scholarly journals Effect of Nucleation Parameters of Ge Quantum Dots Grown over Silicon Oxide by LPCVD

2007 ◽  
Vol 2 (2) ◽  
pp. 81-84
Author(s):  
S. N. M. Mestanza ◽  
I. Doi ◽  
N. C. Frateschi
Keyword(s):  
Quantum Dots ◽  
Silicon Oxide ◽  
Chemical Vapor ◽  
Force Microscopy ◽  
Nucleation Parameters ◽  
Atomic Force ◽  
Transmission Electron ◽  
Pressure Chemical ◽  
Mean Size ◽  
Germanium Quantum Dots

Germanium quantum dots (Ge-QD) were grown by Low Pressure Chemical Vapor Deposition (LPCVD) on Si nucleus previously grown on 3 nm thick SiO2 ultra thin film. Samples were analyzed by atomic force microscopy (AFM) and high resolution transmission electron microscopy (HRTEM). We report the analysis of the influence of the nucleation parameters on size and spatial distribution of Ge-QD. AFM images show a Ge-QD density of around 3.6x1010 cm-2, with an 11 nm mean size and 2.9 nm height. Finally, HRTEM investigation shows that the Ge-QD have a crystalline structure, i.e., they are nanocrystals.

InP Self Assembled Quantum Dot Lasers Grown on GaAs Substrates by Metalorganic Chemical Vapor Deposition

2001 ◽  
Vol 692 ◽  
Author(s):  
R. D. Dupuis ◽  
J. H. Ryou ◽  
R. D. Heller ◽  
G. Walter ◽  
D. A. Kellogg ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Quantum Dot ◽  
Chemical Vapor ◽  
Active Regions ◽  
Threshold Current ◽  
Double Quantum ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron ◽  
Inp Quantum Dots

AbstractWe describe the operation of lasers having active regions composed of InP selfassembled quantum dots embedded in In0.5Al0.3Ga0.2P grown on GaAs (100) substrates by MOCVD. InP quantum dots grown on In0.5Al0.3Ga0.2P have a high density on the order of about 1–2×10 cm−2 with a dominant size of about 10–15 nm for 7.5 ML growth.[1] These In0.5Al0.3Ga0.2P/InP quantum dots have previously been characterized by atomic-force microscopy, high-resolution transmission electron microscopy, and photoluminescence.[2] We report here the 300K operation of optically pumped red-emitting quantum dots using both double quantum-dot active regions and quantum-dot coupled with InGaP quantum-well active regions. Optically and electrically pumped 300K lasers have been obtained using this active region design; these lasers show improved operation compared to the lasers having QD-based active regions with threshold current densities as low as Jth ∼ 0.5 KA/cm2.

scholarly journals Density control of InP/GaInP quantum dots grown by metal-organic vapor-phase epitaxy

2018 ◽  
Vol 52 (4) ◽  
pp. 477
Author(s):  
D.V. Lebedev ◽  
N.A. Kalyuzhnyy ◽  
S.A. Mintairov ◽  
K.G. Belyaev ◽  
M.V. Rakhlin ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Chemical Vapor ◽  
Organic Chemical ◽  
Height Distribution ◽  
Force Microscopy ◽  
Self Organized ◽  
Density Control ◽  
Atomic Force ◽  
Transmission Electron ◽  
Metal Organic

AbstractWe investigated structural and emission properties of self-organized InP/GaInP quantum dots (QD) grown by metal organic chemical vapor deposition using an amount of deposited In from 7 to 2 monolayers (ML). In the uncapped samples, using atomic force microscopy (AFM), we observed lateral sizes of 100–200 nm, together with a bimodal height distribution having maxima at ∼5 and ∼15 nm, which we denoted as QDs of type A and B, respectively; and reduction of the density of the type-B dots from 4.4 to 1.6 μm^–2. The reduction of the density of B-type dots were observed also using transmission electron microscopy of the capped samples. Using single dot low-temperature photoluminescence (PL) spectroscopy we demonstrated effects of Wigner localization for the electrons accumulated in these dots.

