SiC短程结构的分子动力学模拟

SHORT-RANGE STRUCTURE IN SILICON CARBIDE BY MOLECULAR DYNAMICS SIMULATION

采用Tersoff势函数对晶体、液态、非昌SiC结构进行了分子动力学模拟。模拟的结果表明 :由于C成键的影响使非晶SiC的结构偏离正四面体构型。在晶体中SiC保持长程排列的闪锌矿型结构。液态SiC的模拟得到Si的配位数为 5 64,C的配位数为 3 67,C -C的键角分布在～66°和～ 12 0°有两个峰值 ,表明有相当一部分C是三次配位 ,形成石墨型结构。非晶SiC的结构基本保持了液态SiC的构型 ,但Si和C的配位数下降 ,Si的配位数为 4 2 4 。

Tersoff potential function has been applied to study short-range structures of crystal,liquid and amorphous phases of silicon carbide.The simulated results indicate that amorphous network dviates from an ideal tetrahedral geometry due to the influence of C bonding.A long-range zinc-blended structure is acquired by crystal phase simulation.The result from liquid phase simulation shows that silicon has 5.64 nearest neighbors and carbon has 3.67 nearest neighbors.Two peaks at around 66° and 120°from bond-angle distribution indicate that a number of C atoms are sp 2 bonding and form graphitic-like structure.Amorphous structure retain liquid network,but the coordination number of carbon and silicon decreases.The coordination number 4.24 for silicon shows that silicon retains tetrahedral structure with sp 3 bonding.