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Quantum optics of a quantum dot embedded in a photonic crystal cavity
, Article Photonic Crystal Materials and Devices VII, San Jose, CA, 21 January 2008 through 23 January 2008 ; Volume 6901 , 2008 ; 0277786X (ISSN); 9780819470768 (ISBN) ; Khorasani, S ; Atabaki, A. H ; Adibi, A ; Sharif University of Technology
2008
Abstract
In this paper we analyze a disk-like quantum dot embedded in an engineered two-dimensional (2D) photonic crystal cavity as an artificial atom. In this quantum dot electron and hole form an exciton where photon and electron-hole bound state can interact. Within the engineered electromagnetic vacuum of the PBG material, the exciton can emit and reabsorb a photon. If the exciton energy lies near the photonic band gap edge the exciton level splits into two levels. This is similar to the interaction of field and an atom in a high Q cavity. Here excitonic states are evaluated taking in to account the band mixing for holes. Also energy associated with dressed exction is evaluated
Radial basis function-artificial neural network (RBF-ANN) for simultaneous fluorescent determination of cysteine enantiomers in mixtures
, Article Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy ; Volume 261 , 2021 ; 13861425 (ISSN) ; Reza Hormozi Nezhad, M ; Abdollahi, H ; Sharif University of Technology
Elsevier B.V
2021
Abstract
The determination of chiral compounds is critically important in chemical and pharmaceutical sciences. Cysteine amino acid is one of the important chiral compounds where each enantiomer (L and D) has different effects on fundamental physiological processes. The unique optical properties of nanoparticles make them a suitable probe for the determination of different analytes. In this work, the water-soluble thioglycolic acid (TGA)-capped cadmium-telluride (CdTe) quantum dots (QDs) were applied as optical nanoprobe for the simultaneous determination of cysteine enantiomers. The difference in the kinetics of the interactions between L- and D-cysteine with CdTe QDs is used for multivariate...
Fabrication of a sensitive colorimetric nanosensor for determination of cysteine in human serum and urine samples based on magnetic-sulfur, nitrogen graphene quantum dots as a selective platform and Au nanoparticles
, Article Talanta ; Volume 226 , 2021 ; 00399140 (ISSN) ; Dadfarnia, S ; Haji Shabani, A. M ; Kazemi, E ; Pedrini, A ; Verucchi, R ; Sharif University of Technology
Elsevier B.V
2021
Abstract
A novel colorimetric nanosensor is reported for the selective and sensitive determination of cysteine using magnetic-sulfur, nitrogen graphene quantum dots (Fe3O4/S, N-GQDs), and gold nanoparticles (Au NPs). Thus, S, N-GQDs was firstly immobilized on Fe3O4 nanoparticles through its magnetization in the presence of Fe3+ in the alkali solution. The prepared Fe3O4/S, N-GQDs were dispersed in cysteine solution resulting in its quick adsorption on the surface of the Fe3O4/S, N-GQDs through hydrogen bonding interaction. Then, Au NPs solution was added to this mixture that after a short time, the color of Au NPs changed from red to blue, the intensity of surface plasmon resonance peak of Au NPs at...
Fabrication of a sensitive colorimetric nanosensor for determination of cysteine in human serum and urine samples based on magnetic-sulfur, nitrogen graphene quantum dots as a selective platform and Au nanoparticles
, Article Talanta ; Volume 226 , 2021 ; 00399140 (ISSN) ; Dadfarnia, S ; Haji Shabani, A. M ; Kazemi, E ; Pedrini, A ; Verucchi, R ; Sharif University of Technology
Elsevier B.V
2021
Abstract
A novel colorimetric nanosensor is reported for the selective and sensitive determination of cysteine using magnetic-sulfur, nitrogen graphene quantum dots (Fe3O4/S, N-GQDs), and gold nanoparticles (Au NPs). Thus, S, N-GQDs was firstly immobilized on Fe3O4 nanoparticles through its magnetization in the presence of Fe3+ in the alkali solution. The prepared Fe3O4/S, N-GQDs were dispersed in cysteine solution resulting in its quick adsorption on the surface of the Fe3O4/S, N-GQDs through hydrogen bonding interaction. Then, Au NPs solution was added to this mixture that after a short time, the color of Au NPs changed from red to blue, the intensity of surface plasmon resonance peak of Au NPs at...
