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 degrees 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 degrees 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 degrees 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 degrees 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).