Surface-state studies of nonparabolic band semiconductors using MIS structures

Abstract
Capacitance (CV) and capacitance derivative (C′‐V) measurements have been taken on MIS Hg0.8Cd0.2Te‐ZnS devices. The surface‐state distributions are determined from a digital simulation program describing the characteristics of an MIS structure with a semiconductor having a nonparabolic conduction band and a parabolic valence band. A combination of a nonuniform acceptor surface‐state distribution centered at the conduction band edge and a nonuniform donor surface‐state distribution centered at the valence band edge is necessary to fit the experimental CV and C′‐V data. From flat‐band voltage versus insulator thickness plots, the work function for Hg0.8Cd0.02Te is 4.23±0.67 eV. The immobile trapped charge density in the samples studied has an average value of 1.66×1012 cm−2.

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