Investigation of strain in self-assembled multilayer InAs/GaAs quantum dot heterostructures

The self-assembled InAs/GaAs multilayer quantum dots (QDs) are formed in a strain-driven process due to the lattice mismatch of the InAs/GaAs system. We have investigated strain interaction in 10 layer QD heterostructure with varying thicknesses of combination capping (InAlGaAs and GaAs) by means of...

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Bibliographic Details
Published in:Journal of crystal growth 2010-02, Vol.312 (5), p.724-729
Main Authors: Adhikary, S., Halder, N., Chakrabarti, S., Majumdar, S., Ray, S.K., Herrera, M., Bonds, M., Browning, N.D.
Format: Article
Language:English
Subjects:
A1. Nanostructure
A3.Molecular beam epitaxy
A3.Quantum dots
B2.Semiconducting III–V materials
Capping
Condensed matter: structure, mechanical and thermal properties
Cross-disciplinary physics: materials science
rheology
Exact sciences and technology
Gallium arsenide
Gallium arsenides
Heterostructures
Indium arsenides
Materials science
Methods of nanofabrication
Nanoscale materials and structures: fabrication and characterization
Other topics in nanoscale materials and structures
Physics
Quantum dots
Scanning transmission electron microscopy
Self-assembled multilayers
Self-assembly
Strain
Structure of solids and liquids
crystallography
Structure of specific crystalline solids
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Summary:The self-assembled InAs/GaAs multilayer quantum dots (QDs) are formed in a strain-driven process due to the lattice mismatch of the InAs/GaAs system. We have investigated strain interaction in 10 layer QD heterostructure with varying thicknesses of combination capping (InAlGaAs and GaAs) by means of scanning transmission electron microscopy (STEM), high-resolution X-ray diffraction (HRXRD) and Raman scattering. STEM micrographs reveal nice stacking of defect-free dots in all the layers of the sample having a thick combination capping. The periodic satellite peaks in the HRXRD rocking curve show good formation of dots and an indication of reduced compressive strain in the heterostructure with increased capping thickness. We detect an upward phonon frequency shift for InAs QDs in the low-temperature Raman study, which is believed to be due to strain relaxation as the thickness of the capping layer increases. The sample with thick combination capping showed better optical emission properties.
ISSN:0022-0248
1873-5002
DOI:10.1016/j.jcrysgro.2009.11.067