The Monte‐Carlo method is used to simulate the epitaxial growth of semiconductor films with a diamond‐type lattice. Probabilities of isolation, attachment, and diffusion displacements of atoms on the substrate surface are determined for the growth on the (100) and (111) planes. The area of 12 × 12 atoms is chosen for the growth simulation, the periodic regional conditions are preset for excluding boundary effects. The number of the nearest neighbours and the possibility of formation of vacancies are taken into account. The coordinates of atoms are chosen by random numbers, then the possible events are analysed in accordance with the temperature of substrate, supersaturation, diffusion coefficient, and atomic binding energy. The rate of growth, the critical film thickness, and the growth surface roughness are determined. The epitaxial silicon growth occurs faster on the (100) plane but the (111) plane is more smooth. The influence of time, temperature, supersaturation on the film growth rate, and on the film surface roughness is traced. The comparison of computer results with experimental data permits to describe more exactly the mechanism of film growth with allowing for the time of adatom building‐in into a lattice from the position of physical adsorption on the substrate surface.
A simultaneous simulation of the growth process in thc A(K)DP-type anion-doped crystal and growing o f this crystal from aqueous solution under controlled conditions has made it possible t o analyse the mechanism of impurity influence on Ammonium dihydrogen phosphate (ADP)-type crystals produced by the method of temperature decrease and evaporation in a dynamic condition display differences in the morphology for large supersaturations or impurity presence in an aqueous solution. Anisotropy of the growth rate is also observed.A computer simulation of the atom dynamics on the surface makes it possible t o establish the influence of the experimental parameters, such as type and quantity of impurities, supersaturation, temperature, etc. upon the growth process, and thus, upon the crystal morphology, as a whole.The present paper is aimed a t establishing factors responsible for a change in the crystal form, as well as their mechanisms acting in different conditions of the growth with the application of real and computer experimental results.
Experimental resultsThe growth of ammonium dihydrogen phosphate (ADP) and potassium dihydrogen phosphate (KDP) crystals has been made a t temperatures of 30-65 "C from pure solutions of NH4H,P0, and K2H2P0, in the presence of the impurities (NH,),CrO,, (NH,),SO,, (NH4),Mo0, (their concentration being changed from 1 t o 30%).The pure ADP and KDP crystals grew with a normal morphology -having a small coneness of 6-8'. The increase of supersaturationup t o 18% and the crystallisation
The peculiarities of tungsten whisker growth by the diffusion‐dislocation and vapour‐liquid‐solid mechanisms are studied. The model accounts for the basic physical causes of whisker growth in halogen lamps observed in experiments. The simulation by the Monte Carlo technique takes into account local supersaturation fluctuations, caused by certain impurities, their frequency of appearance and their duration. The role of impurities in each of the growth mechanisms is shown and proved by the morphology of whiskers obtained in experiments.
The growth of semiconductor films with a diamond‐type lattice is simulated by the comparison of the probabilities of isolation, creation, and diffusion movements of base and impurity atoms. The Monte‐Carlo method is used to simulate the growth with allowing periodical regional conditions on the boundary of the area. The influence of the supersaturation, deposition temperature on the film growth rate, surface film roughness, critical thickness of continuous films, impurity atom occupation is traced for the silicon film growth. The simulation results are compared with experimental dates on the growth of films and on its doping from vapour phase or molecular beams in vacuum.
The investigation by the Monte-Carlo method of the growth of the silicon epitaxial film at a chloride CVD system has allowed t o find out the composition of adsorption layer, the micromechanism of the reactions of Si atoms building-in into the growing crystalline layer and the growth conditions influence on the growth rate and film surface roughness. The change of adsorptive layer composition in the system SiC1,-HCl-H, (fraction of adaatoms, silicon atoms built-in a crystal and molecules SiCl,) depending on temperature has been determined. The change of silicon film growth rate depending on temperature and concentration change of SiH,CI, has been established and the contribution of growth mechanism (with participation of adatom, silicon atoms and molecules Sic],) into the total rate of film growth has been shown.
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