Quantum physics of the surface layer capacitance for narrow-gap HgCdTe

Abstract
The authors consider the capacitance-voltage relation for a metal-insulator-semiconductor structure on p-type Hg0.8Cd0.2Te to show how the quantisation of the surface carriers changes the conditions for band bending. The existence of a distinct ground state, with energy E0 comparable to the gap Eg, delays the onset of inversion until the bending exceeds Eg+E0. The capacitance for inversion shows the effect of both the finite extent of the wavefunction and the small density of states. By fitting to the measured capacitance several quantum parameters of the surface electrons have been determined.