-band absorption in GaN. A polymer film, which exhibits strong absorption of photons at about 320 nm and below, is deposited on top of one of the Schottky junctions. Due to the antiparallel connection of the two junctions, the overall photocurrent is the difference between the two individual junctions. Our experimental results clearly demonstrate the photocurrent cancellation effect. Using this novel design, we have successfully pushed the cutoff wavelength of the complete device down to approximately 300 nm.