The influence of surface states on open-circuit voltage for Cr, p-type silicon MIS solar cells

MIS diodes having 100-200 Å SiO2insulator thickness have been tested to determine conductance and capacitance variation with frequency and d.c. bias. Surface-state distribution in the energy gap has been calculated for commercial silicon wafers and Tyco silicon. A peak density of 6 × 10¹²-1 × 10¹³states/cm²-eV is located 0.4 to 0.7 eV above the valence band in most samples. Tyco silicon exhibits a higher total surface-state contribution than commercial silicon, which may account for the reduced open-circuit voltage. Thicker oxides appear to move the distribution closer to the valence band to influence the neutral level of surface states.