US8957306-B2  Chiang et al., &quot;Experimental Results of GaInP2/GaAs/Ge Triple Junction Cell Development for Space Power Systems,&quot; 25th IEEE PVSC, 183-186 (1996).;  Chiang et al., &quot;Large Area GaInP2/GaAs/Ge Multijunction Solar Cells for Space Applications,&quot; 2120-2123(1994).;  Chiang, P.K., et al., &quot;Experimental Results of GaInP2/GaAs/Ge Triple Junction Cell Development for Space Power Systems.&quot; 25th IEEE PVSC. pp. 183-186. May 13-17, 1996. IEEE, Piscataway, NJ.;  Chiang, P.K., et al., &quot;Large Area GaInP2/GaAs/Ge Multijunction Solar Cells for Space Applications.&quot; Conf. Record of the 24th IEEE PVSC. vol. 2, pp. 2120-2123. Dec. 1994. IEEE, Piscataway, NJ.;  Friedman et al., &quot;Back Surface Fields for GaInP2 Solar Cells,&quot; IEEE, 358-360 (1991).;  Friedman, D.J., et al. &quot;Back Surface Fields for GaInP2 Solar Cells.&quot; Conf. Record of the 22nd IEEE PVSC. vol. 1, pp. 358-360. 1991. IEEE, Piscataway, NJ.;  Kurita, H., et al., High Efficiency Monolithic InGaP/GaAs Tandem Solar Cells with Improved Top-Cell Back-Surface-Field Layers. Conf. Proceedings of the 7th International Conf. on Indium Phosphide and Related Materials. pp. 516-519. May 9-13, 1995. IEEE, Piscataway, NJ.;  Sharps, &quot;Growth and Development of GaInAsP for Use in High-Efficiency Solar Cells,&quot; NREL, 1-27 (1994).;  Sharps, P.R., &quot;Growth and Development of GaInAsP for Use in High-Efficiency Solar Cells.&quot; Final Report to the National Renewable Energy Laboratory, pp. 1-27, with appendix. Oct. 1994. NREL, Golden, CO.;  Takamoto et al., &quot;High Efficeincy Monolithic InGaP/GaAs Tandem Solar Cells with Improved Top-Cell Back-Surface-Field Layers,&quot; IEEE (1995).;  Yamaguchi, &quot;Compound Semiconductor Solar Cells, Present Status,&quot; NTT Opto-electronics Labs., 5:143-155 (1990).;  Yamaguchi, M. &quot;Compound Semiconductor Solar Cells, Present Status.&quot; Optoelectronics_Devices and Technologies. vol. 5, No. 2, pp. 143-154. Dec. 1990. NTT Opto-electronics Labs. Tokyo, Japan.