Extrinsic doping of CdxHg1−xTe— A review

Extrinsic doping by elements which are stable to subsequent processing will become increasingly important in future infra-red device structures based on Cd_xHg_1−xTe. This paper reviews the incorporation and activation of dopants in the most widely used bulk and epitaxial growth methods. Stoichiometry at the growth temperature is shown to be the critical factor affecting dopant activation. Various factors, including stoichiometry, can affect the as-grown electrical properties and the importance of determining the type of conduction in the as-grown state, if successful extrinsic doping is to be accomplished, is stressed. Data on dopant segregation behaviour, in growth from liquids, acceptor ionization energies and carrier lifetimes are also presented and their importance is discussed.