Орієнтаційні особливості нанокристалів у парофазнихконденсатах PbTe-Bi2Te3

Abstract

By methods of atomic-force microscopy and computer simulations we investigated the effects of orientation and crystallographic form of nanocrystals in vapor-phase condensates of solid solutions PbTe-Bi2Te3, grown for fresh cleavages (0001) of mica-muscovite by open evaporation in a vacuum at various deposition time (τ = 15–75 s) and the optimal temperature evaporation Tv = 970 K and deposition Ts = 470 K. We researched the obtained samples with atomic force microscope (AFM) “Nanoscope 3a Dimension 3000” (“Digital Instruments”, USA) in the periodic contact mode. Measuring was conducted in the central portion of samples using serial silicon probes NSG-11 with a nominal tip radius of up to 10 nm. The research confirmed the implementation of nucleation processes, aggregation and coalescence of individual pyramidal nanostructures by Volmer–Weber mechanism. For the first time based on the analysis of averaged azimuth angles of nanocrystals by discrete transformation methods and the use of the autocorrelation function we determined the dominance of figures, symmetrical to axes of the 6-th and 3-rd order which in most cases are coordinated between themselves and are always coordinated with the figures that have symmetry of the 4-th order. On the basis of normal distributions for averaged radial angles of nanocrystals for the first time we defined the correlation of steep and gently sloping crystallographic forms of cubic system nanocrystals, their orientation and mutual consistency. We found out the prevalence of planes {110}, {123}, where their relative contribution depends on the time of deposition of the pair on the substrate (thickness of condensates).