Optimization of the parameters of power sources excited by $\beta$-radiation

The experimental results and calculations of the efficiency of the energy conversion of Ni-63 $\beta$-radiation sources to electricity using silicon $p$–$i$–$n$ diodes are presented. All calculations are performed taking into account the energy distribution of $\beta$-electrons. An expression for the converter open-circuit voltage is derived taking into account the distribution of high-energy electrons in the space-charge region of the $p$–$i$–$n$ diode. Ways of optimizing the converter parameters by improving the technology of diodes and optimizing the emitter active layer and $i$-region thicknesses of the semiconductor converter are shown. The distribution of the conversion losses to the source and radiation detector and the losses to high-energy electron entry into the semiconductor is calculated. Experimental values of the conversion efficiency of 0.4–0.7% are in good agreement with the calculated parameters.