Minority carrier lifetimes have been mapped on slices of n-type Hg1−xCdxTe (x∼0.3) grown by the Bridgman technique. The mean lifetime on a slice has been measured as a function of extrinsic carrier density and composition. Lifetimes at selected positions on slices have been measured as a function of temperature down to 30 K. Aging effects have also been investigated. We show that the lifetime variation with temperature cannot be explained by direct band-to-band recombination alone. The assumption that recombination also occurs via Shockley–Read type recombination centers, situated 10–30 meV below the conduction band edge, enables us to calculate theoretical values of the lifetime in good agreement with the experimental results. Such a model can also be used to explain the variation of lifetime with composition.

CdxHg1−xTe with 0.17<x<0.31 has been annealed using closed-tube and open-tube methods. In both methods the mercury vapor pressure during an anneal was controlled by a mercury reservoir held at a temperature either the same as the CdxHg1−xTe (isothermal anneal), or lower than the CdxHg1−xTe (two-temperature anneal). Isothermal anneals carried out in closed-tube and open-tube systems convert material which is initially p type by native defects to n type. Two-temperature, closed-tube anneals can be used to convert n type to p type, the acceptor concentration being controlled by the CdxHg1−xTe temperature and the mercury vapor pressure. Two-temperature, open-tube anneals also result in conversion from n to p, however, the mercury vapor pressure (over the range studied) does not influence the final acceptor concentration but does affect the time required to reach equilibrium. The results are discussed in terms of the pressure-temperature diagram and the defect/impurity balance in CdxHg1−xTe .

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