Dynamics of the Growth of InAs Quantum Dots on GaAs(001) Substrates

1999 ◽  
Vol 571 ◽  
Author(s):  
D.I. Westwood ◽  
I.H. Brown ◽  
D.N.J. Linsell ◽  
C.C. Matthai
Keyword(s):  
Quantum Dots ◽  
Three Dimensional ◽  
Wetting Layer ◽  
Molecular Beam Epitaxial ◽  
Reflectance Anisotropy ◽  
Standard Rate ◽  
Conventional Models ◽  
Molecular Beam Epitaxial Growth

ABSTRACTStandard rate equation models of island formation in the InAs/GaAs(001) system have been reassessed in terms of new experimental evidence from real time in-situ reflectance anisotropy spectroscopy (RAS) measurements. These measurements have revealed the behaviour and role of the wetting layer in the modified Stranski-Krastanov growth mode during molecular beam epitaxial growth showing that it can continue to significantly increase in thickness following the onset of islanding. The presence of two dimensional (2D) islands, which act as precursors to three dimensional (3D) islands (the quantum dots) in conventional models, does in principle allow an extension of the “wetting layer”. However, it has been found necessary to extend the standard model to include extra terms that allow material to be incorporated into (and detach from) the wetting layer and which cannot convert to 3D islands. With this improved model, it is found possible to achieve agreement with the RAS measurements.

Self-assembled quantum dots and nanoholes by molecular beam epitaxial growth and atomically precise in situ etching

2002 ◽  
Vol 722 ◽  
Author(s):  
S. Kiravittaya ◽  
R. Songmuang ◽  
O. G. Schmidt
Keyword(s):  
Quantum Dots ◽  
Molecular Beam ◽  
Flat Surface ◽  
Local Strain ◽  
Growth Conditions ◽  
Etching Depth ◽  
Molecular Beam Epitaxial ◽  
Self Assembled ◽  
Molecular Beam Epitaxial Growth

AbstractEnsembles of homogeneous self-assembled quantum dots (QDs) and nanoholes are fabricated using molecular beam epitaxy in combination with atomically precise in situ etching. Self-assembled InAs QDs with height fluctuations of ±5% were grown using a very low indium growth rate on GaAs (001) substrate. If these dots are capped with GaAs at low temperature, strong room temperature emission at 1.3 νm with a linewidth of 21 meV from the islands is observed. Subsequently, we fabricate homogeneous arrays of nanoholes by in situ etching the GaAs surface of the capped InAs QDs with AsBr3. The depths of the nanoholes can be tuned over a range of 1-6 nm depending on the nominal etching depth and the initial capping layer thickness. We appoint the formation of nanoholes to a pronounced selectivity of the AsBr3 to local strain fields. The holes can be filled with InAs again such that an atomically flat surface is recovered. QDs in the second layer preferentially form at those sites, where the holes were initially created. Growth conditions for the second InAs layer can be chosen in such a way that lateral QD molecules form on a flat surface.

Diffraction Studies of the Growth of Strained Epitaxial Layers

1989 ◽  
Vol 160 ◽  
Author(s):  
G.J. Whaley ◽  
P.I. Cohen
Keyword(s):  
Cluster Formation ◽  
Three Dimensional ◽  
Lattice Relaxation ◽  
Misfit Strain ◽  
High Energy ◽  
Layer By Layer ◽  
Molecular Beam Epitaxial ◽  
Molecular Beam Epitaxial Growth ◽  
Strain Dependent

AbstractThe molecular beam epitaxial growth of strained InGaAs films grown on GaAs(100) substrates has been studied using in situ reflection high-energy electron diffraction (RHEED). Both the intensity, shape and position of the diffracted beams were monitored during growth. Growth was found to be layer-by-layer up to a strain dependent thickness, at which point three-dimensional clusters were formed. These clusters exhibited (114) facets and were elongated in the [011] direction. The onset of 3D cluster formation was simultaneous with measurable lattice relaxation. The relaxation was determined using electromagnetic deflection of the RHEED pattern across two detectors. With this arrangement, the lattice constant could be measured to within 0.003Å. The onset could be delayed by lowering the growth temperature. For misfit strain greater than about 2%, the onset occurs at thicknesses less than the Matthews-Blakeslee critical thickness. For smaller strains, the onset occurs at larger thicknesses.

