The Optimal Choice of Semiconductor Converter to Increase Power and Efficiency in Betavoltaic Batteries with 3H, 63Ni, and 147Pm Beta Sources

Semiconductor materials play an important role as transmitters of electrical energy in betavoltaic batteries. Optimal selection will increase the efficiency of these batteries. In this study, based on common semiconductors and relying on increasing the maximum efficiency of betavoltaic batteries and the possibility of using 3H, 63Ni, and 147Pm beta sources, the indicators and criteria for optimal selection of semiconductor materials were determined. Evaluation criteria include backscattering coefficient of beta particles from semiconductors, efficiency of electron-hole pairs generation, electronic specifications and properties, radiation damage threshold, radiation yield, stopping power and penetration of beta particles in semiconductors, physical characteristics, and temperature tolerance, accessibility, and fabrication were considered. Based on these criteria and compared with silicon semiconductors, conventional semiconductors have been quantitatively evaluated. Ten semiconductors including β-B, Diamond, 2H-SiC, 3C-SiC, 4H-SiC, 6H-SiC, c-BN, AlN, MgO, B4C with effective atomic number less than 14 and bandgap above 1.12 eV at room temperature (300K) compared to silicon semiconductors were evaluated. Considering the results of evaluation indicators, Diamond, c-BN, and 4H-SiC were selected as more suitable semiconductors in terms of efficiency. Based on the experiments performed in this study, a betavoltaic semiconductor type junction for Schottky diamond with 147pm radioisotope, for 4H-SiC semiconductors with 63Ni or 3H radioisotopes, and for three-dimensional structures of betavoltaic batteries, Si combination with 147pm or 63Ni radioisotopes is recommended for planar batteries.