Étude des propriétés vibrationnelles des interfaces couche mince-substrat par la méthode des fonctions de green

A358 width" but that this capability has little to do with the ability to resolve deviations from surface order. A quantity, "the minimum angle of resolution", is defined to describe the resolving power of a LEED instrument. It depends, in addition to the shape and width of the instrument response function, on the accuracy of the measurement. This concept is applied to a variety of model surfaces with varying degrees of short-range order. It is demonstrated that the size of ordered domain that can be resolved depends on the type of defects present. ComParison is made with the traditional "transfer width" approa.ch.

Surface Science 99 (1980) 714-733 © North-Holland Publishing Company

I~TUDE DES PROPRII~TI~SVIBRATIONNELLES DES INTERFACES COUCHE MINCE-SUBSTRAT PAR LA MI~THODE DES FONCTIONS DE GREEN P. M A S R I

Centre d'Etudes d'Electronique des Solides, Laboratoire Associ~ au CNRS, LA 21, Universitd des Sciences et Techniques du Languedoc, USTL, Place Eugene Bataillon, F-34060 MontpeUier Cddex, France Received 27 February 1980; accepted for publication 12 May 1980

We present a formalism based upon the Green functions method to study the vibrational properties of an interface between two crystals of variable thickness. Analytical expressions are obtained for the surface Green functions where we take into account the force constant variation in the surface plane. Applications are made in the cases of a free surface, stacking fault and film-substrate interface.