Deep-level defects introduced by 1 MeV electron radiation in AlInGaP for multijunction space solar cells

Presented in this paper are 1 MeV electron irradiation effects on wide-band-gap (1.97 eV) (Al0.08 Ga0.92) 0.52 In0.48 P diodes and solar cells. The carrier removal rate estimated in p -AlInGaP with electron fluence is about 1 cm-1, which is lower than that in InP and GaAs. From high-temperature deep-level transient spectroscopy measurements, a deep-level defect center such as majority-carrier (hole) trap H2 (E _ν +0.90±0.05 eV) was observed. The changes in carrier concentrations (Δp) and trap densities as a function of electron fluence were compared, and as a result the total introduction rate, 0.39 cm-1, of majority-carrier trap centers (H1 and H2) is different from the carrier removal rate, 1 cm-1, in p -AlInGaP. From the minority-carrier injection annealing (100 mA cm2), the annealing activation energy of H2 defect is ΔE=0.60 eV, which is likely to be associated with a vacancy-phosphorus Frenkel pair (Vp - Pi). The recovery of defect concentration and carrier concentration in the irradiated p -AlInGaP by injection relates that a deep-level defect H2 acts as a recombination center as well as compensator center.