Effects of fixed charges in the oxide of thermally oxidised m.i.s. solar cells

The open-circuit voltage Vo.c of m.i.s. cells has been reported and has been observed from our own experiments to be in the range of 400¿¿525 mV for Al-SiO2-p-Si cells and in the range of 220¿¿400 mV for Au-SiO2-n-Si cells. This is in contrast to the reported values of barrier heights for schottky diodes without an insulating layer. The difference in Voc is due to the change in the effective barrier height ¿¿mS. The change in ¿¿mS is assumed to be due to fixed positive charges in the thin oxide, and from the reported values of ¿¿mS the charge density in the oxide Qss/q has been calculated to be about 5 ¿¿ 1012 cm¿¿2.