The Auger-effect in Hg1−xCdxTe

The temperature dependence of the Auger-lifetime of n-Hg_1−xCd_xTe is investigated both theoretically and experimentally for several values of bandgap and of extrinsic carrier-concentration n_ex in the whole range between room and He-temperatures. For semiconducting compounds a pronounced minimum of the lifetime between 10 and 50K and an exponential increase at still lower temperatures are found. The position of the minimum and the exponent depend mainly on the value of the bandgap and on the ratio of the conduction- and valenceband effective masses. Apart from the extended temperature range, which does not allow the use of classical statistics, our calculation differs from earlier work in so far, as we take the band energies and the overlap integrals of conduction- and valenceband Bloch-functions from a k·p-calculation. For semiconducting compounds, we compare the results with those obtained from an estimate of the overlap integrals given by Antončik and Landsberg. Whereas both results are compatible at high temperatures, characteristic differences occur at low temperatures, where we find the lifetime to be proportional to rather than to n_ex⁻². For semimetallic compounds we calculate a weakly temperature dependent Auger-time of the order of 0.1–1 nsec.