This paper presents the comparative analysis of influence of doping level and doping profile of the active region on zero bias photoresponse characteristics of GaN-based p-i-n ultraviolet (UV) photodetectors operating at front- and back-illuminated. A two dimensional physically-based computer simulation of GaN-based p-i-n UV photodetectors is presented. We implemented GaN material properties and physical models taken from the literature. It is shown that absorption layer doping profile has notable impacts on the photoresponse of the device. Especially, the effect of doping concentration and distribution of the absorption layer on photoresponse is discussed in detail. In the case of front illumination, comparative to uniform n-type doping, the device with n-type Gaussian doping profiles at absorption layer has higher responsivity. Comparative to front illumination, back illuminated detector with p-type doping profiles at absorption layer has higher maximum photoresponse, while the Gaussian doping profiles have a weaker ability to enhance the device responsivity. It is demonstrated that electric field distribution, mobility degradation, and recombinations are jointly responsible for the variance of photoresponse. Our work enriches the understanding and utilization of GaN based p-i-n UV photodetectors.
We report on two-dimensional (2D) numerical simulations of photoresponse characteristics for GaN based p-i-n ultraviolet (UV) photodetectors. Effects of doping density of p-GaN layer on the photoresponse have been investigated. In order to accurately simulate the device performance, the theoretical calculation includes doping-dependent mobility degradation by Arora model and high field saturation model. Theoretical modeling shows that the doping density of p- GaN layer can significantly affect the photoresponse of GaN based p-i-n UV photodetectors, especially at schottky contact. We have to make a suitable choice of the doping in the device design according to the simulation results.
Currently, various types of III nitride-based materials have been successfully used for short-wavelength optoelectronic devices. The GaN ultraviolet detector has been wildly used for UV-Index(UVI) monitoring, UV curing and water disinfection. The global solar UVI describes the levels of solar UV radiation at the Earth’s surface. The higher the UVI value, the greater the potential damage to the skin and eyes. The UVI monitoring demonstrator board with GaN detector is briefly introduced in this paper.
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