低能原子沉积在Pt(111)表面的分子动力学模拟

采用嵌入原子方法的原子间相互作用势,利用分子动力学方法模拟了六种贵金属原子(Ni,Pd,Pt,Cu,Ag,Au)分别在Pt(111)表面低能沉积的动力学过程.结果表明:随着入射能量从0.1eV升高到200eV,基体表面原子是按层迁移的,沉积过程对基体表面的影响和沉积原子在基体表层的作用均存在两个转变能量(ET1≈5eV,ET2≈70eV).当入射能量低于5eV时,基体表面几乎没有吸附原子和空位形成,沉积原子在基体表层几乎没有注入产生;当入射能量在5—70eV范围内时,沉积原子在基体表层有注入产生,其注入深度小于两个原子层,即为亚注入,此时吸附原子主要由基体表层原子形成,基体表面第三层以下没有空位形成;当入射能量高于70eV时,沉积原子的注入深度大于两个原子层,将会导致表面以下第三层形成空位,并且空位产额随入射能量的升高而急剧增加.基于分子动力学模拟的结果,对低能沉积作用下的薄膜生长以及最优沉积参数的选择进行了讨论.

Molecular dynamics simulation of low-energy bombardment on Pt(111)surface

The low-energy bombardments of noble metal atoms (Ni, Pd, Pt, Cu, Ag, Au) on Pt (111) surface are studied by molecular dynamics (MD) simulations. The atomic interaction potential with embedded atom is used in the simulation. The incident-energy effects on adatom yields, sputtering yields, and vacancy yields for different projectiles have been observed and summarized. When the incident energy E_in varies from 0.1 to 200 eV, surface atoms transfer layer by layer and the incident energy dependent transition occurs when the incident energy values are about 5 and 70 eV. When the incident energy is lower than 5 eV, projetiles are deposited as adatom and the value of defect yield is 0. While 70 eV > E_in > 5 eV, no atoms can be implanted into the depth beyond the second layer and the vacancy yield in the third layer is about 0. For the case of E_in > 70 eV, deposited atoms enter into the third layer. And then, vacancy occurs. Furthermore, defect yield sharply increases with the increase of incident energy. Based on the result of our MD simulations, a guide to the choice of optimum deposition parameters is suggested.