Thermally controlled widening of droplet etched nanoholes
1 Institut für Angewandte Physik und Zentrum für Mikrostrukturforschung, Jungiusstraße 11, Hamburg 20355, Germany
2 School of Physics and Astronomy, Cardiff University, Cardiff CF24 3AA, UK
Nanoscale Research Letters 2014, 9:285 doi:10.1186/1556-276X-9-285Published: 9 June 2014
We describe a method to control the shape of nanoholes in GaAs (001) which combines the technique of local droplet etching using Ga droplets with long-time thermal annealing. The cone-like shape of inverted nanoholes formed by droplet etching is transformed during long-time annealing into widened holes with flat bottoms and reduced depth. This is qualitatively understood using a simplified model of mass transport incorporating surface diffusion and evaporation. The hole diameter can be thermally controlled by varying the annealing time or annealing temperature which provides a method for tuning template morphology for subsequent nanostructure nucleation. We also demonstrate the integration of the combined droplet/thermal etching process with heteroepitaxy by the thermal control of hole depth in AlGaAs layers.