Preprint Article Version 2 NOT YET PEER-REVIEWED

High Responsivity in GaN Ultraviolet Photodetector Achieved by Growing on a Periodic Trapezoid Column-Shape Patterned Sapphire Substrate

Department of Electronic Engineering, Cheng Shiu University, Kaohsiung 83347, Taiwan
Institute of Microelectronics, Department of Electrical Engineering Center for Micro/Nano Science and Technology, Advanced Optoelectronic Technology Center, National Cheng Kung University, Tainan 701, Taiwan
Department of Electronics Engineering and Computer Sciences, Tung Fang Design Institute, Kaohsiung 82941, Taiwan
Version 1 : Received: 30 September 2016 / Approved: 30 September 2016 / Online: 30 September 2016 (09:40:28 CEST)
Version 2 : Received: 18 October 2016 / Approved: 18 October 2016 / Online: 18 October 2016 (08:19:48 CEST)

A peer-reviewed article of this Preprint also exists.

Journal reference: GaN-Based MSM Photodetectors Prepared on Patterned Sapphire Substrates 2008, 20, 22
DOI: 10.1109/LPT.2008.2004814


GaN ultraviolet photodetector with metal-semiconductor-metal structure is achieved by growing on a periodic trapezoid column-shape patterned sapphire substrate using metalorganic chemical vapor deposition. Under 5-V reverse bias, the photodetector fabricated on such patterned sapphire substrate exhibits a lower dark current, a higher photocurrent, and a 476 % enhancement in the maximum responsivity as compare with those of the photodetector fabricated on conventional flat sapphire substrate. It is also found that the much larger UV-to-visible rejection ratio and the fact that responsivity drops in a smaller cut-off region are observed from photodetector fabricated by using a periodic trapezoid column-shape patterned sapphire substrate. These phenomena may all be attributed to the reduction of threading dislocation density and the improved quality of GaN film, as well as the internal reflection and/or scattering effect on the interface between GaN film and the periodic trapezoid column-shape pattern of the substrate.

Subject Areas

GaN ultraviolet photodetector; periodic trapezoid column-shape patterned sapphire substrate; responsivity; UV-to-visible rejection ratio

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