The annealing behavior of electron, proton, and alpha particle irradia
ted, epitaxial n(+)p InP solar cells has been characterized using seve
ral techniques. Current-voltage measurements were made under simulated
1 sun, AM0 solar illumination and in the dark. The radiation-induced
defect spectra were monitored using deep level transient spectroscopy
and the base carrier concentration profiles were determined through ca
pacitance-voltage measurements. The irradiated cells were annealed at
temperatures ranging from 300 up to 500 K. Some cells were annealed wh
ile under illumination at short circuit while others were annealed in
the dark. These experiments produced essentially the same results inde
pendent of illumination and independent of the irradiating particle. A
n annealing stage was observed between 400 and 500 K, in which the rad
iation-induced defects labeled H3 and H4 were removed and the carrier
concentration recovered slightly, Concurrently there was a small reduc
tion in the junction recombination current and a slight increase in th
e photovoltaic (PV) output of the cell; however, most of the radiation
-induced defects did not anneal, and the overall PV recovery was very
small. A full analysis of the annealing data is given, and a model for
the radiation response and annealing behavior of the cells is present
ed. The results are compared to those reported previously for irradiat
ed, diffused junction InP solar cells. Although the radiation-induced
degradation mechanisms appear to be essentially the same in the two ee
l types, the recovery of the PV output is found to be quite different.
This difference in cell recovery is explained in terms of the defect
annealing characteristics in the individual cell types. (C) 1996 Ameri
can Institute of Physics.