Gettered GaP Substrates for Improved Multijunction Solar Cell Devices
Kyle H. Montgomery, Charles R. Allen, Isaac H. Wildeson, Jong-Hyeok Jeon, Anant K. Ramdas, Jerry M. Woodall
Journal of Electronic Materials, vol. 40, no. 6, pp. 1457-1460, 2011.
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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 975C. 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.
Gettering, GaP, multijunction solar cell, photoluminescence, spectral response, capacitance–voltage
K. H. Montgomery, C. R. Allen, I. H. Wildeson, J-H. Jeon, A. K. Ramdas, J. M. Woodall, “Gettered GaP Substrates for Improved Multijunction Solar Cell Devices,” Journal of Electronic Materials, vol. 40, no. 6, pp. 1457-1460, 2011.