Annealing of radiation damaged gallium arsenide solar cells by laser illumination

Abstract

In this research, preliminary results of a new approach for annealing previously irradiated Gallium Arsenide solar cells is reported. This technique examines the use of laser illumination to induce Forward-Biased current annealing. Five GaAs solar cells were irradiated with 65 MeV electrons at varying fluence levels. Visible laser light produced a 0.5 Alcm 2 forward-biased current density and raised the solar cell temperature by 30' C. Ten to fifteen percent recovery of degraded parameters was achieved in four ofthe five tested cells. The results show that a laser can produce some annealing in radiation damaged GaAs solar cells. Further investigation into the results also indicate that the 65 MeV energy level of the electron irradiation could have caused unrecoverable permanent damage to the solar cells. Follow up research of this annealing technique should be conducted on GaAs cells that are being irradiated at a lower energy level as well as lower fluence level. Repetitive annealing oflightly damaged cells in previous research has provided appreciative recovery using forward bias current techniques. One can expect similar results using the laser induced annealing technique proposed in this research.