Direct observation of strain in InAs quantum dots and cap layer during molecular beam epitaxial growth using in situ X-ray diffraction

2015 ◽  
Vol 118 (18) ◽  
pp. 185303 ◽  
Author(s):  
Kenichi Shimomura ◽  
Hidetoshi Suzuki ◽  
Takuo Sasaki ◽  
Masamitu Takahasi ◽  
Yoshio Ohshita ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Epitaxial Growth ◽  
Direct Observation ◽  
Molecular Beam ◽  
X Ray Diffraction ◽  
Inas Quantum Dots ◽  
X Ray ◽  
Molecular Beam Epitaxial ◽  
Molecular Beam Epitaxial Growth

Molecular beam epitaxial growth of InAs self-assembled quantum dots with light-emission at 1.3μm

2000 ◽  
Vol 208 (1-4) ◽  
pp. 93-99 ◽  
Author(s):  
Y Nakata ◽  
K Mukai ◽  
M Sugawara ◽  
K Ohtsubo ◽  
H Ishikawa ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Epitaxial Growth ◽  
Molecular Beam ◽  
Light Emission ◽  
Molecular Beam Epitaxial ◽  
Self Assembled ◽  
Molecular Beam Epitaxial Growth

scholarly journals 1 ML Wetting Layer upon Ga(As)Sb Quantum Dot (QD) Formation on GaAs Substrate Monitored with Reflectance Anisotropy Spectroscopy (RAS)

2018 ◽  
Vol 2018 ◽  
pp. 1-7
Author(s):  
Henning Fouckhardt ◽  
Johannes Strassner ◽  
Thomas H. Loeber ◽  
Christoph Doering
Keyword(s):  
Gaas Substrate ◽  
Semiconductor Quantum Dots ◽  
Ex Situ ◽  
Difference Spectroscopy ◽  
Wetting Layer ◽  
Reflectance Anisotropy ◽  
Atomic Force ◽  
Monitoring Technique ◽  
Scientific Dispute

III/V semiconductor quantum dots (QD) are in the focus of optoelectronics research for about 25 years now. Most of the work has been done on InAs QD on GaAs substrate. But, e.g., Ga(As)Sb (antimonide) QD on GaAs substrate/buffer have also gained attention for the last 12 years. There is a scientific dispute on whether there is a wetting layer before antimonide QD formation, as commonly expected for Stransky-Krastanov growth, or not. Usually ex situ photoluminescence (PL) and atomic force microscope (AFM) measurements are performed to resolve similar issues. In this contribution, we show that reflectance anisotropy/difference spectroscopy (RAS/RDS) can be used for the same purpose as an in situ, real-time monitoring technique. It can be employed not only to identify QD growth via a distinct RAS spectrum, but also to get information on the existence of a wetting layer and its thickness. The data suggest that for antimonide QD growth the wetting layer has a thickness of 1 ML (one monolayer) only.

MBE Growth and Ultrahigh Temperature Processing of High-Quality AlN Films

1999 ◽  
Vol 587 ◽  
Author(s):  
Z.Y. Fan ◽  
G. Rong ◽  
N. Newman ◽  
David J. Smith ◽  
D. Chandrasekhar
Keyword(s):  
High Quality ◽  
Mbe Growth ◽  
Rocking Curve ◽  
Molecular Beam Epitaxial ◽  
Dislocation Densities ◽  
High Kinetic Energy ◽  
Nitrogen Ion ◽  
Ultrahigh Temperature ◽  
Molecular Beam Epitaxial Growth

AbstractMolecular beam epitaxial growth of AlN on sapphire and 6H-SiC has been performed utilizing mono-energetic activated nitrogen ion beams (2-80 eV kinetic energies). The growth temperature of AlN in MBE is found to be limited by the sticking coefficient of incident reactants. The combination of elevated growth temperatures (1050-1150°C), high kinetic-energy reactive nitrogen (>40 eV) and post-growth thermal processing (1150-1350°C) produces high-quality AlN thin-f ilms with narrow rocking curve widths (<2 arcmin) and low dislocation densities (<∼3×108cm−2). In contrast, the use of in-situ step anneals during synthesis did not achieve similar quality materials.

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