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

The authors consider the capacitance-voltage relation for a metal-insulator-semiconductor structure on p-type Hg 0.8 Cd 0.2 Te to show how the quantisation of the surface carriers changes the conditions for band bending. The existence of a distinct ground state, with energy E 0 comparable to the gap E g , delays the onset of inversion until the bending exceeds E g +E 0 . 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.