167 research outputs found
Generalized Muller-Kern formula for equilibrium thickness of a wetting layer with respect to the dependence of the surface energy of island facets on the thickness of the 2D layer
Experimental results indicate a particular importance of such a value as the equilibrium thickness of the wetting layer during epitaxial growth according to the StranskiβKrastanow mechanism in systems with a lattice mismatch. In this paper the change in free energy during the transition of atoms from the wetting layer to the island in such systems is considered. Recent experimental results also show that the surface energy of the island's facets depends upon the thickness of the deposited material. So, in this paper the equilibrium thickness of the wetting layer, at which transition from 2D to 3D growth becomes energetically favorable, is calculated with the assumption that the specific energy of the island's facets depends upon the wetting layer thickness. In this approximation a new generalized MullerβKern formula is obtained. As an illustration of the proposed method, an example of a numerical calculation according to the new formula for the material system of germanium on a silicon (001) surface is given. The result for the found equilibrium thickness of the wetting layer is rather unexpected since it differs from the value obtained in the bounds of the traditional MullerβKern model
DETERMINATION OF TYRES FLEXIBILITY TO MOVE ALONG DEFORMED SOILS
Simple and objective index is proposed to estimate preliminarily correspondance of various tyres parameters and their ability to move along deformed soils as well as to choose tyres under working load
The surface roughening of GaN by wet chemical etching
Enhancing the light extraction efficiency is an important problem in the manufacturing of GaN-based LEDs. Many methods have been carried out to increase the external efficiency, including roughening the surface of the LED. In this study, we proposed an approach of wet chemical etching in KOH and K2S2O8 mixed solutions for roughening the surface of GaN. An analysis on change the surface of GaN is described as a function of etching time
Analysis of the 7x7 to 5x5 superstructure transition by RHEED in the synthesis of Ge on Si (111) in an MBE installation
In this paper, we consider the 7x7 to 5x5 superstructure transition during the synthesis of Ge epitaxial layers on a Si (111) surface in its temperature range from 250 to 700 Β°C. This transition is investigated by reflection high-energy electron diffraction (RHEED). As a result, the dependences of the critical thickness of the 7x7 to 5x5 superstructure transition on the substrate temperature are obtained for the first time
Kinetics of epitaxial formation of nanostructures by Frank-van der Merwe, Volmer-Weber and Stranski-Krastanow growth modes
Nowadays, two-dimensional crystals (2D materials) and structures with quantum dots (0D materials) are considere
Measurement of the charge carrier mobility in MEH-PPV and MEH-PPV-POSS organic semiconductor films
Controlling of Ge quantum dots arrays parameters in Ge/Si nanoheterostructures grown by molecular beam epitaxy method
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