Fabrication and Characterization of Stacked Self-Assembled In0.5Ga0.5As/GaAs Quantum Dots Grown by MOCVD

2014 ◽  
Vol 896 ◽  
pp. 215-218
Author(s):  
Didik Aryanto ◽  
Zulkafli Othaman ◽  
A. Khamim Ismail
Keyword(s):  
Quantum Dots ◽  
Chemical Vapor ◽  
Organic Chemical ◽  
X Ray Diffraction ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron ◽  
Metal Organic ◽  
Self Assembled

Stacked self-assembled In0.5Ga0.5As/GaAs quantum dots (QDs) were grown using metal organic chemical vapor deposition (MOCVD). Atomic force microscopy (AFM), transmission electron microscopy (TEM) and high resolution X-ray diffraction (HR-XDR) show the effects of stacking on morphology and structure of QDs. Strains due to the buried QDs affect the shape and alignment of the successive layers. Capping of these QDs also determine the quality of the top most QDs structure.

Growth of crack-free GaN on AlN quantum dots on Si(111)substrates by MOCVD

2003 ◽  
Vol 798 ◽  
Author(s):  
W. H. Sun ◽  
J. L. Chen ◽  
L. S. Wang ◽  
S. J. Chua
Keyword(s):  
Quantum Dots ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Optical Microscope ◽  
X Ray Diffraction ◽  
X Ray ◽  
Force Microscopy ◽  
Transmission Electron ◽  
Pressure Chemical ◽  
Aln Buffer

AlN self-assembled quantum dots (QDs) with high density of ∼ 4.4 × 1010/cm2 on Si(111) substrates have been grown by low-pressure chemical vapor deposition under a very low V/III ratio of 350. We found that using AlN-QD/AlN buffer two-inch GaN epilayers without cracks were grown, indicating the underlying quantum dots play a crucial role in relaxing the stain of GaN epilayer. The quality and morphology were investigated by atom force microscopy, transmission electron microscopy, X-ray diffraction and optical microscope.

A Comparative Study of the Synthesis of Carbon Nanotubes Using Ni and Fe as Catalyst

2009 ◽  
Vol 67 ◽  
pp. 89-94 ◽  
Author(s):  
Joydip Sengupta ◽  
Sovan Kumar Panda ◽  
Chacko Jacob
Keyword(s):  
Electron Microscopy ◽  
Carbon Nanotubes ◽  
Chemical Vapor ◽  
X Ray Diffraction ◽  
Raman Spectroscopic ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron ◽  
Pressure Chemical ◽  
Synthesis Of Carbon Nanotubes

The effect of Fe and Ni catalysts on the synthesis of carbon nanotubes (CNTs) using atmospheric pressure chemical vapor deposition (APCVD) was investigated. Distribution of the catalyst particles over the Si substrate was analyzed by atomic force microscopy (AFM). Characterization by X-ray diffraction analysis (XRD), field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM) and Raman spectroscopic measurements over the grown species is reported. The study clearly shows that the catalyst strongly influences morphology and microstructure of the grown CNTs.

Effectiveness and Reliability of Metal Diffusion Barriers for Copper Interconnects

1995 ◽  
Vol 403 ◽  
Author(s):  
G. Bai ◽  
S. Wittenbrock ◽  
V. Ochoa ◽  
R. Villasol ◽  
C. Chiang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Vapor Deposition ◽  
Physical Vapor Deposition ◽  
Chemical Vapor ◽  
Diffusion Barriers ◽  
Copper Interconnects ◽  
Time To Failure ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron

AbstractCu has two advantages over Al for sub-quarter micron interconnect application: (1) higher conductivity and (2) improved electromigration reliability. However, Cu diffuses quickly in SiO2and Si, and must be encapsulated. Polycrystalline films of Physical Vapor Deposition (PVD) Ta, W, Mo, TiN, and Metal-Organo Chemical Vapor Deposition (MOCVD) TiN and Ti-Si-N have been evaluated as Cu diffusion barriers using electrically biased-thermal-stressing tests. Barrier effectiveness of these thin films were correlated with their physical properties from Atomic Force Microscopy (AFM), Transmission Electron Microscopy (TEM), Secondary Electron Microscopy (SEM), and Auger Electron Spectroscopy (AES) analysis. The barrier failure is dominated by “micro-defects” in the barrier film that serve as easy pathways for Cu diffusion. An ideal barrier system should be free of such micro-defects (e.g., amorphous Ti-Si-N and annealed Ta). The median-time-to-failure (MTTF) of a Ta barrier (30 nm) has been measured at different bias electrical fields and stressing temperatures, and the extrapolated MTTF of such a barrier is > 100 year at an operating condition of 200C and 0.1 MV/cm.

