Modified two-dimensional to three-dimensional growth transition process in multistacked self-organized quantum dots

2001 ◽  
Vol 63 (15) ◽  
Author(s):  
Catherine Priester
Keyword(s):  
Quantum Dots ◽  
Three Dimensional ◽  
Transition Process ◽  
Two Dimensional ◽  
Self Organized ◽  
Dimensional Growth

Control of the two-dimensional–three-dimensional transition of self-organized CdSe/ZnSe quantum dots

2005 ◽  
Vol 16 (8) ◽  
pp. 1116-1118 ◽  
Author(s):  
I C Robin ◽  
R André ◽  
H Mariette ◽  
S Tatarenko ◽  
Le Si Dang ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Three Dimensional ◽  
Two Dimensional ◽  
Self Organized

Numerical simulation of boundary-layer transition and transition control

1989 ◽  
Vol 199 ◽  
pp. 403-440 ◽  
Author(s):  
E. Laurien ◽  
L. Kleiser
Keyword(s):  
Boundary Layer ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Transition Process ◽  
Numerical Results ◽  
Boundary Layer Transition ◽  
Two Dimensional ◽  
Layer Transition ◽  
Longitudinal Vortices ◽  
Tollmien Schlichting

The laminar-turbulent transition process in a parallel boundary-layer with Blasius profile is simulated by numerical integration of the three-dimensional incompressible Navier-Stokes equations using a spectral method. The model of spatially periodic disturbances developing in time is used. Both the classical Klebanoff-type and the subharmonic type of transition are simulated. Maps of the three-dimensional velocity and vorticity fields and visualizations by integrated fluid markers are obtained. The numerical results are compared with experimental measurements and flow visualizations by other authors. Good qualitative and quantitative agreement is found at corresponding stages of development up to the one-spike stage. After the appearance of two-dimensional Tollmien-Schlichting waves of sufficiently large amplitude an increasing three-dimensionality is observed. In particular, a peak-valley structure of the velocity fluctuations, mean longitudinal vortices and sharp spike-like instantaneous velocity signals are formed. The flow field is dominated by a three-dimensional horseshoe vortex system connected with free high-shear layers. Visualizations by time-lines show the formation of A-structures. Our numerical results connect various observations obtained with different experimental techniques. The initial three-dimensional steps of the transition process are consistent with the linear theory of secondary instability. In the later stages nonlinear interactions of the disturbance modes and the production of higher harmonics are essential.We also study the control of transition by local two-dimensional suction and blowing at the wall. It is shown that transition can be delayed or accelerated by superposing disturbances which are out of phase or in phase with oncoming Tollmien-Schlichting instability waves, respectively. Control is only effective if applied at an early, two-dimensional stage of transition. Mean longitudinal vortices remain even after successful control of the fluctuations.

Sensitivity To Disorder Of Graphene-Like Lattices Of Quantum Dots And Antidots In Two-Dimensional Electron Gas

2016 ◽  
Vol 11 (1) ◽  
pp. 80-87
Author(s):  
Olga Tkachenko ◽  
Vitaliy Tkachenko
Keyword(s):  
Quantum Dots ◽  
Electron Gas ◽  
Three Dimensional ◽  
Two Dimensional ◽  
Dimensional Electron ◽  
Two Dimensional Electron Gas ◽  
Semiconductor Structures ◽  
Dimensional Electron Gas ◽  
Artificial Graphene ◽  
Electronic Channels

We compare three-dimensional electrostatics of semiconductor structures with graphene-like lattices of quantum dots and antidots formed in the plane of the two dimensional electron gas. With lattice constant fixed, the shape of the potential may be tuned so that both lattices have minband spectrum where the second Dirac feature is pronounced and not overlaid by the other states. We show that the lattice of quantum dots is more sensitive to fabrication imperfections, because sources of the disorder are located directly above the electronic channels. Thus the lattices of antidots should be preferred semiconductor artificial graphene candidates.

Crystallization Time Dependence of Nanohybrid Shish-Kebab Structure in HDPE/PA66 Nanofibers Composites via Solution Crystallization

2011 ◽  
Vol 110-116 ◽  
pp. 3786-3790
Author(s):  
Wen Juan Han ◽  
Guo Qiang Zheng ◽  
Yan Yan Liang ◽  
Chun Tai Liu ◽  
Chang Yu Shen
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Time Dependence ◽  
Isothermal Crystallization ◽  
Three Dimensional ◽  
Crystallization Time ◽  
Two Dimensional ◽  
Solution Crystallization ◽  
Dimensional Growth ◽  
Scanning Electron

In this study, PA66 nanofibers were successfully solution electrospun. The crystalline morphological features of HDPE solution induced by nanofibers were investigated by scanning electron microscopy (SEM). Nanohybrid shish-kebab (NHSK) can be formed in HDPE solution via isothermal crystallization, in which PA66 nanofibers serve as shish and HDPE lamellae act as kebabs surrounding the nanofibers periodically. Additionally, crystallization time has significant effect on the structure of HDPE kebab in NHSK, i.e., as crystallization time increases, the size of the kebab increases and the crystals decorated on PA66 nanofibers exhibit a three-dimensional growth (i.e., aggregate of crystallites) rather than a two-dimensional one (i.e., disc-like lamellae normal to the axis of nanofiber).

From two-dimensional to three-dimensional quantum dots

2002 ◽  
Vol 13 (2-4) ◽  
pp. 638-641 ◽  
Author(s):  
S. Lindemann ◽  
T. Ihn ◽  
T. Heinzel ◽  
K. Ensslin ◽  
K. Maranowski ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Three Dimensional ◽  
Two Dimensional

Photoluminescence study of the crossover from two‐dimensional to three‐dimensional growth for Ge on Si(100)

1995 ◽  
Vol 67 (9) ◽  
pp. 1292-1294 ◽  
Author(s):  
P. Schittenhelm ◽  
M. Gail ◽  
J. Brunner ◽  
J. F. Nützel ◽  
G. Abstreiter
Keyword(s):  
Three Dimensional ◽  
Two Dimensional ◽  
Photoluminescence Study ◽  
Dimensional Growth
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