THEORY FOR ELECTRON AND HOLE TRANSPORT IN HGTE-CDTE SUPERLATTICES

We present results of the first detailed theory for electron and hole transport in HgTe-CdTe superlattices. The calculation incorporates the superlattice band structure in full generality, and also treats multi-well scattering and screening processes which have been ignored in previous theories. It is predicted that whereas the electron and hole should be nearly equal at low temperatures, the hole mobility falls far below the electron value at somewhat higher temperatures due to the extreme nonparabolicity of the valence band. This prediction is entirely consistent with experimental results reported previously. Excellent quantitative agreement with the data over a broad temperature range is achieved if interface roughness scattering is considered in addition to ionized impurity scattering, acoustic and optical phonon scattering, and electron-hole scattering. It is pointed out that low-temperature electron mobilities for a number of thin-well HgTe-CdTe superlattices follow the d(w)6 dependence expected for the interface roughness mechanism.