Ball-Milling Graphite Used for Synthesis of Biocompatible Blue Luminescent Graphene Quantum Dots

2021 ◽  
Vol 6 (2) ◽  
Author(s):  
Zhou J ◽  
◽  
Dong Y ◽  
Ma Y ◽  
Zhang T ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Ball Milling ◽  
Graphene Quantum Dots ◽  
Raw Material ◽  
Hydroxyl Groups ◽  
High Quality ◽  
Widespread Application ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron

Graphene Quantum Dots (GQDs) have been prepared by oxidationhydrothermal reaction, using ball-milling graphite as the starting materials. The prepared GQDs are endowed with excellent luminescence properties, with the optimum emission of 320nm. Blue photoluminescent emitted from the GQDs under ultraviolet light. The GQDs are ~3nm in width and 0.5~2 nm in thickness, revealed by high-resolution transmission electron microscopy and atomic force microscopy. In addition, Fourier transform infrared spectrum evidences the existence of carbonyl and hydroxyl groups, meaning GQDs can be dispersed in water easily and used in cellar imaging, and blue area inside L929 cells were clearly observed under the fluorescence microscope. Both low price of raw material and simple prepared method contribute to the high quality GQDs widespread application in future.

Ordering of InGaAs Quantum Dots Grown by Molecular Beam Epitaxy under As2 gas flux

2015 ◽  
Vol 1792 ◽  
Author(s):  
Mourad Benamara ◽  
Yuriy I. Mazur ◽  
Peter Lytvyn ◽  
Morgan E. Ware ◽  
Vitaliy Dorogan ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Quantum Dots ◽  
Atomic Force Microscopy ◽  
Molecular Beam Epitaxy ◽  
Large Scale ◽  
Molecular Beam ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron

ABSTRACTThe influence of the substrate temperature on the morphology and ordering of InGaAs quantum dots (QD), grown on GaAs (001) wafers by Molecular Beam Epitaxy (MBE) under As2 flux has been studied using Transmission Electron Microscopy (TEM), Atomic Force Microscopy (AFM) and Photoluminescence (PL) measurements. The experimental results show that lateral and vertical orderings occur for temperatures greater than 520°C and that QDs self-organize in a 6-fold symmetry network on (001) surface for T=555°C. Vertical orderings of asymmetric QDs, along directions a few degrees off [001], are observed on a large scale and their formation is discussed.

scholarly journals GROWTH AND PROPERTIES OF STACKED SELF-ASSEMBLED In0.5Ga0.5As QUANTUM DOTS

2012 ◽  
Vol 2 (1) ◽  
pp. 1
Author(s):  
Didik Aryanto ◽  
Zulkafli Othaman ◽  
Abd. Khamim Ismail
Keyword(s):  
Quantum Dots ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
The Self ◽  
Organic Chemical ◽  
Force Microscopy ◽  
Atomic Force ◽  
Metal Organic ◽  
Self Assembled ◽  
Organic Chemical Vapor Deposition

Self-assembled In0.5Ga0.5As quantum dots (QDs) were grown using metal-organic chemical vapor deposition (MOCVD) on GaAs (100) substrate with different number of stacking QDs layers. Surface study using atomic force microscopy (AFM) shows that surface morphology of the self-assembled QDs change with different number of stacking QDs layers caused by the previous QDs layers and the thickness of the GaAs spacer layers. PL measurement shows variation in the PL spectra as a function of number of stacking layers of In0.5Ga0.5As QDs. The PL peak positions blue-shifted from 1225 nm to 1095 nm and dramatically increase in intensity with increasing number of stacking QDs layers.

Near Field Optical Spectroscopy of GaN/AlN Quantum Dots

2004 ◽  
Vol 831 ◽  
Author(s):  
A. Neogi ◽  
B. P. Gorman ◽  
H. Morkoç ◽  
T. Kawazoe ◽  
M. Ohtsu ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Near Field ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron ◽  
Spacer Layer Thickness ◽  
Spacer Layer ◽  
Lateral Coupling ◽  
Self Assembled ◽  
Spectrally Resolved

ABSTRACTWe investigate the spatial distribution and emission properties of self-assembled GaN/AlN quantum dots. High-resolution transmission electron microscopy reveals near vertical correlation among the GaN dots due to a sufficiently thin AlN spacer layer thickness, which allows strain induced stacking. Scanning electron and atomic force microscopy show lateral coupling due to a surface roughness of ∼ 50–60 nm. Near-field photoluminescence in the illumination mode (both spatially and spectrally resolved) at 10 K revealed emission from individual dots, which exhibits size distribution of GaN dots from localized sites in the stacked nanostructure. Strong spatial localization of the excitons is observed in GaN quantum dots formed at the tip of self-assembled hexagonal pyramid shapes with six [101 1] facets.

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