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

Abstract

Combined with the actual parameters of silicon carbide (SiC), an accurate numerical model is established to predict the energy conversion efficiency ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\eta _{c}$ </tex-math></inline-formula> ) of the semiconductor conversion device in Ti <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{{3}}\text{H}_{{2}} \vphantom {^{\int }}$ </tex-math></inline-formula> 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 ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${L}_{n}$ </tex-math></inline-formula> ) and surface recombination velocity ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${S}$ </tex-math></inline-formula> ) of p-type region, that is, under different material qualities represented by <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${S}$ </tex-math></inline-formula> and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${L}_{n}$ </tex-math></inline-formula> , compared with the conventional p-i-n diode (Cov. p-i-n), <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\eta _{c}$ </tex-math></inline-formula> of TP p-i-n increases by a maximum of 110.7% and 13.3% for Ti <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{{3}}\text{H}_{{2}}$ </tex-math></inline-formula> 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 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${S}$ </tex-math></inline-formula> and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${L}_{n}$ </tex-math></inline-formula> deteriorates, the maximum reduction in <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\eta _{c}$ </tex-math></inline-formula> for Cov. p-i-n is 10.9%, while the maximum reduction in <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\eta _{c}$ </tex-math></inline-formula> for TP p-i-n and PLSF p-i-n is only 2.8% and 0.3%, respectively.