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

The open-circuit voltage V o.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-SiO 2 -p-Si cells and in the range of 220-400 mV for Au-SiO 2 -n-Si cells. This is in contrast to the reported values of barrier heights for schottky diodes without an insulating layer. The difference in V oc is due to the change in the effective barrier height o mS . The change in o 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 Q ss/q has been calculated to be about 5 × 10 12 cm -2 .