نتایج جستجو برای: and quantum dots

تعداد نتایج: 16908529  

Journal: :Biochemical and biophysical research communications 2006
William W Yu Emmanuel Chang Rebekah Drezek Vicki L Colvin

Semiconductor nanocrystals are 1-10nm inorganic particles with unique size-dependent optical and electrical properties due to quantum confinement (so they are also called quantum dots). Quantum dots are new types of fluorescent materials for biological labeling with high quantum efficiency, long-term photostability, narrow emission, and continuous absorption spectra. Here, we discuss the recent...

ژورنال: ارمغان دانش 2020

Background and aim: Cell-therapy is an important science because of using to treatment of critical-sized bone defects. Recent studies in this field suggest that human endometrial derived stem cells can be a great source. On the other hand, graphene and its derivatives, mainly graphene quantum dots (GQDs) have recently attracted much attention as effective factors in differentiating stem cells t...

2002
A. J. Chiquito J. C. Galzerani

An electrostatic model was presented for the calculation of the capacitance-voltage characteristics of a semiconductor structure where quantum dots were embedded. The model was based on the linear coupling between the contributions of the quantum dots and the bulk host. We further applied this model to an InAs/GaAs self-assembled quantum dots system. The calculated capacitance was found in good...

2001
Vidar Gudmundsson Andrei Manolescu Detlef Heitmann

We explore the structural changes in charge the density and the electron configuration of quantum dots caused by the presence of other dots in an array, and the interaction of neighboring dots. We discuss what recent measurements and calculation of the far-infrared absorption reveal about almost isolated quantum dots and investigate some aspects of the complex transition from isolated dots to d...

ژورنال: فیزیک کاربردی 2019

ضخامت لایۀ­ نقاط کوانتومی و نیمه­رسانای شفاف با شکاف بزرگ، میزان ناخالصی لایۀ نقاط کوانتومیو نوع فلز آند از جمله عوامل تأثیرگذار بر بازدهِ سلول­های خورشیدی نقطۀ کوانتومی ناهمجنس (HQDSC) می­باشند. در این مقاله با استفاده از نرم­افزار کامسول نسخه 4/5، ابتدا سلولی شامل یک لایه از نقاط کوانتومی سولفید سرب (PbS) پوشیده از لیگاندهای کوتاه و یک لایه نیمه­رسانای اکسید روی (ZnO) و آندی از جنس طلا شبیه­سا...

2001
Koji Ishibashi Yoshinobu Aoyagi

We review our experimental study on the electron transport in quantum dots, formed in the two-dimensional electron gas in GaAs/AlGaAs heterostructures. Single electron transport with well-resolved zero-dimensional energy levels is described for both single and coupled quantum dots. Effects of microwave irradiation are also studied, and photon assisted tunneling was observed between two discrete...

2005
J. Požela

A model that explains the unusual characteristics of the AlGaAs/GaAs modulation-doped field-effect transistor (MODFET) with InAs quantum dots incorporated in the GaAs channel is presented. It is shown that the negative charge of electrons confined in quantum dots decreases the threshold gate–drain voltage at which the channel is fully depleted. This provides an impact ionization of quantum dots...

1996
K. Ziegler

A two-dimensional array of quantum dots in a magnetic field is considered. The electrons in the quantum dots are described as unitary random matrix ensembles. The strength of the magnetic field is such that there is half a flux quantum per plaquette. This model exhibits the Integer Quantum Hall Effect. For N electronic states per quantum dot the limit N → ∞ can be solved by a saddle point integ...

1997
M Switkes A G Huibers C M Marcus K Campman A C Gossard

We report transport measurements as a function of bias in open semiconductor quantum dots. These measurements are well described by an effective electron temperature derived from Joule heating at the point contacts and cooling by Wiedemann-Franz out-diffusion of thermal electrons. Using this model, we propose and analyze a quantum dot based sensor which measures absolute magnetic field at micro...

Journal: :international journal of nano dimension 0
a. pourahmad department of chemistry, guilan science and research branch, islamic azad university, guilan, iran.

we report the growth by ion exchange synthesis of zns nanoparticles in mcm-41 matrices using zn (ch3coo)2 and na2s starting sources. the final product (zns/mcm-41) was characterized by x-ray diffraction (xrd) pattern, transmission electron microscopy (tem), scanning electron microscopy (sem), infrared spectrometry (ir) and uv-vis spectroscopy. its crystalline structure and morphology was studie...

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