An n-SIPOS: p-SIPOS homojunction and a SIPOS-Si-SIPOS double heterostructure

For maximal performance, solar cells should resemble semiconductor lasers; i.e. they should be constructed in the form of a double heterostructure. This configuration is also sometimes called ''minority carrier mirrors''. We have found rather good performance in SIPOS-crystalline silicon-SIPOS double heterostructures as well as in a p-n homojunction made entirely of SIPOS. This sheds some light on the truly outstanding performance of the n/sup +/-SIPOS: Si heterojunction which has a J /sub o/ = 10/sup -14/ Amps/cm/sup 2/. It has been recognized for some time that the structure of an ideal solar cell should resemble that of a semiconductor laser. The solar cell should be built in the form of a double heterostructure. In this configuration, a narrow bandgap active layer is sandwiched between two wide bandgap layers of opposite doping. The wide bandgap materials may be called ''minority carrier mirrors'' although this term is more frequently applied to high-low homojunctions at the rear of solar cells.