Deep Level Transient Spectroscopy Analysis of 10 MeV Proton and 1 MeV Electron Irradiation-Induced Defects in p-InGaP and InGaP-based Solar Cells

Abstract

Minority carrier injection annealing under forward-bias conditions is shown to enhance defect annealing in InGaP and to result in the recovery of solar cells properties. Such peculiar recovery of properties affected by radiation damage demonstrates that InGaP-based devices, under minority-carrier injection-mode operation, have superior radiation resistance compared to GaAs and Si. The first example of a recombination-enhanced mechanism in the ternary compound InGaP is also reported. We have performed detailed studies of the stability of the radiation-induced defect H2 in p-InGaP under various biases in order to determine the dependence of the reaction rate on the position of the Fermi level in the absence of minority carrier injection and recombination. Recombination-enhanced defect annealing of H2 causes a reduction of the minority carrier injection annealing activation energy, compared to thermal annealing from 1.69 eV to 0.52 eV. Analysis of the results reveals that the mechanism involved in the minority carrier injection annealing of the defect is the energy release mechanism, in which enhancement is induced by the energy that is released when a minority carrier is trapped at the defect site.