Mechanisms, models and methods of vapor deposition
Mechanisms, models and methods of vapor deposition
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DOI：
10.1016/s0079-6425(00)00009-8
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发表时间：
2001
影响因子：
37.4
通讯作者：
H. Wadley;Xiaowang W. Zhou;R. Johnson;M. Neurock
中科院分区：
文献类型：
--
作者：
H. Wadley;Xiaowang W. Zhou;R. Johnson;M. Neurock
在气相沉积生长过程中，入射到薄膜表面的原子通量的凝聚和组装是复杂的。通过改变通量、调节薄膜温度、用高能（辅助）粒子照射生长表面或选择性使用表面活性剂来调节生长过程，对于实现高性能薄膜所需的原子级完美水平至关重要。用于分析气相沉积薄膜和纳米粒子生长的多尺度建模方法已经开始出现并受到审查。密度泛函理论等从头算方法用于提供有关原子组装基本机制的关键见解。最近的工作探索了缺陷表面上原子跳跃的转变路径和动力学，并正在研究表面活性剂在控制表面原子迁移率方面的作用。基于嵌入原子方法、Tersoff 和键序势的新型原子间势现在可以与分子动力学相结合，以研究气相合成过程的许多方面。例如，溅射靶材发射的原子的能量分布、热原子对表面扩散机制的影响以及辅助离子在控制表面粗糙度中的作用都可以通过这种方法进行研究。它们还能够有效评估原子组装过程中存在的许多激活势垒，并将其用作多路径动力学蒙特卡罗模型或薄膜生长连续模型的输入。这种层次化的建模技术现在允许将许多原子组装机制纳入薄膜生长模拟中，以提高保真度。我们发现了新的机会，将这种建模方法扩展到日益复杂的材料系统的增长。以表现出巨磁阻的金属多层膜的生长作为案例研究，我们表明该方法还可以识别新颖的生长过程，利用吸附原子能量控制、极低能量离子辅助或高流动性、低溶解度化学物质（表面活性剂）来控制表面扩散控制的薄膜生长。这种方法似乎能够创建具有异常光滑、非混合界面以及显着优异的磁阻的多层材料。
The condensation and assembly of atomic fluxes incident upon the surface of a thin film during its growth by vapor deposition is complex. Mediating the growth process by varying the flux, adjusting the film temperature, irradiating the growth surface with energetic (assisting) particles or making selective use of surfactants is essential to achieve the level of atomic scale perfection needed for high performance films. A multiscale modeling method for analyzing the growth of vapor deposited thin films and nanoparticles has begun to emerge and is reviewed. Ab-initio methods such as density functional theory are used to provide key insights about the basic mechanisms of atomic assembly. Recent work has explored the transition paths and kinetics of atomic hopping on defective surfaces and is investigating the role of surfactants to control surface atom mobility. New forms of interatomic potentials based upon the embedded atom method, Tersoff and bond order potentials can now be combined with molecular dynamics to investigate many aspects of vapor phase synthesis processes. For example, the energy distribution of atoms emitted from sputtering targets, the effects of hot atom impacts upon the mechanisms of surface diffusion, and the role of assisting ions in controlling surface roughness can all be investigated by this approach. They also enable the many activation barriers present during atomic assembly to be efficiently evaluated and used as inputs in multipath kinetic Monte Carlo models or continuum models of film growth. This hierarchy of modeling techniques now allows many of the atomic assembly mechanisms to be incorporated in film growth simulations of increasing fidelity. We identify new opportunities, to extend this modeling approach to the growth of increasingly complicated material systems. Using the growth of metal multilayers that exhibit giant magnetoresistance as a case study, we show that the approach can also lead to the identification of novel growth processes that utilize adatom energy control, very low energy ion assistance, or highly mobile, low solubility chemical species (surfactants) to control surface diffusion controlled film growth. Such approaches appear capable of enabling the creation of multilayered materials with exceptionally smooth, unmixed interfaces, with significantly superior magnetoresistance.