Fabrication using x-ray nanolithography and measurement of Coulomb blockade in a variable-sized quantum dot

1994 ◽  
Vol 12 (6) ◽  
pp. 3611 ◽  
Author(s):  
M. Burkhardt
Keyword(s):  
Quantum Dot ◽  
Coulomb Blockade ◽  
X Ray

The direct observation of charge separation dynamics in CdSe quantum dots/cobaloxime hybrids

2016 ◽  
Vol 18 (6) ◽  
pp. 4300-4303 ◽  
Author(s):  
J. Huang ◽  
Y. Tang ◽  
K. L. Mulfort ◽  
X. Zhang
Keyword(s):  
Quantum Dots ◽  
Quantum Dot ◽  
Charge Separation ◽  
Cdse Quantum Dots ◽  
X Ray ◽  
Molecular Catalyst ◽  
Cdse Quantum Dot ◽  
Photoinduced Charge Separation ◽  
X Ray Absorption ◽  
Photoinduced Charge

In this work, we investigated photoinduced charge separation dynamics in a CdSe quantum dot/cobaloxime molecular catalyst hybrid using the combination of transient optical (OTA) and X-ray absorption (XTA) spectroscopy.

KONDO EFFECT AND SPIN-CHARGE SEPARATION IN QUANTUM DOTS

2001 ◽  
Vol 15 (10n11) ◽  
pp. 1426-1442
Author(s):  
L. I. GLAZMAN ◽  
F. W. J. HEKKING ◽  
A. I. LARKIN
Keyword(s):  
Quantum Dot ◽  
Charge Separation ◽  
Coulomb Blockade ◽  
Kondo Effect ◽  
Broad Band ◽  
Single Mode ◽  
Kondo Temperature ◽  
Average Charge ◽  
Opposite Case ◽  
Anderson Impurity Model

The Kondo effect in a quantum dot is discussed. In the standard Coulomb blockade setting, tunneling between the dot and the leads is weak, the number of electrons in the dot is well-defined and discrete; the Kondo effect may be considered in the framework of the conventional one-level Anderson impurity model. It turns out however, that the Kondo temperature TK in the case of weak tunneling is extremely low. In the opposite case of almost reflectionless single-mode junctions connecting the dot to the leads, the average charge of the dot is not discrete. Surprisingly, its spin may remain quantized: s=1/2 or s=0, depending (periodically) on the gate voltage. Such a "spin-charge separation" occurs because, unlike an Anderson impurity, a quantum dot carries a broad-band, dense spectrum of discrete levels. In the doublet state, the Kondo effect develops with a significantly enhanced TK. Like in the weak-tunneling regime, the enhanced TK exhibits strong mesoscopic fluctuations. The statistics of the fluctuations is universal, and related to the Porter-Thomas statistics of the wave function fluctuations.

scholarly journals Structural characterization of self-assembled quantum dot structures by X-ray diffraction techniques

1997 ◽  
Vol 306 (2) ◽  
pp. 198-204 ◽  
Author(s):  
A.A. Darhuber ◽  
J. Stangl ◽  
V. Holy ◽  
G. Bauer ◽  
A. Krost ◽  
...  
Keyword(s):  
Quantum Dot ◽  
Structural Characterization ◽  
X Ray Diffraction ◽  
X Ray ◽  
Self Assembled

scholarly journals Coplanar and grazing incidence x-ray-diffraction investigation of self-organized SiGe quantum dot multilayers

1998 ◽  
Vol 58 (12) ◽  
pp. 7934-7943 ◽  
Author(s):  
V. Holý ◽  
A. A. Darhuber ◽  
J. Stangl ◽  
S. Zerlauth ◽  
F. Schäffler ◽  
...  
Keyword(s):  
Quantum Dot ◽  
Grazing Incidence ◽  
X Ray Diffraction ◽  
X Ray ◽  
Self Organized ◽  
Sige Quantum Dot

Characterization of Colloidal Quantum Dot Ligand Exchange by X-ray Photoelectron Spectroscopy

2013 ◽  
Vol 42 (5) ◽  
pp. 809-814 ◽  
Author(s):  
Ayomide Atewologun ◽  
Wangyao Ge ◽  
Adrienne D. Stiff-Roberts
Keyword(s):  
Quantum Dot ◽  
Photoelectron Spectroscopy ◽  
Ligand Exchange ◽  
X Ray ◽  
Colloidal Quantum Dot

Efficiency Enhancement by Insertion of ZnO Recombination Barrier Layer in CdS Quantum Dot-Sensitized Solar Cells

