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Molecular Dynamics Simulations on the Crystal Growth of Carborundum

Author: HongTao
Tutor: ZhouNaiGen
School: Nanchang University
Course: Materials Physics and Chemistry
Keywords: Silicon carbide Crystal growth MEAM potential function Molecular dynamics simulations
CLC: O781
Type: Master's thesis
Year: 2011
Downloads: 109
Quote: 0
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Abstract


Silicon carbide has a wide band gap, high thermal conductivity, saturated electron drift velocity and excellent electrical properties, is showing great potential for development and broad market prospects, so in recent years, the study of silicon carbide is very popular. The silicon carbide, the use of the method of molecular dynamics simulations, the first comparative study of the similarities and differences in the process of melting and crystal growth of silicon carbide MEAM potential and Tersoff potential described selected potential function is more suitable for the growth of silicon carbide crystals. Then use the potential function to simulate the different temperatures, different carbon concentrations and different growth face of SiC single crystal growth, results showed: (1) MEAM potential and Tersoff potential described melting process of silicon carbide is basically the same, different both melting point: MEAM potential melting point of 4250 K, and the thermodynamic melting point: 3338 K; the Tersoff potentials body melting point of 4750 K, the thermodynamic melting point of 3430 K. The MEAM potential melting point and physical experiment results closer. Two potential function of the silicon carbide described in a great difference in the crystal growth Tersoff potential Description of the SiC in the undercooling is within the range of 0 K-1000 K can not grow, while the MEAM under the action of the SiC crystals in certain undercooling degree of growth, and undercooling of about 400 K, the crystal growth rate is the fastest. (2) using the MEAM potential functions under different temperature conditions of silicon carbide crystal growth simulation found: SiC crystal growth rate in the temperature range of 2100-3300K, first gradually increases with increasing temperature, to a temperature of 2900K. , the growth rate of the silicon carbide crystal reaches a maximum, and thereafter, the growth rate of the silicon carbide crystal is gradually reduced with increasing temperature. Lower than 2100K (1700K), silicon carbide crystals can not be normal growing up, higher than 3300K (3400K), silicon carbide crystals melting phenomenon. From the theoretical relationship between the temperature and the silicon carbide crystal growth rate to be analyzed. (3) the MEAM potential function, SiC crystal growth simulation under the conditions of the 2900K temperature and concentration of the different carbon atoms: carbon concentration less than 45% when, with the increase of the carbon concentration, the growth rate is faster. When the carbon concentration is as low as 1%, the silicon carbide crystal basically can not grow; while when the carbon concentration exceeds 45%, the growth rate will begin to decrease. (4) using the MEAM potential function, the growth surface, respectively (100), (111) and (110) crystal face of the SiC crystal growth process simulation found: 2900K temperature, (100) and (111) growth plane carbonization The silicon can grow normally slightly higher than the growth rate of the (100) crystal plane of a (111) crystal plane. And (110) crystal plane in our system carbide crystals can not grow, just atomically flat crystal surface will become undulating atomic surface.

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CLC: > Mathematical sciences and chemical > Crystallography > Crystal growth > Theories of crystal growth
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