Two-dimensional electron systems in inversion layers of p-type Hg0.8Zn0.2Te metal-insulator-semiconductor structures

Strong oscillations on capacitance and conductance have been observed in p-type Hg0.8Zn0.2Te metal-insulator-semiconductor structures, made by using a recent process for the interface passivation. This behaviour is attributed to a two-dimensional electron gas in the n-inversion layer and the variation of the conductance maximums with temperature indicates that the dominant perpendicular transport mechanism for electrons is an incoherent two-step tunnelling through deep levels in the gap. Three models have been used to describe the quantum confinement: the simple variational method, the triangular potential approximation and the propagation matrix method. The later approach takes into account the non parabolicity of the conduction band structure and uses a finite height barrier at the insulator-semiconductor interface. A very good agreement between experimental and calculated values for the two lowest subband energy is obtained.