Heyn Christian, Bartsch Thorben, Sanguinetti Stefano, Jesson David, Hansen Wolfgang
Institut für Angewandte Physik, Universität Hamburg, Jungiusstr. 11, Hamburg, 20355 Germany.
L-NESS and Dipartimento di Scienza dei Materiali, Universitá di Milano Bicocca, Milano, Via Cozzi 5320125 Italy.
Nanoscale Res Lett. 2015 Feb 13;10:67. doi: 10.1186/s11671-015-0779-5. eCollection 2015.
Local droplet etching (LDE) utilizes metal droplets during molecular beam epitaxy for the self-assembled drilling of nanoholes into III/V semiconductor surfaces. An essential process during LDE is the removal of the deposited droplet material from its initial position during post-growth annealing. This paper studies the droplet material removal experimentally and discusses the results in terms of a simple model. The first set of experiments demonstrates that the droplet material is removed by detachment of atoms and spreading over the substrate surface. Further experiments establish that droplet etching requires a small arsenic background pressure to inhibit re-attachment of the detached atoms. Surfaces processed under completely minimized As pressure show no hole formation but instead a conservation of the initial droplets. Under consideration of these results, a simple kinetic scaling model of the etching process is proposed that quantitatively reproduces experimental data on the hole depth as a function of the process temperature and deposited amount of droplet material. Furthermore, the depth dependence of the hole side-facet angle is analyzed.
局部液滴蚀刻（LDE）在分子束外延过程中利用金属液滴在III/V族半导体表面进行自组装纳米孔钻孔。LDE过程中的一个关键步骤是在生长后退火期间将沉积的液滴材料从其初始位置去除。本文通过实验研究了液滴材料的去除情况，并根据一个简单模型讨论了结果。第一组实验表明，液滴材料是通过原子脱离并在衬底表面扩散而被去除的。进一步的实验证实，液滴蚀刻需要一个较小的砷背景压力来抑制脱离原子的重新附着。在完全最小化的砷压力下处理的表面没有形成孔洞，而是保留了初始液滴。考虑到这些结果，提出了一个简单的蚀刻过程动力学缩放模型，该模型定量地再现了作为工艺温度和液滴材料沉积量函数的孔深实验数据。此外，还分析了孔侧面角度的深度依赖性。
