High resolution electron microscopic studies of the oxidation process of ZnTe films

Abstract

ZnTe films of about 15 nm thickness were prepared by vacuum deposition from ZnTe power onto NaCl substrates heated to 300°C. Zinc oxide particles with a size of 5 nm which were formed on the surface of ZnTe crystals showed no epitaxial relationship with the latter. Tellurium crystals appeared on certain parts of the ZnTe crystals with specific epitaxial relationships such as $\text{(0}\text{1}\text{1}\text{1}\text{)[10}\text{1}\text{0]}\text{Te}\text{(111)[110]}\text{ZnTe and}\text{(0}\text{1}\text{1}\text{1}\text{)[10}\text{1}\text{0]}\text{Te}\text{(0001)[10}\text{1}\text{0]}\text{ZnTe}$. Oxidation of the (110) surfaces of ZnTe crystals are slower than for any other plane. Images of the (110) films at an initial stage of oxidation contained faint superlattice fringes of about 0.85 nm spacing. On the basis of the matching between the HREM images and computer simulation images, the origin of the fringes was attributed to a periodic array of Zn vacancies introduced by the diffusion of Zn atoms to the surface of the ZnTe crystal.