ANALYSIS OF HETEROEPITAXIAL ALGAAS SI TANDEM SOLAR-CELL FOR CONCENTRATOR APPLICATIONS/

The development of monolithic AlGaAs/Si tandem sellar cells for concen tration applications is proposed. The theoretical analysis is carried out to express the device parameters as a function of the doping conce ntration and the dislocation density. From the results of this theoret ical analysis, it is demonstrated that when the dislocation density is reduced to below 10(4) cm(-2) photocurrent matching between the top c ell and the bottom cell can be satisfied at the Al composition of AlxG a1-xAsx = 0.21, and the efficiency of the AlGaAs top cell increases ra pidly in the 1 - 100 sun concentration region. In order to achieve ver y high efficiency, the dislocation density must be reduced to below 5 x 10(5) cm(-2) and concentration ratios greater than 100 times must be used.