Effect of oxide tunneling on the measurement of MOS interface states

In principle, capacitance-voltage (C-V) and charge pumping techniques should supply the same information on the energy distribution of interface states. On the other hand, we have found from measurements taken on the same samples that the C-V method systematically gives a lower state density in the midgap region, with a steeper energy dependence. We show that the agreement is greatly improved by introducing in both extraction techniques the effects of carrier tunneling in slow oxide traps.