Structure of p-Bi₂Te₃ thin films prepared by single source thermal evaporation in vacuum

Abstract

The growth mechanism, microstructure, and crystal structure of thin Bi₂Te₃ films with thicknesses d = 28 - 620 nm prepared by thermal evaporation of stoichiometric Bi₂Te₃ crystals in vacuum onto glass substrates were studied using X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, and atomic force microscopy. The obtained thin films were polycrystalline, exhibited p-type conductivity and did not contain any other phases except for Bi₂Te₃. It was shown that with increasing film thickness, the crystallite size increased up to ~ 700-800 nm. It was established that the preferential orientation of crystallite growth was [00l] direction corresponding to a trigonal axis С3 in hexagonal lattice. When the film thickness exceeded ~ 200-250 nm, along with reflections from (00l) planes, reflections from other planes appeared, which indicated a certain disorientation of crystallites. The results obtained show that using a simple and inexpensive method of thermal evaporation from a single source and choosing optimal technological parameters, one can grow thin p-Bi₂Te₃ films of sufficiently high quality.