A theoretical analysis and computer simulation of the growth of epitaxial films

Equations are derived which describe the growth of epitaxial islands on a crystalline substrate subject to certain restrictions, and an attempt is made to define the limits of their application in a physical system. For an initial random distribution of point nuclei, the growth of islands which instantaneously coalesce to a fixed shape obeys equations of the form : In ( N / N 0 ) = -2 N ⅓ 0 A V -⅔ T ⅔ for N 0 > N > 10 -2 N 0 and P = P 0 (1- N / N 0 ) for all N , where 0.5 < P 0 < 0.6. In these equations the island distribution is described in terms of three parameters: the island density N , the fractional surface coverage P and the mean thickness T . The constants A and V are fixed by the shape of an island of size r , such that the volume is Vr 3 and the interface area is Ar 2 .

Soft Matter ◽  
2019 ◽  
Vol 15 (43) ◽  
pp. 8800-8807 ◽  
Author(s):  
Morgan Reik ◽  
Melanie Calabro ◽  
Sean Griesemer ◽  
Edward Barry ◽  
Wei Bu ◽  
...  

This study examines the way in which fractional surface coverage on a nanoparticle surface affects nanoparticle interactions and the long-range order of Langmuir monolayers.


2004 ◽  
Vol 151 (5) ◽  
pp. G368 ◽  
Author(s):  
Wonseop Choi ◽  
Seung-Mahn Lee ◽  
Jeremiah Abiade ◽  
Rajiv K. Singh

2002 ◽  
pp. 337-378 ◽  
Author(s):  
Jozef Telega ◽  
Wlodzimierz Bielski

The aim of this contribution is mainly twofold. First, the stochastic two-scale convergence in the mean developed by Bourgeat et al. [13] is used to derive the macroscopic models of: (i) diffusion in random porous medium, (ii) nonstationary flow of Stokesian fluid through random linear elastic porous medium. Second, the multi-scale convergence method developed by Allaire and Briane [7] for the case of several microperiodic scales is extended to random distribution of heterogeneities characterized by separated scales (stochastic reiterated homogenization). .


2020 ◽  
Vol 30 (1) ◽  
pp. 109-119
Author(s):  
Aleksandar Lebl ◽  
Dragan Mitic ◽  
Zarko Markov ◽  
Verica Vasiljevic

The output power of traffic channels in one cell of GSM like systems is estimated in this paper. We consider the real case: the number of users is much higher than the number of channels, the output power of one channel depends on the cube of the distance between a mobile user and the base station, and the distribution of users in the cell is uniform. We derive the expressions for cumulative distribution of output power of one channel and for the mean output power of the whole base station. Results of the calculation are confirmed by computer simulation.


1972 ◽  
Vol 11 (63) ◽  
pp. 451-454
Author(s):  
David P. Adam

AbstractThis paper elaborates on the note by Andrews and others (1971). It demonstrates that one may obtain any arbitrary value of r between two series of observations by adjusting the mean values of the two series before cumulating them. A computer simulation is used to illustrate the behavior of random Normal series cumulated under varying conditions.


2010 ◽  
Vol 150-151 ◽  
pp. 1358-1363
Author(s):  
Bin Fang ◽  
Chuan Zhen Huang ◽  
Chong Hai Xu ◽  
Sheng Sun

The fabrication is a key process for the preparation of ceramic tool materials, which governs the mechanical properties of ceramic tool materials under the condition of the same compositions. A computer simulation coupled with fabrication temperature for the hot-pressing process of single-phase ceramic tool materials has been developed using a two-dimensional hexagon lattice model mapped from the realistic microstructure without considering the presence of pores. The fabrication of single-phase Al2O3 is simulated. The mean grain size of simulated microstructure by Monte Carlo Potts model integrated with fabrication temperature increases with an increase in fabrication temperature, which is consistent with the experiment results.


1992 ◽  
Vol 278 ◽  
Author(s):  
V. E. Fradkov ◽  
M. E. Glicksman ◽  
J. Nordberg ◽  
M. Palmer ◽  
K. Rajan

AbstractGrain growth in polycrystals occurs by decreasing the total number of grains as a result of the disappearance of small ones. That is why the both the kinetic and topological details of shrinking of small grains are important.In 2-D, “uniform boundary model” assumptions imply the von Neumann-Mullins law, and all grains having less than 6 neighbors tend to shrink. The mean topological class ef vanishing grains was found experimentally to be about 4.3. This result suggests that most vanishing grains are either 4- or 5-sided, not transforming to 3-sided ones.Shrinking of 4- and 5-sided 2-D grains was studied experimentally on transparent, pure SCN, (succinonitrile) polycrystalline films and by direct computer simulation of grain boundary capillary motion together with triple junctions. It was found that the grains which are much smaller than their neighbors are topologically stable.


2012 ◽  
Vol 599 ◽  
pp. 202-205
Author(s):  
Hui Xin Tai ◽  
Yu Lan Yang ◽  
Fuying Liu

This paper aims to investigate how the wind drection influence the outdoor wind environment. Fluent Airpak is used to simulate the wind environment of a residential area in Hangzhou city of China, the atmosphere boundary layer (ABL) is setted up as 16 wind direction with the mean velocity on each wind direction throughout the local typical year meteorological data. The simulation yield the data for the Maximum Wind Velocity (MWV) and the Amplification Factor (AF) Two main findings are:1)The MWV and AF vary greatly according to the wind direction setted up in ABL. 2)None of the wind directions which present to the maximum MWV and the maximum AF in the residential area is consistent with the wind direction with highest frequency in the local typical year meteorological data. Therefore, it is suggested that the outdoor wind simulation should be carried out by the all directions rather than the wind direction with the highest frequency.


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