From continuous to quantized charging phenomena in few nanocrystals MOS structures
, Article 11th International Autumn Meeting on Gettering and Defect Engineering in Semiconductor Technlogy, GADEST 2005, Giens, 25 September 2005 through 30 September 2005 ; Volume 108-109 , 2005 , Pages 25-32 ; 10120394 (ISSN); 3908451132 (ISBN); 9783908451136 (ISBN) ; Shalchian, M ; Grisolia, J ; Bonafos, C ; Atarodi, S. M ; Claverie, A ; Sharif University of Technology
Trans Tech Publications Ltd
2005
Abstract
In this paper, we present a study on the contribution of silicon nanocrystals to the electrical transport characteristics of large (100 μm × 100 μm) and small (100 nm × 100 nm) metaloxide-semiconductor (MOS) capacitors at room temperature. A layer of silicon nanocrystals is synthesized within the oxide of these capacitors by ultra-low energy ion implantation and annealing. Several features including negative differential resistance (NDR), sharp current peaks and random telegraph signal (RTS) are demonstrated in the current-voltage and current-time characteristics of these capacitors. These features have been associated to charge storage in silicon nanocrystals and to the resulting Coulomb...
Determination of spermine and spermidine in meat with a ratiometric fluorescence nanoprobe and a combinational logic gate
, Article Food Chemistry ; Volume 384 , 2022 ; 03088146 (ISSN) ; Bigdeli, A ; Hormozi Nezhad, M. R ; Sharif University of Technology
Elsevier Ltd
2022
Abstract
A ratiometric fluorescent nanoprobe is developed with a wide color variation for visual determination of spermine (SP) and spermidine (SD) in meat samples. The green emission provided from the combination of yellow emissive quantum dots and blue emissive carbon dots turns into pink when SP or SD are present. The results show that the developed sensor has good linearity in the range of 0.5–10 and 0.5–80 µM for SP and SD and suitable detection limits were achieved including 0.2 and 2.1 µM for SP and SD. The probe was highly selective in the presence of amino acids and other biogenic amines. RGB indices were extracted to build a combinational logic gate for visual and simultaneous detection of...
Graphene/PbS as a novel counter electrode for quantum dot sensitized solar cells
, Article ACS Photonics ; Vol. 1, issue. 4 , March , 2014 , pp. 323-330 ; ISSN: 23304022 ; Samadpour, M ; Esfandiar, A ; Iraji Zad, A ; Sharif University of Technology
Abstract
PbS nanoparticles were in situ deposited on graphene sheets by a successive ionic liquid adsorption and reaction method to prepare a graphene/PbS composite counter electrode for CdS/CdSe quantum dot sensitized solar cells (QDSCs). Under 1 sun illumination, the cells with graphene/PbS counter electrodes (CEs) show a maximum energy conversion efficiency of 2.63%, which is remarkably higher than that of those employing PbS (1.28%) or graphene (0.23%) CEs. Electrochemical impedance spectroscopy analysis shows that graphene/PbS composite counter electrodes have lower charge-transfer resistance at the interface of the CE and the polysulfide redox electrolyte, compared to those cells with PbS and...
