Modification of HgCdTe–Native Oxide Interface by Annealing

The interface properties of Hg1—xCdxTe (MCT) with native oxide (NO) after annealing at various stages of MIS device (Me–Si3N4–SiO2–NO–MCT (p-type)) fabrication have been investigated. Heat treatments were provided in vacuum and in the atmosphere at temperatures of 100 to 130 °C before and after native oxide formation and after deposition of SiO2 overcoated with Si3N4. The fixed charge value in the oxide varied from —2.5 × 1011 cm—2 to +5 × 1011 cm—2 in dependence on the annealing conditions. At the same time the amount of interface traps and near-surface band-gap states changed. It is assumed that these changes are caused by mercury migration at heating. The vacuum annealing of the oxidized samples before deposition of the dielectric layers significantly improves the MCT–insulator interface properties.