Fabrication and characterization of indium-tin-oxide/GaN visible-blind UV detectors

Abstract

We report the fabrication and characterization of visible-blind GaN-based UV photodetectors with indium-tin-oxide (ITO)/GaN Schottky junctions. We have systematically studied the optimal growth conditions for the ITO layers. Responsivity of 0.041 A/W was obtained for the optimised ITO/GaN UV detectors at 350nm. The I-V characteristics show that the reverse leakage currents of the devices are strongly dependent on the deposition conditions of the ITO. The experimental results indicate that interfacial traps play an important role on the optoelectronic properties of the devices. To improve the ITO/GaN interface, a thin Ni layer was deposited between the ITO and the GaN. Our results show that this leads to significant improvements in the leakage current, low-frequency excess noise and the UV-to-visible rejection ratio. © 2006 WILEY-VCH Verlag GmbH & Co. KGaA.