Surface-state density and surface potential in MIS capacitors by surface photovoltage measurements. I

Abstract

A simple method is described for the measurement of surface-state density and surface potential in a MIS capacitor. It is similar in principle to the low frequency capacitance method in so far as a dc relationship is established between the surface potential and the voltage applied to the gate electrode. This is achieved by measuring the saturation surface photovoltage. The method differs from the low frequency capacitance method in that it measures the surface potential directly, requiring no additive constant. Experimental results are presented which agree well with those obtained by the low frequency capacitance method. The present method is complementary to a second method to be described by Lam and Rhoderick (companion paper) in that the surface-state density measurable by this first method has a lower limit while that by the second method has an upper limit, the two overlapping at the value of the space-charge capacitance.