Headrick Randall L, Zhou Hua
Department of Physics and Materials Science Program, University of Vermont, Burlington, VT 05405, USA.
J Phys Condens Matter. 2009 Jun 3;21(22):224005. doi: 10.1088/0953-8984/21/22/224005. Epub 2009 May 12.
Ion bombardment of insulating surfaces such as Al(2)O(3) and SiO(2) produces ordered patterns of ripples. The ripple wavelength varies with ion energy, incidence angle and substrate temperature. A region of stability is also known to exist for near-normal incidence during Ar(+) ion bombardment, where initially rough surfaces are smoothened. A number of relaxation mechanisms are found to be operative under specific conditions, including: surface-confined viscous flow, impact-induced lateral currents and impact-assisted surface diffusion during ion bombardment at high temperatures. Most of the experimentally observed phenomena are explained through extension of the Bradley-Harper theory by the addition of these new processes. Phenomena that are not explained by the linear theory, such as the saturation of surface amplitude during the formation of ripples, are thought to arise from nonlinear effects. This contribution describes the present status of the linear theory relevant to this class of materials and recent experimental results.
对诸如Al₂O₃和SiO₂等绝缘表面进行离子轰击会产生规则的波纹图案。波纹波长随离子能量、入射角和衬底温度而变化。已知在Ar⁺离子轰击期间，近垂直入射时存在一个稳定区域，在此区域内，初始粗糙的表面会变得平滑。发现在特定条件下有多种弛豫机制起作用，包括：表面受限粘性流动、碰撞诱导的横向电流以及高温下离子轰击期间的碰撞辅助表面扩散。通过添加这些新过程扩展布拉德利 - 哈珀理论，解释了大多数实验观察到的现象。线性理论无法解释的现象，如波纹形成过程中表面振幅的饱和，被认为是由非线性效应引起的。本论文阐述了与这类材料相关的线性理论的现状以及近期的实验结果。
