Self-assembled quantum dots with tunable thickness of the wetting layer: Role of vertical confinement on interlevel spacing

2009 ◽  
Vol 80 (8) ◽  
Author(s):  
Lijuan Wang ◽  
Vlastimil Křápek ◽  
Fei Ding ◽  
Felicity Horton ◽  
Andrei Schliwa ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Wetting Layer ◽  
Self Assembled

Growth and Overgrowth of Ge/Si Quantum Dots: An Observation by Atomic Resolution HAADF-STEM Imaging

2004 ◽  
Vol 832 ◽  
Author(s):  
Dan Zhi ◽  
Paul A. Midgley ◽  
Rafal E. Dunin-Borkowski ◽  
Bruce A. Joyce ◽  
Don W. Pashley ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Direct Analysis ◽  
Lateral Spreading ◽  
Dark Field ◽  
Atomic Scale ◽  
Wetting Layer ◽  
Compositional Evolution ◽  
Scanning Transmission ◽  
Annular Dark Field ◽  
Self Assembled

ABSTRACTThe formation of self-assembled quantum dots (QD) is of increasing interest for applications in optical, nanoelectronic, biological and quantum computing systems. From the perspective of fabrication technology, there are great advantages if the whole device can be made using a single Si substrate. Furthermore, GeSi is a model semiconductor system for fundamental studies of growth and material properties. In practice, as the MBE growth of heterostructures is inherently a non-equilibrium process, the formation of self-assembled nanostructures is both complex and sensitive to growth and overgrowth conditions. The morphology, structure and composition of QDs can all change during growth. It is therefore crucial to understand their structures at different stages of growth at the atomic scale. Here, the characterization of QD growth using high-resolution high angle annular dark field (HAADF) scanning transmission electron microscopy (STEM) imaging is presented. Both the formation of uncapped QDs and the effect of the encapsulation are investigated, and the morphological and compositional evolution of the QDs and wetting layers are observed directly at the atomic scale for the first time. During encapsulation, the Ge content in the centres of the QD remains unchanged, despite significant intermixing, lateral spreading and a laterally inhomogeneous Ge distribution inside the Ge QD. The initial non-uniform wetting layer for the uncapped Ge QD becomes uniform after encapsulation, and a 3-monolayer-thick core with ∼ 60% Ge content is formed in the 2 nm-thick wetting layer with an average Ge content of ∼ 30%. The results were obtained by direct analysis of the Z-contrast STEM imaging without involving complex image simulations.

scholarly journals Influence of wetting-layer wave functions on phonon-mediated carrier capture into self-assembled quantum dots

2006 ◽  
Vol 74 (19) ◽  
Author(s):  
Troels Markussen ◽  
Philip Kristensen ◽  
Bjarne Tromborg ◽  
Tommy Winther Berg ◽  
Jesper Mørk
Keyword(s):  
Quantum Dots ◽  
Wave Functions ◽  
Wetting Layer ◽  
Carrier Capture ◽  
Self Assembled

Polarization dynamics in self-assembled CdSe/ZnSe quantum dots: The role of excess energy

2003 ◽  
Vol 67 (15) ◽  
Author(s):  
M. Scheibner ◽  
G. Bacher ◽  
S. Weber ◽  
A. Forchel ◽  
Th. Passow ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Excess Energy ◽  
Self Assembled

Role of different cap layers tuning the wavelength of self-assembled InAs/GaAs quantum dots

2003 ◽  
Vol 15 (31) ◽  
pp. 5383-5388 ◽  
Author(s):  
Z Gong ◽  
Z D Fang ◽  
X H Xu ◽  
Z H Miao ◽  
Z C Niu ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Self Assembled

scholarly journals Single Self-Assembled InAs/GaAs Quantum Dots in Photonic Nanostructures: The Role of Nanofabrication

2018 ◽  
Vol 9 (6) ◽  
Author(s):  
Jin Liu ◽  
Kumarasiri Konthasinghe ◽  
Marcelo Davanço ◽  
John Lawall ◽  
Vikas Anant ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Self Assembled

Morphology of Self-Assembled InAs Quantum Dots on GaAs(001)

2001 ◽  
Vol 696 ◽  
Author(s):  
F. Arciprete ◽  
F. Patella ◽  
M. Fanfoni ◽  
S. Nufris ◽  
E. Placidi ◽  
...  
Keyword(s):  
Nucleation And Growth ◽  
The Self ◽  
Two Dimensional ◽  
Wetting Layer ◽  
Inas Quantum Dots ◽  
Initial Formation ◽  
Force Microscopy ◽  
Atomic Force ◽  
Self Assembled

AbstractWe have followed by Atomic Force Microscopy (AFM) the epitaxial growth of InAs on GaAs(001) starting from the initial formation of a strained two-dimensional wetting layer up to the self-assembled nucleation and growth of 3D nanoparticles. In this work we underline many aspects of the morphology of this system, which substantiate the role either of kinetics on thermodynamics in the process of growth as well as the role of surface instabilities in controlling lateral ordering of the nanoaggregates.

scholarly journals Kondo-excitons and Auger processes in self-assembled quantum dots

2002 ◽  
Vol 737 ◽  
Author(s):  
A. O. Govorov ◽  
K. Karrai ◽  
R. J. Warburton ◽  
A. V. Kalameitsev
Keyword(s):  
Magnetic Field ◽  
Quantum Dots ◽  
Electron Spin ◽  
Electron Gas ◽  
Kondo Temperature ◽  
Two Dimensional ◽  
Wetting Layer ◽  
Voltage Dependent ◽  
Self Assembled ◽  
The Continuum

ABSTRACTWe describe theoretically novel excitons in self-assembled quantum dots interacting with a two-dimensional (2D) electron gas in the wetting layer. In the presence of the Fermi sea, the optical lines become strongly voltage-dependent. If the electron spin is nonzero, the width of optical lines is given by kBTK, where TK is Kondo temperature. If the spin is zero, the exciton couples with the continuum due to Auger-like processes. This leads to anticrossings in a magnetic field. Such states can be called Kondo-Anderson excitons. Some of the described phenomena are observed in recent experiments.

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