C20与Si(100)-(2×1)重构表面相互作用的计算机模拟研究

COMPUTER SIMULATIONS OF THE INTERACTIONS BETWEEN C20 AND A RECONSTRUCTED SILICON (100)-(2×1) SURFACE

  • 摘要: 用分子动力学的方法模拟研究了低能C20与Si(100)-(2×1)重构表面的相互作用过程。将描述C、Si结构的Tersoff势和描述原子间短程排斥的KrC势相结合,建立了一个混合势作为原子间的相互作用模型。荷能C20垂直轰击到Si(100)-(2×1)表面后,由于在<110>方向受到非对称力场的作用而产生横向的集体运动,改变的入射能量导致C20与Si(100)-(2×1)表面最接近的垂直距离不同,从而受到不同的横向力场的作用而产生不同的表面运动特性。C20能量耗尽后稳定吸附在Si(100)-(2×1)表面,且只有两个稳定吸附位置,即二聚体(dimer)和"峡谷"(trough)位,这两个吸附位置的存在可用C20与Si(100)-(2×1)表面之间非对称的表面力场分布来定性解释。最终C20与Si(100)-(2×1)表面有强烈的化学键形成。模拟结果与STM的实验观察结果进行了比较

     

    Abstract: The interaction between a low energy C20 molecule and a reconstructed silicon (100)-(2×1) surface is simulated with a hybrid potential, which is a combination of the Tersoff potential and the repulsive KrC potential. After impacting of the silicon substrate, the C20 cluster is found to move along 〈110〉 direction as a rigid sphere. The collective motion of the C20 molecule can be explained by the anisotropic force field between the dimerized silicon surface and the C20 molecule. Different impact energies lead to different closet interaction distances between the C20 molecule and the silicon surface, which generate different distributions of the lateral force field. Changes in the force field lead to different kinetic behavior of the C20 along the 〈110〉 direction. Finally, the C20 comes to rest on the surface when its kinetic energy is consumed up. In the trough or on the top of a dimer are the two energy favored adsorption sites of the C20 on the silicon surface. The formation of C-Si bonds is an indication that strong bindings between the C20 and the silicon surface exist. These results are consistent with experimental findings of C20 molecules adsorbed on a reconstructed silicon surface.

     

/

返回文章
返回