Small signal circuit modeling for semiconductor self-assembled quantum dot laser
, Article Optical Engineering ; Volume 50, Issue 3 , 2011 ; 00913286 (ISSN) ; Faez, R ; Sharif University of Technology
Abstract
In this paper, for the first time, we present a small signal circuit model of InGaAs/GaAs self-assembled quantum dot (QD) laser, based on the standard rate equations. By using the presented model, modulation response of QD laser is investigated. The simulation results show that retarded carrier relaxation due to phonon bottleneck degrades the modulation and impulse responses of a QD laser. It is shown that modulation bandwidth is increased with larger inhomogeneous broadening. Also, our model describes the effects of carrier recombinations inside and outside of a QD region, on the modulation response behavior
A new structure to increase the photostability of CdTe quantum dot sensitized solar cells
, Article Journal of Physics D: Applied Physics ; Volume 44, Issue 4 , January , 2011 ; 00223727 (ISSN) ; Iraji zad, A ; Taghavinia, N ; Molaei, M ; Sharif University of Technology
2011
Abstract
In this paper a new cell structure is introduced to reduce the rate of CdTe corrosion in quantum dot sensitized solar cells (QDSSCs) using I -/I- 3 electrolyte. In this cell, one electrode is a titania nanorod that was sensitized with CdTe quantum dots as the working electrode. A thin gold layer is sputtered on the electrode to act as a protective layer against the I-/I- 3 corrosive electrolyte and to passivate the CdTe surface traps which are the main recombination centres in a QDSSC. In addition, a Schottky barrier formed at the interface of Au and CdTe prevents direct electron recombination from the CdTe conduction band with I- 3 ions. The mechanism of charge transfer and quantum dot...
Surface engineering of pbs colloidal quantum dots using atomic passivation for photovoltaic applications
, Article 8th International Conference on Materials for Advanced Technologies, 28 June 2015 through 3 July 2015 ; Volume 139 , 2016 , Pages 117-122 ; 18777058 (ISSN) ; Sharif University of Technology
Elsevier Ltd
Abstract
Solution-processed quantum dots (QDs) have attracted significant attention for the low-cost fabrication of optoelectronic devices. Here, we synthesized PbS QDs via hot injection method and passivated the trap states by using short thiols and dopant elements for photovoltaic application. In order to study the effect of dopants on photovoltaic application, PbS QDs were doped by using three different cations: Cadmium, Calcium, and Zinc. We utilized Time resolvel Photoluminescence measurement to study the carriers lifetime for different samples and found that the carriers life time increases ∼80% by using Cd as a dopant compared with undoped sample. In addition, the results of J-V measurement...
Efficient design of a coplanar adder/subtractor in quantum-dot cellular automata
, Article 9th UKSim-AMSS IEEE European Modelling Symposium on Computer Modelling and Simulation, EMS 2015, 6 October 2015 through 8 October 2016 ; 2015 , Pages 456-461 ; 9781509002061 (ISBN) ; Karimpour, M ; Sarayloo, M ; Romero G ; Orsoni A ; Al-Dabass D ; Pantelous A ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2015
Abstract
Scaling of CMOS devices being aggressively decreasing by reduce of transistor dimensions. However, such level of integration leads to many physical limit and transistors cannot get much smaller than their current size. Quantum-dot Cellular Automate is a novel technology which significantly reduces physical limit of CMOS devices implementation, thus, it can be an appropriate candidate to be substituted for CMOS technology. In addition to high integration density of QCA circuits, other unique specifications such as high speed and low power consumption encourage researchers to utilize this technology instead of CMOS technology. In this paper, a new layout of XOR gate is presented in QCA...
