Studying the effect of space radiation induced defects in multijunction solar cell using APSYS simulation software and comparison with the experimental data

Abstract

In this paper, the state-of-the-art triple junction solar cell with three sub cells and two tunnel diodes is modeled using two dimensional (2D) APSYS finite element analysis software tool. The effect of electron radiation at 1 MeV and 10 MeV energies for different fluences are investigated by introducing different trap levels, trap states and trap concentrations in InGaP top and InGaAs middle sub cells. Two different structures are modeled by varying layer thickness of base and emitter of both top and middle sub cells to understand its effect on the electrical parameters and efficiency of the solar cell. The main indicative parameters - trap concentration and carrier lifetime is affected by the radiation resulting in alteration of electrical performance of solar cells. The radiation induced defects cause permanent damage to the solar cell structure and degrades the electrical performance of solar cells until its end of life (EOL). In this work, APSYS software tool is used to model radiation induced traps with different trap concentrations, generated the electrical parameters and compared with the experimental results. The results obtained from simulation are in good agreement with the experimental data. Probable traps, trap concentrations and carrier lifetime for different electron radiation energies and fluences were extracted by simulation, which can prove to be difficult to perform experimentally as only a few methods like deep level trap spectroscopy and deep level optical spectroscopy exist for deep level trap studies. This study can therefore save valuable R&D time and cost..