Influence of 1 MeV electron irradiation on the output parameters of silicon heterojunction solar cells

In this study, influence of electron irradiation with an energy 1 MeV on the output photovoltaic parameters of n-type silicon heterojunction solar cells has been investigated. It has been shown that when irradiated with electrons fluence of 5 × 10¹⁴ e/cm², a significant decrease in the quantum efficiency occurs at wavelengths of longer than 600 nm, leading to a decrease in the short-circuit current from 33.1 to 22 mA/cm² and the open-circuit voltage from 0.68 to 0.53 V, and at a fluence of 1 × 10¹⁵ e/cm² down to 18.3 mA/cm² and 0.51 V respectively. Moreover, the surface recombination velocities of ∼500 cm/s at 5 × 10¹⁴ e/cm² and ∼580 cm/s at 1 × 10¹⁵ e/cm² have been calculated from the load current–voltage characteristics, i.e., ∼16 cm/s before irradiation. Based on capacitance–voltage measurements decrease in charge carrier concentration from 10¹⁵ cm⁻³ to 8.15 × 10¹⁴ cm⁻³ in the bulk of a silicon heterojunction solar cells after electron irradiation at different fluences (${\varphi =10}^{15}$ e/cm²), whereas the carrier removal rate of R_c ≈ 0.21 cm⁻¹ were calculated.