Abstract
For InAs/GaAs quantum dot system, the evolution of the wetting layer (WL) with the InAs deposition thickness has been studied by reflectance difference spectroscopy (RDS). Two transitions related to the heavy- and light-hole in the WL have been distinguished in RD spectra. Taking into account the strain and segregation effects, a model has been presented to deduce the InAs amount in the WL and the segregation coefficient of the indium atoms from the transition energies of heavy- and light-holes. The variation of the InAs amount in the WL and the segregation coefficient are found to rely closely on the growth modes. In addition, the huge dots also exhibits a strong effect on the evolution of the WL. The observed linear dependence of In segregation coefficient upon the InAs amount in the WL demonstrates that the segregation is enhanced by the strain in the WL.
Highlights
For InAs/GaAs quantum dot system, the evolution of the wetting layer (WL) with the InAs deposition thickness has been studied by reflectance difference spectroscopy (RDS)
RDS is a sensitive tool for characterizing the in-plane optical anisotropy (OA) of surfaces and quantum wells (QWs), in which the symmetries are reduced due to the surface reconstruction and the inversion asymmetry of the QWs, respectively [9, 10]
OA is expected for an InAs WL, which behaves as an asymmetric InGaAs QW due to Nanoscale Res Lett (2006) 1:79–83 the segregation effect [11]
Summary
For InAs/GaAs quantum dot system, the evolution of the wetting layer (WL) with the InAs deposition thickness has been studied by reflectance difference spectroscopy (RDS). No QD in samples 1–3 reflects a FM growth of the InAs layer. For the samples 4 and 5, a few InAs QDs appear in the surface, indicating a growth transition from FM into SK mode.
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