High efficiency isothermal LPE grown GaAs solar cells with high fill factor

GaAs solar cell with Ga sub 0.1 Al sub 0.9 As window layers were produced by isothermal liquid phase epitaxy (LPE). The p-doped emitter was directly diffused into the n-substrate without an intermediate buffer layer. In spite of this simple structure of the cells a high fill factor of 85 percent and a high open voltage of 1.01 V could be achieved which resulted in high efficiencies of 19 to 20.6 percent for 1 x 1 square centimeter cells. The homogeneity of the epitaxial layers and of the antireflection coating could be monitored by mapping techniques. The cell parameters were determined by 1 sun AM 1.5 simulator and dark current measurements.