Heyn Christian, Zocher Michel, Schnüll Sandra, Hansen Wolfgang
Institut für Nanostruktur- und Festkörperphysik, Center for Hybrid Nanostructures (CHYN), Universität Hamburg, Jungiusstraße 11, Hamburg, D-20355, Germany.
Nanoscale Res Lett. 2016 Dec;11(1):428. doi: 10.1186/s11671-016-1648-6. Epub 2016 Sep 26.
Self-assembled nanoholes are drilled into (001) AlGaAs surfaces during molecular beam epitaxy (MBE) using local droplet etching (LDE) with Al droplets. It is known that this process requires a small amount of background arsenic for droplet material removal. The present work demonstrates that the As background can be supplied by both a small As flux to the surface as well as by the topmost As layer in an As-terminated surface reconstruction acting as a reservoir. We study the temperature-dependent evaporation of the As topmost layer with in situ electron diffraction and determine an activation energy of 2.49 eV. After thermal removal of the As topmost layer droplet etching is studied under well-defined As supply. We observe with decreasing As flux four regimes: planar growth, uniform nanoholes, non-uniform holes, and droplet conservation. The influence of the As supply is discussed quantitatively on the basis of a kinetic rate model.
在分子束外延（MBE）过程中，使用含铝液滴的局部液滴蚀刻（LDE）在（001）AlGaAs表面钻出自组装纳米孔。已知该过程需要少量的背景砷来去除液滴材料。目前的工作表明，砷背景既可以由向表面的少量砷通量提供，也可以由作为储存库的砷终止表面重构中的最顶层砷层提供。我们用原位电子衍射研究了最顶层砷层的温度依赖性蒸发，并确定了2.49 eV的活化能。在热去除最顶层砷层后，在明确的砷供应条件下研究液滴蚀刻。随着砷通量的降低，我们观察到四种状态：平面生长、均匀纳米孔、非均匀孔和液滴保留。基于动力学速率模型定量讨论了砷供应的影响。
