Highly solar-blind ultraviolet selective metal-semiconductor-metal photodetector based on back-illuminated AlGaN heterostructure with integrated photonic crystal filter

Applied Physics Letters, Volume 118, Issue 14, April 2021. In this paper, we proposed a back-illuminated metal-semiconductor-metal AlGaN heterostructure solar-blind ultraviolet (UV) photodetector integrated with a SiO2/Si3N4 one-dimensional photonic crystal (1D PC). The light absorption outside solar-blind ultraviolet caused by impurity and defect energy levels is significantly suppressed by the 1D PC. The fabricated device exhibits extremely low dark current of 2 pA at 20 V applied voltage, where light/dark current ratio exceeds 4000. Meanwhile, the photodetector demonstrates a manifest narrow-band solar-blind detection property. The optical modulations of heterostructure energy-band engineering and photonic crystal filter both contribute to the solar-blind absorbing selectivity. In addition, the finger-scaling effects are also investigated based on carrier transport mechanism. These results are anticipated to promote the evolution on design and fabrication of solar-blind UV photodetector.