3D morphology of II-VI semiconductor nanocrystals grown in inverted micelles

Colloidal CdS nanocrystals have been elaborated by using a technique of the chemistry of colloids. Their mean size range between 3 and 10 nm. The 3D morphology of the nanocrystals has been studied by using high-resolution transmission electron microscopy (HRTEM). The method is based on the measurement of I-g,I-hr(r), the intensity of a family of g lattice fringes as a function of the position r(x,y) in the high-resolution electron micrograph, assuming that I-g,I-hr increases monotonously as a function of the thickness t of the crystal along the electron beam. The range of thickness for the validity of the method has been calculated in the frame of the dynamical theory of electron diffraction. CdS colloids are mainly in the cubic structure of blends-type (B) and a few of them are in the hexagonal structure of wurtzite-type (W). In the cubic structure of B-type, the morphologies are found to be the octahedron and tetrahedron. The hexagonal structure of W-type, have a platelet-like morphology with well-developed basal faces. (C) 1999 Elsevier Science B.V. All rights reserved.