Application of CL/EBIC-SEM Techniques for Characterization of Radiation Effects in Multijunction Solar Cells

We report the results of the characterization of irradiated InGaP
₂
/GaAs/Ge multijunction (MJ) solar cells using the cathodoluminescence (CL) imaging/spectroscopy and electron beam induced current (EBIC) modes of scanning electron microscopy (SEM). These techniques were applied to verify the influence of irradiation damage on the optoelectronic properties of each subcell in the monolithic MJ structure and correlate them with the illuminated (AM0, 1 sun, 25°C) current-voltage (
I
-
V
) and quantum efficiency (QE) measurements. Minority carrier lifetime degradation data from CL measurements confirm that the GaAs subcell dominates the overall degradation of the 3J device. Also, a carrier removal mechanism in the GaAs subcell was revealed from the EBIC/CL measurements.