Fabrication of Semiconductor Quantum Dot Molecules: Droplet Epitaxy and Local Oxidation Nanolithography Techniques - Quantum Dot Molecules - page 11

Fig. 1.7 3D rendered AFM images of a typical ( a ) nanohole, ( b ) single QD, and ( c ) QDM obtained
by droplet epitaxy etching technique and posterior preferential nucleation of InAs material. Profiles
on these nanostructures along the GaAs [1 1 0] direction are shown at the right . Reprinted (adapted)
with permission from [ 20 ]. Copyright 2009 American Chemical Society

III atoms (Ga and In) into the nanoholes for the different As 2 pressures used in each
case. In this regard, special relevancy has the crystalline orientation of the facets
defined inside the nanoholes, which eventually conditions the nucleation process
of In atoms [ 22 ]. On patterned substrates, apart from the GaAs (0 0 1) surface,
two different surfaces can be identified: (0 0 1) disoriented surfaces towards [1 1 0]
direction with step edges parallel to this direction that are Ga-terminated (A-type
facets), and (0 0 1) disoriented surfaces towards [1 − 1 0] direction with step edges