IMPROVEMENT OF INTERFACE PROPERTIES IN MU-C-SIC POLY-SI/MU-C-SI DOUBLE-HETEROJUNCTION SOLAR-CELL/

A new type of double heterojunction thin film solar cell has been deve loped with a p mu c-SiC/n poly-Si/n mu c-Si/Al structure. By efficient ly employing the wide band gap window effect and the back surface held (BSF) effect with hydrogen passivation treatment, a fill factor highe r than 80% has been obtained with a conversion efficiency of 17.2%. In order to determine the detailed mechanism of the enhancement of cell performance, a systematic measurement of the rear interface recombinat ion velocity has been performed using poly-Si based solar cells with t he p mu c-SiC/a-SiC/n poly-Si/n mu c-Si/Al structure. It is found that the interface recombination velocity decreases by more than one order of magnitude with the insertion of the n mu c-Si rear side layer. Pos sible mechanisms for the improvement of cell performance are discussed on the basis of a series of characterizations of the devices with sev eral different interface layers.