Fluorescence intermittency of silicon nanocrystals and other quantum dots: A unified two-dimensional diffusion-controlled reaction model

2007 ◽  
Vol 127 (11) ◽  
pp. 111105 ◽  
Author(s):  
Jau Tang
Keyword(s):  
Quantum Dots ◽  
Silicon Nanocrystals ◽  
Reaction Model ◽  
Two Dimensional ◽  
Dimensional Diffusion ◽  
Diffusion Controlled ◽  
Fluorescence Intermittency ◽  
Diffusion Controlled Reaction

Steady state in two-dimensional diffusion-controlled reactions

1997 ◽  
Vol 89 (1-2) ◽  
pp. 369-377
Author(s):  
C. A. Condat ◽  
G. J. Sibona ◽  
C. E. Budde
Keyword(s):  
Steady State ◽  
Two Dimensional ◽  
Dimensional Diffusion ◽  
Diffusion Controlled

Monodisperse and size-tunable PbS colloidal quantum dots via heterogeneous precursors

2017 ◽  
Vol 5 (8) ◽  
pp. 2182-2187 ◽  
Author(s):  
Samuel Chan ◽  
Maning Liu ◽  
Kay Latham ◽  
Mitsutaka Haruta ◽  
Hiroki Kurata ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Colloidal Quantum Dots ◽  
Diffusion Controlled ◽  
Diffusion Controlled Reaction

Monodisperse and size-tunable PbS QDs were synthesized via the diffusion controlled reaction of turbid suspensions of reactive N,N′-diphenylthiourea and PbCl2 precursors.

scholarly journals Temperature Activated Dimensionality Crossover in the Nucleation of Quantum Dots by Droplet Epitaxy on GaAs(111)A Vicinal Substrates

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Artur Tuktamyshev ◽  
Alexey Fedorov ◽  
Sergio Bietti ◽  
Shiro Tsukamoto ◽  
Stefano Sanguinetti
Keyword(s):  
Quantum Dots ◽  
Low Temperature ◽  
Droplet Epitaxy ◽  
One Dimension ◽  
Finite Width ◽  
Two Dimensional ◽  
Droplet Nucleation ◽  
Adatom Diffusion ◽  
Dimensional Diffusion ◽  
Droplet Density

Abstract A temperature activated crossover between two nucleation regimes is observed in the behavior of Ga droplet nucleation on vicinal GaAs(111)A substrates with a miscut of 2° towards $$(\bar{1}\bar{1}2)$$ ( 1 ¯ 1 ¯ 2 ) . At low temperature (<400 °C) the droplet density dependence on temperature and flux is compatible with droplet nucleation by two-dimensional diffusion. Increasing the temperature, a different regime is observed, whose scaling behavior is compatible with a reduction of the dimensionality of the nucleation regime from two to one dimension. We attribute such behavior to a presence of finite width terraces and a sizeable Ehrlich-Schwöbel barrier at the terrace edge, which hinders adatom diffusion in the direction perpendicular to the steps.

A Total-Concentration Fixed-Grid Method for Two-Dimensional Diffusion-Controlled Wet Chemical Etching

2005 ◽  
Author(s):  
P. Rath ◽  
J. C. Chai ◽  
H. Y. Zheng ◽  
Y. C. Lam ◽  
V. M. Murukeshan
Keyword(s):  
Chemical Etching ◽  
Total Concentration ◽  
Diffusion Problem ◽  
Two Dimensional ◽  
Concentration Method ◽  
Dimensional Diffusion ◽  
Diffusion Controlled ◽  
Grid Approach ◽  
Wet Chemical ◽  
Wet Chemical Etching

This article presents a total concentration method for two-dimensional wet chemical etching. The proposed procedure is a fixed-grid approach. It is analogous to the enthalpy method used for modeling melting/solidification problems. The governing equation is formulated using the total concentration of the etchant. It includes the reacted and the unreacted concentrations of the etchant. The proposed governing equation includes the interface condition. The reacted concentration is used to capture the etchant-substrate interface implicitly. Since the grids are fixed, a diffusion problem remains a diffusion problem unlike the moving grid approach where the diffusion problem becomes the convection-diffusion problem due to the mesh velocity. For demonstration purposes, the finite volume method is used to solve for the transient concentration distribution of etchant. In this article, two-dimensional diffusion-controlled wet chemical etching processes are modeled. The results obtained from the proposed total concentration method are compared with available “analytic” solutions and solutions from moving-grid approach.

Periodic Two-dimensional Arrays of Silicon Quantum Dots for Nanoscale Device Applications

2002 ◽  
Vol 737 ◽  
Author(s):  
Christopher C. Striemer ◽  
Rishikesh Krishnan ◽  
Qianghua Xie ◽  
Leonid Tsybeskov ◽  
Philippe M. Fauchet
Keyword(s):  
Quantum Dots ◽  
Silicon Nanocrystals ◽  
Nanocrystalline Silicon ◽  
Bottom Of The Pyramid ◽  
Two Dimensional ◽  
Silicon Nanocrystal ◽  
Silicon Nanoclusters ◽  
Silicon Quantum Dots ◽  
Nanoscale Device ◽  
Device Applications

ABSTRACTWe report a successful unification of standard lithographic approaches (top down), anisotropic etching of atomically smooth surfaces, and controlled crystallization of silicon quantum dots (bottom up) to produce silicon nanoclusters at desired locations. These results complement our previous demonstration of silicon nanocrystal uniformity in size, shape, and crystalline orientation in nanocrystalline silicon (nc-Si)/SiO2 superlattices, and could lead to practical applications of silicon nanocrystals in electronic devices. The goal of this study was to induce silicon nanocrystal nucleation at specific lateral sites in a continuous amorphous silicon (a-Si) film. Nearly all previous studies of silicon nanocrystals are based on films containing isolated nanocrystals with random lateral position and spacing. The ability to define precise two-dimensional arrays of quantum dots would allow each quantum dot to be contacted using standard photolithographic techniques, leading to practical device applications like high-density memories. In this work, a template substrate consisting of an array of pyramid-shaped holes in a (100) silicon wafer was formed using standard microfabrication techniques. The geometry of this substrate then influenced the crystallization of an a-Si/SiO2 superlattice that was deposited on it, resulting in preferential nucleation of silicon nanoclusters near the bottom of the pyramid holes. These clusters are clearly visible in transmission electron microscopy (TEM) images, while no clusters have been observed on the planar surface areas of the template. Possible explanations for this selective nucleation and future device structures will be discussed.

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