Molecular Dynamics Simulations On The Crystal Growth Of Carborundum

Due to the wide band gap, high thermal conductivity and large electron saturation drift rate in electrical properties, Silicon carbide is showing great potential and broad market prospects. And it becomes a hot research in recent years. Taking the Silicon carbide as research object, this paper compared the difference of the MEAM potential and the Tersoff potential on the melting and solidifications by molecular dynamics firstly. And then, the effects of the temperatures, carbon concentrations and growth planes on the crystal growth of Silicon carbide are simulated with the better potential. The result shows:(1) The melting process of Silicon carbide with MEAM potential is similar as that with Tersoff potential. The difference is the melting points. With MEAM potential, the bulk melting point is 4250K, and the thermodynamic melting point is 3338K; With Tersoff potential, the bulk melting point is 4750K, and the thermodynamic melting point is 3430K. The melting point for the MEAM potential is closer to the physical experimental result. However, they are different on the crystal growth of Silicon carbide distinctly. The Silicon carbide with tersoff potential can't grow up when the under cooling temperature range from 0K-1000K, while it can with the MEAM potential. And the crystal grows fastest at the undercooling of 400K.(2) The crystal growths of Silicon carbide at different temperatures have been carried out with the MEAM potential. It has been found that:when the temperatures are within the range of 2100-3300K, the crystal growth rates of Silicon carbide increase first, and then decrease with the temperature increasing. The crystal growth rate reaches the maximum at 2900K. The crystal can't grow up normally under the temperature of 2100 K (for example,1700K). And it melts above the temperature of 3300 K (for example,3400K). The relationship between temperature and the crystal growth rate of silicon carbide has been analyzed theoretically.(3) The crystal growths of Silicon carbide with different carbon atomic concentrations at 2900K have been performed. It has been found that:when the carbon atomic concentrations are less than 45%, the crystal growth rates of Silicon carbide increase with the increasing of carbon concentrations. After the 45%, the growth rates will drop down. And the silicon carbide can't grow up when the carbon concentrations are less than 1%.(4) The crystal growths of Silicon carbide with different growth planes at 2900K have been performed. It has been found that:The crystal of Silicon carbide can grow up normally when the growth planes are (100) or (111) planes. And the crystal growth rate of (100) planes is slightly faster than that of (111) planes. In the small simulation systems, the crystal growth of Silicon carbide with the (110) planes as the growth plane can't be observed.