Modeling and optimization of GaN-based betavoltaic batteries: Comparison of p-n and p-i-n junctions

Nuclear battery is a promising long-life power source. Selecting semiconductors with high limit efficiency and appropriate device structures effectively improves their output performance. In this work, a GaN-based (hexagonal) betavoltaic battery with Ni63 source was simulated by Monte Carlo codes and COMSOL Multiphysics, and the energy converters, including p-n junction and p-i-n junction, were compared and optimized. We analyzed the effects of thickness and doping concentration of each region on the battery performances. The p-region and n-region thickness and doping concentration of the p-n junction-based battery are 0.5, 9.5 mu m, 10(17) cm(-3), and N-d = 10(16) cm(-3), which can achieve 3.77% conversion efficiency, and the short-circuit current density, open-circuit voltage, and maximum output power density are 0.074 mu A/cm(2), 2.01 V, and 0.125 mu W/cm(2), respectively. For the p-i-n junction-based battery, when the thickness and the doping concentration of p-region, i-region, and n-region are 0.5, 3, 6.5 mu m, 10(17), 10(14), and 10(16) cm(-3), respectively, the conversion efficiency, short-circuit current density, open-circuit voltage, and maximum output power density are 5.03%, 0.099 mu A/cm(2), 2.0 V, and 0.167 mu W/cm(2), respectively. By comparing the output parameters of the two types of batteries, the results indicate that the p-i-n junction has a wider depletion region and better output performance compared with the p-n junction. (C) 2022 Author(s).