Homogeneity evaluation of GaAs LPE solar cell processing by photoluminescence mapping and photoluminescence decay measurements
Two-dimensional photoluminescence mapping is used to record the spatial homogeneity of LPE grown Ga sub 0.1 Al sub 0.9 As/GaAs heteroface solar cells on a macroscopic (mm) and on a microscopic (micron) scale. A comparison with LBIC (light beam induced current) images shows a striking correlation in some samples and no correlation in others. These features are discussed in the framework of the minority carrier continuity equation. Photoluminescence decay measurements are performed in the same samples to study the role of surface passivation on minority carrier lifetime. These measurements augment the imaging investigations. The photoluminescence imaging techniques are useful for the assessment of solar cell homogeneity in every step of processing.