Abstract
For InAs/GaAs(001) quantum dot (QD) system, the wetting layer (WL) evolution and its temperature dependence were studied using reflectance difference spectroscopy and were analyzed with a rate equation model. WL thicknesses showed a monotonic increase at relatively low growth temperatures but showed an initial increase and then decrease at higher temperatures, which were unexpected from a thermodynamic understanding. By adopting a rate equation model, the temperature dependence of QD formation rate was assigned as the origin of different WL evolutions. A brief discussion on the indium desorption was given. Those results gave hints of the kinetic aspects of QD self-assembly.
Highlights
Epitaxial semiconductor quantum dots (QDs) have attracted much attention because of their application potential in novel optoelectronic devices [1,2,3]
One can see the light hole (LH) and heavy hole (HH) transition energies redshift almost linearly up to an InAs deposition rate of 0.085 ML/s, which is commonly known as the critical thickness (CT) of InAs QD formation, gradually saturate for further deposition
In order to have an intuitive understanding on the evolution, we calibrate the wetting layer (WL) thicknesses based on the transition energies obtained from the spectra [20]
Summary
Epitaxial semiconductor quantum dots (QDs) have attracted much attention because of their application potential in novel optoelectronic devices [1,2,3]. They are usually fabricated utilizing the lattice mismatch between the epitaxial layer and substrate or the StranskiKrastanov (SK) growth mode. It can be described as follows: for small coverage, two-dimensional (2D) layerby-layer growth and pseudomorphic formation of wetting layer (WL) take place. A controllable growth of QDs with desired properties requires a comprehensive understanding on the growth process. It is necessary to have a clear understanding of the WL evolution during the QD selfassembly
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