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 Ti $^{{3}}\text{H}_{{2}} \vphantom {^{\int }}$ and 63Ni 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 show that, under different minority carrier diffusion length ( ${L}_{n}$ ) and surface recombination velocity ( ${S}$ ) of p-type region, that is, under different material qualities represented by ${S}$ and ${L}_{n}$ , 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 Ti $^{{3}}\text{H}_{{2}}$ and 63Ni, 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 ${L}_{n}$ 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.