Properties of Hg1−xCdxTe native oxide interfaces

The properties of native oxide/semiconductor systems are of obvious importance for all semiconductor technologies in use today. In a few cases, the formation of native oxide/semiconductor interfaces can lead to superior device structures—metal–oxide semiconductor (MOS) devices in Si are a key example. In other cases, the native oxides formed lead to pathological behavior, such as the case for GaAs. The chemical stability of the oxide semiconductor system normally determines its ultimate utility. It is, of course, conceivable that a thermochemically unstable structure may find technological use if the reactions are slow enough. However, the small number of interface defects necessary to affect electrical properties usually dictates that a stable interface is necessary. Hg1−xCdxTe exhibits these types of instabilities through reactions of oxidized Hg and Te with Te bonded Cd. In addition to the above chemical concepts, this paper reviews the kinetics of the oxide Hg1−xCdxTe reactions and the dynamics of subsequently formed electrically active defects (excess Te or Hg). A discussion of the chemical basis for superior properties of sulfides and halogen based passivations will also be presented.