Design of High-Efficiency SiC Betavoltaic Battery Structures With Reduced Impact of Near-Surface Recombination Based on Accurate Modeling

Combined with the actual parameters of silicon carbide (SiC), an accurate numerical model is established to predict the energy conversion efficiency ( eta c) of the semiconductor conversion device in (TiH2)-H-3 and Ni-63 betavoltaic batteries with an error of less than 1%. Based on accurate simulations, novel p-i-n diodes with thinned p-type region (TP), named TP p-i-n, and with passivation layer surface field (PLSF), named PLSF p-i-n, are proposed as semiconductor conversion devices in this article. The introduction of TP and PLSF reduces the proportion of p- type region with high Shockley- Read-Hall (SHR) recombination and the electron concentration near the surface, thereby reducing SRH and surface recombination loss. The simulation results showthat, under differentminority carrier diffusion length (L-n) and surface recombination velocity (S) of p-type region, that is, under different material qualities represented by S and Ln, compared with the conventional p-i-n diode (Cov. p-i-n), eta c of TP p-i-n increases by a maximum of 110.7% and 13.3% for (TiH2)-H-3 and Ni-63, respectively, and as for PLSF p-i-n are of 134.3% and 15.3%. As a result, when the material quality represented by S and Ln deteriorates, the maximum reduction in eta c for Cov. p-i-n is 10.9%, while the maximum reduction in eta c for TP p-i-n and PLSF p- i-n is only 2.8% and 0.3%, respectively.