Gettered GaP Substrates for Improved Multijunction Solar Cell Devices
Date of this Version6-2011
Montgomery, K.H., Allen, C.R., Wildeson, I.H. et al. Journal of Elec Materi (2011) 40: 1457. doi:10.1007/s11664-011-1605-1
We report on the characterization of gettered p-type GaP substrates for application in high-efficiency multijunction solar cells. A commercial zinc-doped GaP substrate was divided, with one piece soaked in a phosphorus-saturated gallium-aluminum melt at 975A degrees C. Low-temperature continuous-wave photoluminescence indicated a significant decrease in deep-level impurity peaks due to oxygen and zinc-oxygen complexes after gettering in the phosphorus-saturated gallium-aluminum melt. To illustrate what effect this has on minority-carrier diffusion lengths, Au/GaP Schottky solar cells were fabricated on the substrates, and the spectral response of each was examined. A marked increase in response across all wavelengths on the gettered sample indicates an increase in minority-carrier diffusion lengths. To ensure these results were not simply due to an increase in the depletion region width resulting from a change in carrier density, C-V profiling was performed and found only a small change in carrier concentration of the gettered sample.
Nanoscience and Nanotechnology