Non-linear behaviors of dark current slope in P+N GaAs solar cells following proton irradiations

In this paper, the dark current responses of p⁺n GaAs solar cells are measured before and after 2 MeV proton irradiations. The responses indicate that the dark current slope is not only a function of applied forward bias, but changes with proton fluence. The change in the dark current slope behavior can be modeled by Shockley-Reed-Hall (SRH) recombination statistics as a buildup of bulk traps in the space charge region having energies away from the mid-gap level. The model also suggests that the energy of proton-induced bulk traps is a signature of radiation type but not the particle fluence.