Center for Electron Microscopy, Steyrergasse 17, 8010 Graz, Austria.
ACS Appl Mater Interfaces. 2014 Feb 26;6(4):2987-95. doi: 10.1021/am405591d. Epub 2014 Feb 17.
The gas flux direction in focused electron beam induced processes can strongly destabilize the morphology on the nanometer scale. We demonstrate how pattern parameters such as position relative to the gas nozzle, axial rotation, scanning direction, and patterning sequence result in different growth modes for identical structures. This is mainly caused by nanoscale geometric shadowing, particularly when shadowing distances are comparable to surface diffusion lengths of (CH3)3-Pt-CpCH3 adsorbates. Furthermore, two different adsorbate replenishment mechanisms exist and are governed by either surface diffusion or directional gas flux adsorption. The experimental study is complemented by calculations and dynamic growth simulations which successfully emulate the observed morphology instabilities and support the proposed growth model.
在聚焦电子束诱导过程中，气体通量方向会强烈地使纳米尺度的形貌变得不稳定。我们展示了图案参数（如相对于气体喷嘴的位置、轴向旋转、扫描方向和图案化顺序）如何导致相同结构产生不同的生长模式。这主要是由纳米级几何阴影引起的，特别是当阴影距离与（CH3）3-Pt-CpCH3 吸附物的表面扩散长度相当时。此外，存在两种不同的吸附物补给机制，分别受表面扩散或定向气流吸附控制。实验研究得到了计算和动态生长模拟的补充，这些模拟成功地模拟了观察到的形貌不稳定性，并支持了所提出的生长模型。
