Low-energy Si And Si (001) 2 ¡Á 1 Reconstruction Of The Surface Interaction Of Molecular Dynamics Simulations

In this thesis, we aim to present a detail study on the interaction between low kinetic energy incident Si atoms and the Si(001) surface by the molecular dynamics (MD) method using the Tersoff potential.The thesis consists of six chapters. In chapterⅠ, we present a brief review of the thin film growth theory, the method of the film research, and summarize some important results of the interaction between incident atoms and the surface. A brief introduction to the molecular dynamics method and some key skills for the simulation can be found in chapterⅡ. In chapterⅢ, the 2×1 reconstruction and the relaxation toward bulk of the Si(001) surface can be observed. The process of the reconstruction and the relaxation can complete within 5ns at 300K, and the process are accelerated with the temperature increasing. In chapterⅣ, we simulated the interaction between a bombarding Si atom with 0.03eV kinetic energy and the substrate surface(both reconstructed and unreconstructed). The results show that the interaction can react completely in a few picoseconds. The max binding energy of an adatom to Si(001)2×1 reconstructed surface is about 2.99eV while to the Si(001) unreconstructed surface is 2.44eV. For the Si(001)2×1 reconstructed surface, we find that: a single, 0.03eV incident Si atom is able to open a surface dimer in dozens of femtoseconds after the interaction taking place from position 5 or position 6, while the atom bombarded from position 1, 2, 3, 4 can not. In chapterⅤ, We simulated a deposition process about 64 incident Si atoms on the Si(001) 2×1 reconstructed surface. The results show that: the deposition of the low kinetic energy incident atoms on the Si(001)2×1 reconstructed surface is a complicated process. We find that the morphology of the deposited atoms is more regular and the roughness of the new growth layer is lower with the substrate temperature increasing. The morphology of the new growth layer is more regular with the initial incident kinetic energy increasing. But if the kinetic energy is too large(>3eV), the incident atoms can destroy the arrangement of the substrate surface atoms which is harmful to the film growth. The site exchanges between bombarding atoms and the substrate atoms are also observed. Finally, we summarize all conclusions in chapterⅥ.