Back surface fields for n/p and p/n GaInP solar cells

The authors have grown n/p/p/sup +/ and p/n/n/sup +/ GaInP/sub 2/ top cells, lattice matched to GaAs for multijunction tandem solar cells. They have studied the effect of different types of back surface field (BSF) layers on the cell parameters of each cell. These layers are namely, abrupt strained GaInP/sub 2/, graded strained GaInP/sub 2/, disordered GaInP/sub 2/ and AlGaAs layers. The measurements were done under 1-sun AMO spectrum. The results show that the abrupt strained GaInP/sub 2/, BSF outperforms the disordered GaInP/sub 2/ BSF. Likely related to material quality, the AlGaAs layer clearly produce the least efficient BSF. It has been found that the abrupt strained Ga/sub x/In/sub 1-x/P BSF with x=0.56 gives better results than the case with x=0.63 for the p/n/n/sup +/ structure.