Smith Daryl A, Fowlkes Jason D, Rack Philip D
Department of Materials Science and Engineering, The University of Tennessee, Knoxville, TN 37996, USA.
Nanotechnology. 2008 Oct 15;19(41):415704. doi: 10.1088/0957-4484/19/41/415704. Epub 2008 Sep 4.
The effects that adsorbed precursor surface diffusion has on electron beam induced deposition are explored via a three-dimensional Monte Carlo simulation. Initially the growth rate and resolution are compared for a common set of deposition conditions with a variable surface diffusion coefficient ranging from 0 to 1 × 10(-8) cm(2) s(-1). The growth rate and resolution are shown to both be enhanced as the growth changes from a mass transport limited regime to a reaction rate limited regime. The complex interplay between the vertical growth rate, the lateral growth rate, the interaction volume and the adsorbed and diffused precursor species are discussed. A second scenario is also simulated in which only gas diffused from a constant source at the perimeter of the simulation boundary is assumed (no gas phase adsorption). At low diffusion coefficients, the diffusing gas is consumed by secondary and backscattered electrons and experimentally observed ring-like structures are generated. At higher diffusion coefficients, the diffusion length is sufficient for the precursor atoms to diffuse to the center (and up the pillar sidewalls) to generate nanowires.
通过三维蒙特卡罗模拟研究了吸附前驱体表面扩散对电子束诱导沉积的影响。最初，在一组常见的沉积条件下，比较了生长速率和分辨率，表面扩散系数可变，范围从0到1×10⁻⁸ cm² s⁻¹。结果表明，随着生长从质量传输限制 regime 转变为反应速率限制 regime，生长速率和分辨率均得到提高。讨论了垂直生长速率、横向生长速率、相互作用体积以及吸附和扩散的前驱体物种之间的复杂相互作用。还模拟了第二种情况，即仅假设从模拟边界周边的恒定源扩散的气体（无气相吸附）。在低扩散系数下，扩散气体被二次电子和背散射电子消耗，并产生实验观察到的环状结构。在较高的扩散系数下，扩散长度足以使前驱体原子扩散到中心（并沿柱侧壁向上扩散）以生成纳米线。
