Assessment of interface state density in silicon metal-oxide-semiconductor transistors at room, liquid-nitrogen, and liquid-helium temperatures

The interface state density of silicon metal-oxide-semiconductor (MOS) transistors operated at room, liquid-nitrogen, and liquid-helium temperatures is investigated using the conventional subthreshold slope technique. The magnitude of the interface state density found of the order of 1013–1014/eV cm2 at liquid-helium temperature, suggests that such states correspond to the localized states situated in the band tails below the mobility edge of the two-dimensional subband. Moreover, the interface state densities found by the subthreshold slope have been confirmed using the dynamic transconductance technique.