Synthesis, properties and biomedical applications of carbon-based quantum dots: an updated review
, Article Biomedicine and Pharmacotherapy ; Volume 87 , 2017 , Pages 209-222 ; 07533322 (ISSN) ; Negahdari, B ; Eatemadi, A ; Sharif University of Technology
Elsevier Masson SAS
2017
Abstract
Carbon-based quantum dots (CQDs) are a newly developed class of carbon nano-materials that have attracted much interest and attention as promising competitors to already available semiconductor quantum dots owing to their un-comparable and unique properties. In addition, controllability of CQDs unique physiochemical properties is as a result of their surface passivation and functionalization. This is an update article (between 2013 and 2016) on the recent progress, characteristics and synthesis methods of CQDs and different advantages in varieties of applications. © 2017 Elsevier Masson SAS
High speed and low cost synchronous counter design in quantum-dot cellular automata
, Article Microelectronics Journal ; Volume 73 , March , 2018 , Pages 1-11 ; 00262692 (ISSN) ; Abedi, D ; Yoosefi, E ; Karimpour, M ; Sharif University of Technology
Elsevier Ltd
2018
Abstract
Quantum-dot Cellular Automata (QCA) is a very interesting nano-scale technology. Extremely small feature size and ultra-low power consumption are the most important features of QCA compared to CMOS. Counters are considered as one of the most fundamental components in sequential circuits. Previous QCA synchronous counters (QSCs) have been designed and simulated using two methods. In the first method, QSCs utilize direct mapping flip-flop designs in CMOS technology to QCA. In the second method, QSCs are designed with the inherent capability of QCA technology. Despite being attractive, mentioned approaches have constraints (i.e. long wire length and area issues). In this brief, design and...
An inhomogeneous theoretical model for analysis of PbSe quantum-dot-doped fiber amplifier
, Article Optics Communications ; Volume 282, Issue 22 , 2009 , Pages 4449-4454 ; 00304018 (ISSN) ; Rooholamini, H ; Rahimi, L ; Askari, A. A ; Sharif University of Technology
2009
Abstract
Optical fiber doped with lead salts quantum dots (QDs) of different radii, has previously been proposed as a wide-band amplifier in the optical communication range. The emission and absorption spectra of QDs are size-dependent. Optical fiber amplifier doped with QDs of different sizes is an inhomogeneous gain medium. This inhomogeneity is the principle of operation of wide-band quantum-dot-doped fiber amplifiers (QDFAs). To study the effects of inhomogeneity such as spectral hole burning on the amplifier behavior, a fiber amplifier with an arbitrary size distribution of QDs is taken into consideration. The light propagation equations and rate equations for the inhomogeneous medium are...
Oxygen plasma-induced p-type doping improves performance and stability of PbS quantum dot solar cells
, Article ACS Applied Materials and Interfaces ; Volume 11, Issue 29 , 2019 , Pages 26047-26052 ; 19448244 (ISSN) ; Tavakoli, R ; Yadav, P ; Prochowicz, D ; Saliba, M ; Tavakoli, M. M ; Sharif University of Technology
American Chemical Society
2019
Abstract
PbS quantum dots (QDs) have been extensively studied for photovoltaic applications, thanks to their facile and low-cost fabrication processing and interesting physical properties such as size dependent and tunable band gap. However, the performance of PbS QD-based solar cells is highly sensitive to the humidity level in the ambient air, which is a serious obstacle toward its practical applications. Although it has been previously revealed that oxygen doping of the hole transporting layer can mitigate the cause of this issue, the suggested methods to recover the device performance are time-consuming and relatively costly. Here, we report a low-power oxygen plasma treatment as a rapid and...
Photovoltaic performance and electrochemical impedance spectroscopy analysis of CdS/CdSe-sensitized solar cell based on surfactant-modified ZnS treatment
, Article Applied Physics A: Materials Science and Processing ; Volume 126, Issue 6 , 2020 ; Dehghani, M ; Parand, P ; Natagh Najafi, M ; Parvazian, E ; Sharif University of Technology
Springer
2020
Abstract
Among the various approaches, ZnS treatment is the most convenient method for reducing the charge recombination in quantum dot-sensitized solar cells (QDSSCs). Here an improved method of ZnS treatment is explained for efficiency enhancement in QDSSCs. To get to the goal of device performance improvement, it is essential to have a uniform deposited layer. We utilized Triton X-100 (TX-100) as a surfactant to the convenient aqueous precursors during ZnS deposition by successive ionic layer adsorption and reaction method. It helps to decrease in contact angle and increase in wettability of the aqueous precursor and results in a more uniform deposited layer. The effect of modified ZnS treatment...
