Lattice dynamics of cadmium telluride

Abstract

The phonon dispersion relation of CdTe at 300 \ifmmode^\circ\else\textdegree\fi{}K has been measured for the [100], [111], and [110] directions of propagation using neutron inelastic scattering. The CdTe single crystal was grown from the melt with Cd present as $^{114}\mathrm{Cd}$ to reduce the neutron absorption of the specimen. The results have been fitted to a 14-parameter shell model that represents both the neutron data and other measured properties well when the non-neutron data are included in the fit. The present results, along with earlier measurements on $\ensuremath{\alpha}\ensuremath{-}\mathrm{Sn}$ and InSb, complete the isoelectronic sequence $\ensuremath{\alpha}\ensuremath{-}\mathrm{Sn}\ensuremath{\rightarrow}\mathrm{InSb}\ensuremath{\rightarrow}\mathrm{CdTe}$. The systematic trends in the lattice dynamics of this series of semiconductors (which is characterized by increasing band gap and ionicity) are brought out by comparison of frequency distributions calculated from the shell-model fits.