Lattice dynamics of Cd‐rich Cd_1−xHg_xTe alloys

Abstract

An investigation is made of the lattice dynamics of low concentration of H g atoms (z < 0.3) in Cd-rich Cdl -zHg,Te mixed system. The vibrational mode frequency for the isolated Hg replacing Cd atoms in CdTe is observed at 131 cm-1. The impurity is described by a perturbation model that accounts for the change of mass a t the impurity site as well as the local variation of nearestneighbour forces. A calculation based on the Green's function theory suggests stiffening in nearestneighbour forces (Af/f = +0.25) due to isolated Hg in CdTe system.On Btudie la dynamique de reseau des alliages Cdl -,Hg,Te du cat6 riche en cadmium (z < 0,3).La frequence du mode vibrationnel du mercure en substitution isolee sur site Cd est trouvde Bgale B 131 cm-l. Ce cas est discute en connexion avec la variation locale des forces introduites par la presence du d6faut. Un calcul bas6 sup une technique de fonctions de Green r6vele que l'introduction d u mercure isole (z = 0) conduit B un net renforcement des forces entre l'impuretd e t ses premiers voisins (Af/f = +0,25).