Minority carrier lifetime in <i>n</i>-type Bridgman grown Hg1−<i>x</i>Cd<i>x</i>Te

Abstract

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.