Electron transport in theHg1−xCdxSealloy system

An experimental and theoretical study of the electron mobility in the semimetal-semiconductor alloy system ${\mathrm{Hg}}_{1-x}{\mathrm{Cd}}_x\mathrm{Se}$ is reported for the range of compositions $0.12\le x\le 0.68$ and at temperatures from 4.2 to 300 K. The samples used in the study are single-crystal specimens grown by the traveling-molten-zone and the Bridgman methods. The mobility data are analyzed in terms of a microscopic theory of electrical conduction appropriate to the alloy system, and the dominant intrinsic and defect-scattering mechanisms are determined. The analysis includes scattering of electrons by longitudinal-optical phonons, longitudinal- and transverse-acoustical phonons, charged and neutral defects, heavy holes, and the compositional disorder potential of the alloy. It is found that longitudinal-optical-phonon scattering is the dominant mechanism at room temperature for all alloys in the composition range studied. Acoustical-phonon scattering is unimportant at all temperatures and compositions. Scattering associated with the compositional disorder of the alloy increases from 5% of the total scattering at $x=0.12\mathrm{} \mathrm{to} 21\%$ at $x=0.68\mathrm{}$. Evidence is presented for the presence of four defect species: a donor associated with the HgSe lattice, a donor associated with the CdSe lattice, an acceptor associated with the CdSe lattice, and a stable neutral defect associated with the HgSe lattice.