Surface potential relaxation in a biased Hg1−xCdxTe metal-insulator-semiconductor capacitor

Biased metal-insulator-semiconductor (MIS) capacitors are known to exhibit a flatband voltage shift which is logarithmic in time. This phenomenon has been attributed to charge exchange between the semiconductor surface and a set of insulator traps distributed either in energy or in depth. It is shown that logarithmic time dependence is also an attribute of a simple capture model which incorporates the relaxation of the semiconductor surface potential which occurs as the density of total trapped charge changes. The predictions of this model are compared with experimental results obtained from a biased MIS structure comprising 600 Å of native oxide on n-type Hg0.70Cd0.30Te.