Degradation mechanisms of InGaP solar cells by irradiation with less than 100 keV electrons

Abstract

InGaP solar cells with high radiation resistivity are not expected to be degraded by irradiation with less than 100 keV electron-beams. Recently, it was observed that the InGaP solar cells were degraded by irradiation with 60 keV electron-beams. However, a mechanism of this degradation is unclear. In this study, we use deep-level transient spectroscopy (DLTS) to investigate a carrier trap levels in InGaPsolar cells irradiated with less than 100 keV electron-beams. The result of DLTS indicates that non-ionizing energy loss (NIEL) may not explain the degradation caused by low-energy electron beams well. Additionally, we propose displacement threshold energy (Ed) of phosphorus in InGaP by calculating introduction rate of irradiation-induce defect.