title: Dynamics of mass transport during nanohole drilling by local droplet etching.
abstract: 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.
authors: Institut für Angewandte Physik, Universität Hamburg, Jungiusstr. 11, Hamburg, 20355 Germany.
authors: Christian
authors: C
authors: Heyn
authors: Institut für Angewandte Physik, Universität Hamburg, Jungiusstr. 11, Hamburg, 20355 Germany.
authors: Thorben
authors: T
authors: Bartsch
authors: L-NESS and Dipartimento di Scienza dei Materiali, Universitá di Milano Bicocca, Milano, Via Cozzi 5320125 Italy.
authors: Stefano
authors: S
authors: Sanguinetti
authors: School of Physics and Astronomy, Cardiff University, Cardiff, CF24 3AA United Kingdom.
authors: David
authors: D
authors: Jesson
authors: Institut für Angewandte Physik, Universität Hamburg, Jungiusstr. 11, Hamburg, 20355 Germany.
authors: Wolfgang
authors: W
authors: Hansen
keywords: Droplet epitaxy; Droplet etching; Growth modelling; Mass transport; Nanoholes; Self-assembly; Semiconductor nanostructures