Structural characterization of nanoholes on AlGaSb surface to estimate dimensions of GaSb quantum dots

Abstract

Quantum dots (QDs) are used in applications such as quantum communication and quantum computing as single and entangled photon emitters. Due to their nanoscale dimensions, quantum confinement effects become pronounced. Hence particle in a box model is valid for such structures. This results in a direct correlation between optical properties and dimensions of a QD. Recently, GaSb QDs have been grown by filling nanoholes formed by local droplet etching (LDE). LDE is a two step method used for nanohole fabrication. Firstly, Al atoms are deposited on AlGaSb surface under small group V atmosphere to form Al droplets. Subsequently the sample is annealed in a small group V flux. At the end, nanoholes form in the AlGaSb surface. It is important to study dimensions of nanoholes formed by LDE which gives information about the QD dimensions formed by filling these nanoholes.

In this research work nanohole dimensions are studied using atomic force microscopy (AFM). The results show that increasing Al coverage in range θAl = 1.76-1.90 ML for droplet formation has an increasing effect on nanohole dimensions. The effect of increasing Al coverage on nanohole dimensions studied using two microscopy systems: Veeco Dimension 3100 and Veeco Dimension Icon. The results confirm that the dimensional data obtained from Veeco Dimension Icon is more reliable compared to data obtained from Veeco Dimension 3100.