A comparison of majority- and minority-carrier silicon MIS solar cells

A systematic experimental investigation is reported of metal-SiO 2 -silicon (MIS) solar cells, as a function of SiO 2 thickness d , in the useful range 8 Å < d < 20 Å. Both majority-carder (Au-SiO 2 - nSi) and minority-carrier (Al-SiO 2 -pSi) structures are studied and their performance compared for SiO 2 layers prepared under identical oxidation conditions and with identical silicon surface treatments. The short-circuit current densities are observed to be suppressed by tunneling through the SiO 2 layers for d \gsim 17 Å, whereas fill factors begin to decrease at even smaller values of d. The optimum effective AM1 conversion efficiencies for the majority-carrier cells are 9-10 percent for 10 Å ≲ d ≲ 14 Å, and for the minority-carrier cells are 11-12 percent for d \simeq 10-11 Å. These results are in agreement with theoretical calculations, also presented here, which take account of both electrostatic and dynamic effects of interface states, and of their dependence on bias voltage and illumination.