ErSi2/Si (111) interface structure determination from lattice imaging

Abstract
This paper is devoted to a detailed analysis of interface structure using high resolution transmission electron microscopy. In the first part the conditions needed to obtain an image similar to the projected potential are established using the dynamical theory of electron diffraction, combined with an analysis of the microscope transfer. In the second part this theory is applied to the ErSi2 structure which is hexagonal and of the AlB2 type. This case is not completely general because the approximation of the very small difference in dynamical amplitude of beams g and -g applies. Thus the contrasts can be predicted. In the third part the ErSi 2/Si interface structure is studied. It is shown how many kinds of contrasts are required to interpret the images. The structures found correspond to two kinds of bonds for silicon atoms located at the interface plane.

Résumé
Dans cet article, une analyse détaillée de la structure de l'interface ErSi2/Si est présentée à partir d'images obtenues en microscopie électronique en transmission haute résolution. Il est montré que dans le cas de ErSi2, bien que ce cristal soit non centrosymétrique, certains contrastes dans l'image peuvent être prévus. L'analyse d'image révèle que deux types de structures cohabitent à l'interface ErSi2/Si, qui correspondent à cet interface à des liaisons de type différent entre atomes de silicium.