Continuous V-Grooved AlGaN/GaN Surfaces for High-Temperature Ultraviolet Photodetectors

Abstract

Three-dimensional heterostructured AlGaN/GaN ultraviolet (UV) photodetectors were microfabricated using V-grooved silicon(111) surfaces and metal organic chemical vapor deposition. This novel sensor platform enabled an increase in sensitivity and operation at high temperatures (up to 200°C). More specifically, texturizing the highly conductive 2-D electron gas using the V-groove sensor surfaces, resulted in higher photodetector sensitivity (57.4% increase at room temperature and 139% at 200°C) compared with conventional designs on planar substrates due to the increased absorption of incident UV light (optical trapping). In addition, a 53% reduction in electrical resistance at room temperature and 27.3% at 200°C were observed due to the increased surface area. The decay time for the non-exponential persistent photoconductivity decreased significantly from 327 to 34 sec as the temperature increased from room temperature to 200°C as a result of the accelerated electron-hole pair recombination (generation) rate. These results support the use of textured AlGaN/GaN sensor platforms for UV detection in harsh environments (e.g., downhole, combustion, and space).