Studying C-V characteristics of MIS structures with ALD Al-=SUB=-2-=/SUB=-O-=SUB=-3-=/SUB=- on n- and p-CdHgTe stabilized with ultra-thin native oxide

Abstract

Capacitance--voltage characteristics of metal dielectric semiconductor structures with atomic layer deposition Al2O3 on n- and p-Cd0.22Hg0.78Te (with and without a surface graded-gap layer) preliminary oxidized in oxygen glow discharge plasma (with the resulting oxide thickness of 2 nm) have been studied. The obtained structures reveal the positive fixed charge with a density of ~(1-6)·1011 cm-2. The ratio between a slow surface states density and a surface band gap width is almost independent on graded-gap layer presence, with the value of ~(4-8)·1011 cm-2·eV-1. The proposed passivation approach provides near-ideal low-frequency capacitance-voltages characterized by weak influence of fast surface states. Films of CdHgTe grown without the graded-gap surface layer are proved to be much more sensitive to the process of oxidation in glow discharge plasma. Keywords: mercury cadmium telluride, film, surface states, plasma.