2021 ◽  
Vol 21 (7) ◽  
pp. 3800-3805
Author(s):  
Abdul Razzaq ◽  
Muhammad Zafar ◽  
Tahir Saif ◽  
Jun Young Lee ◽  
Jung Ki Park ◽  
...  
Keyword(s):  
Solar Cell ◽  
Quantum Dot ◽  
Barrier Layer ◽  
Open Circuit ◽  
X Ray Diffraction ◽  
Solar Cell Performance ◽  
X Ray ◽  
Cds Quantum Dot ◽  
Back Transfer ◽  
Photovoltaic Characteristics

In this investigation we report the formation of thin ZnO recombination barrier layer at TiO2/CdS interface aimed for the improvement in performance of CdS sensitized solar cell. The film was deposited upon nanocrystalline mesoporous TiO2 surface by following a simple chemical process and characterized, using UV-Visible spectroscopy, X-ray diffraction and electron dispersive X-ray measurements. The insertion of ZnO thin layer enhances the QDSC (Quantum dot sensitized solar cell) performance, contributed mainly by an increase in open circuit voltage (Voc) due to reduced electron back transfer from TiO2 conduction band. Moreover, the analysis of photovoltaic characteristics upon increasing the thickness of the ZnO film reveals that the ZnO recombination barrier layer with optimum thickness at porous TiO2/CdS interface proved to be an effective potential barrier for minimizing electron back recombination.

scholarly journals Improvement of Quantum Dot Light Emitting Device Characteristics by CdSe/ZnS Blended with HMDS (Hexamethyldisilazane)

2020 ◽  
Vol 10 (17) ◽  
pp. 6081
Author(s):  
Junekyun Park ◽  
Eunkyu Shin ◽  
Jongwoo Park ◽  
Yonghan Roh
Keyword(s):  
Quantum Dot ◽  
Photoelectron Spectroscopy ◽  
Surface Defects ◽  
Hole Transport ◽  
Transport Layer ◽  
Electron Transport Layer ◽  
Hole Transport Layer ◽  
Atmospheric Conditions ◽  
Light Emitting ◽  
X Ray

We demonstrated the way to improve the characteristics of quantum dot light emitting diodes (QD-LEDs) by adding a simple step to the conventional fabrication process. For instance, we can effectively deactivate the surface defects of quantum dot (QD) (e.g., CdSe/ZnS core-shell QDs in the current work) with the SiO bonds by simply mixing QDs with hexamethyldisilazane (HMDS) under atmospheric conditions. We observed the substantial improvement of device characteristics such that the current efficiency, the maximum luminance, and the QD lifetime were improved by 1.7–1.8 times, 15–18%, and nine times, respectively, by employing this process. Based on the experimental data (e.g., energy dispersive X-ray spectroscopy (EDX), and X-ray photoelectron spectroscopy (XPS)), we estimated that the growth of the SiOx on the surface of QDs is self-limited: the SiOx are effective to passivate the surface defects of QDs without deteriorating the intrinsic properties including the color-purity of QDs. Second, we proposed that the emission profiling study can lead us to the fundamental understanding of charge flow in each layer of QD-LEDs. Interestingly enough, many problems related to the charge-imbalance phenomenon were simply solved by selecting the combination of thicknesses of the hole transport layer (HTL) and the electron transport layer (ETL).

Electron Microscopy Analysis of CdSe-CdS Quantum Dot-in-Rods Coated Mimosa pudica Fibre

2016 ◽  
Vol 12 ◽  
pp. 79-87 ◽  
Author(s):  
Soumya Ranjan Patra ◽  
B. Mallick ◽  
S.K. Samal ◽  
S.C. Mishra ◽  
P. Pattojoshi ◽  
...  
Keyword(s):  
Quantum Dot ◽  
Detection System ◽  
Honeycomb Structure ◽  
Fluorescent Nanoparticles ◽  
Mimosa Pudica ◽  
X Ray ◽  
Quantum Size ◽  
Cds Quantum Dot ◽  
Electron Microscopy Analysis ◽  
Low X

Semiconducting polymer based X-ray detector design is quite interesting and challenging task for the researchers. Because of low X-ray attenuation of polymers, the device becomes insensitive. In the paper we report a way through the introduction of fluorescent nanoparticles to increase the X-ray detection probability.The Mimosa pudica fibre was coated with CdSe-CdS quantum dot-in-rods on the surface by chemical dipping processes. The fibre morphology and microstructure have been analysed by TEM and SEM techniques. The well-oriented CdSe-CdS quantum dot-in-rods have been observed in TEM with an aspect ratio (rod length ̸ rod diameter) of 28.7×3.5 nm and quantum yield 78% of a sharp emission peak at 545 nm. The CdSe-CdS quantum dot-in-rods coated M. pudica fibre, as observed in SEM, possesses a honeycomb structure of the nano-material. It is expected that the interaction between static-electric field of the fibre and the field produced by the above quantum particle causes to form a well-ordered honeycomb cover on the fibre of the surface. The goal of this study is to confirm the feasibility of the X-ray imaging detection system based on the quantum size effect on coated conducting fibre.

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