Analysis of the spectral response of silicon solar cells irradiated with high fluence electrons/protons

An anomalous change in the spectral response of Si space power solar cells induced by high fluence irradiation has been observed. The authors have modeled the spectral response to account for radiation induced changes in the cell structure using the device simulator PC1D. According to the modeled results, the junction depth increases when rapid degradation of the cell occurs, probably due to in-diffusion of phosphorus from the emitter. Also, the weak infra-red spectral response after cell failure has been explained by conduction type conversion of the base layer from p-type to n-type due to the introduction of donor like defects. This conduction type conversion has been confirmed by cross-sectional electron beam induced current (EBIC).