Investigating the shape evolution mechanism of CdSe quantum dots by chemometrics analysis of spectrophotometry data
, Article Journal of Physical Chemistry C ; Volume 112, Issue 47 , 2008 , Pages 18321-18324 ; 19327447 (ISSN) ; Hormozi Nezhad, M. R ; Sharif University of Technology
2008
Abstract
The study on the mechanism of the shape evolution of nanocrystaline particles is an important and emerging field, which is applicable in the shaped control synthesis of nanoparticles. As an alternative to transmittance electron microscopy (TEM), which is already used in the study of nanoparticles, in this article a simple spectrophotometric method has been proposed utilizing the advantages of chemometrics methods in analyzing overlapped and complex spectral data. The evolutionary visible absorbance data of CdSe quantum dots through particle formation were analyzed by factor analysis, evolving factor analysis, and multivariate curve resolution-alternative least-squares analysis, by which four...
A ratiometric fluorescence nanoprobe using CdTe QDs for fast detection of carbaryl insecticide in apple
, Article Talanta ; Volume 221 , 2021 ; 00399140 (ISSN) ; Fahimi Kashani, N ; Hormozi nezhad, M. R ; Sharif University of Technology
Elsevier B.V
2021
Abstract
In this study, a novel, simple and sensitive ratiometric fluorescence method is presented for the detection of very low quantities of the carbaryl in Iranian apple using cadmium telluride quantum dots (CdTe QDs) nanoprobe. The principle of the proposed strategy relies on the rapid hydrolysis of the carbaryl under an alkaline condition and production of the 1-naphthol with a blue emission at 470 nm. Besides, using the CdTe QDs with a yellow emission at 580 nm, as a reference, improves the visual tracking of carbaryl through changes in color tonality. The herein described methodology is applied for enzyme-free visual detection of carbaryl with satisfactory results in the presence of other...
Hybrid ultrasound-activated nanoparticles based on graphene quantum dots for cancer treatment
, Article International Journal of Pharmaceutics ; Volume 629 , 2022 ; 03785173 (ISSN) ; Sabzevari, O ; Simchi, A ; Sharif University of Technology
Elsevier B.V
2022
Abstract
Theranostic liposomes have recently found a broad range of applications in nanomedicine due to stability, the high solubility of biomacromolecules, bioavailability, efficacy, and low adverse effects. However, the limitations of liposomes concerning the short systemic circulation in the body, limited controllability of the release rate, and the inability of in vivo imaging remain challenging. Herein, the development of novel hybrid ultrasound-activated piezoelectric nanoparticles based on a hybrid liposome nanocarrier composed of poly(vinylidene fluoride‐trifluoroethylene), graphene quantum dots (GQDs), and Silibinin (a hydrophobic drug) is presented. The hybrid nanoparticles are an...
A comprehensive review on planar boron nitride nanomaterials: From 2D nanosheets towards 0D quantum dots
, Article Progress in Materials Science ; Volume 124 , 2022 ; 00796425 (ISSN) ; Alem, S. A. A ; Hasanzadeh Azar, M ; Shayeganfar, F ; Manning, M. I ; Hatamie, A ; Pakdel, A ; Simchi, A ; Sharif University of Technology
Elsevier Ltd
2022
Abstract
Moving from two-dimensional hexagonal boron nitride (2D h-BN) flatlands towards their quantum sized zero-dimensional (0D) islands, as the newest member of the h-BN family, has recently opened up novel research areas due to the emergence of unique optical and physicochemical properties, excellent thermal and chemical stability, and desirable biocompatibility. This review elaborates on the fundamental properties of 2D and 0D h-BN nanomaterials and covers the latest progress in the fabrication and applications of BN nanosheets (BNNSs) and quantum dots (BNQDs). Initially, the transformation of properties in h-BN nanomaterials is discussed when moving from the 2D realm towards the 0D quantum...