Thin Solid Films, 190(1990) 129--138 PREPARATION AND CHARACTERIZATION 129 THIN FILM GROWTH OF SILVER SULPHIDE II. STRUCTURE MODELS OF EPITAXIAL CONTACT LAYERS

The change in the structure and the change in orientation of thin films of Ag2S grown on NaC1 substrates, described in detail in the first part of this work, were studied as a function of the film thickness. The structure of the newly found triclinic pseudocubic modification of Ag2S is discussed. Models for the contact layers are given for the three different growth structures. The structure-geometrical analysis of the epitaxial relationships is applied to explain the mechanism of transformations in the Ag2S films. It was found that in the initial growth stage the structure type and film orientation of Ag2S are induced by the substrate structure. Above a nominal film thickness of about 2.0 nm, the epitaxial orientation is determined mainly by the charge distribution and compensation in the interface region.