radiative cascades in semiconductor quantum dots

... II-VI semiconductors 38 2.3 TPA in strong confinement quantum dots 39 2.3.1 General information of TPA transition in quantum dots 40 2.3.2 TPA transition in quantum dots considering band mixing ... RELAXATION IN CdSe QUANTUM DOTS 70 4.1 Introduction 70 4.2 Synthesis and characterization of CdSe quantum dots 74 4.3 TPA coefficients in CdSe quantum dots 79 4.4 Auger process following TPA in CdSe quantum ... mentioned in the last section, semiconductor materials confined in one, two and three dimensions in the nano-scale are called quantum wells, quantum wires and quantum dots, respectively In quantum...

Ngày tải lên: 14/09/2015, 08:38

... constants In semiconductor nanomaterials, quantum confinement leads to electronic quantization with the level spacing increasing with decrease in size When the spacing between the low lying energy ... three-dimensional Schrodinger equation in cylindrical coordinates r ,  and z with the potential V (r )  for r  R and infinite otherwise In this case, independent solutions for the three coordinates can ... probe at 2.5 eV in a ns window……………………………….123 Figure 6.4 Quantized steps in quantum- confined Auger recombination in QDs……………125 Figure 6.5 Intensity dependent decay observed in Sample 2-1-2...

Ngày tải lên: 17/09/2015, 17:17

... innovative approaches for treating cancer: photodynamic therapy (PDT), and introduce quantum dots as a possible photosensitizer sensor Since quantum dots intrinsic property of giving off luminescent ... soluble CdHgTe quantum dots By using the quantum dots synthesized previously, we could obtain CdHgTe infrared emission quantum dots by the following method First dissolve Hg(ClO4)2·H2O into deionized ... shell, impeding the Hg ions from penetrating into the inner core of the CdTe quantum dots, which maintains higher luminescence intensity If we use the “multiple times” strategy, the much thinner layer...

Ngày tải lên: 28/04/2014, 15:48

... Strong coupling among semiconductor quantum dots induced by a metal nanoparticle Yong He and Ka-Di Zhu∗ Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), ... surface plasmon polaritons (SPP) in a metal nanoparticle (MNP) and the excitons in semiconductor quantum dots (SQDs) in an SQD-MNP coupled system We propose a quantum transformation method to ... Au MNP for revealing the coupling between two SQDs induced by SPP field, as shown in left inset of Figure The interaction between the two identical SQDs can be neglected safely in the absence of...

Ngày tải lên: 20/06/2014, 20:20

... Strong coupling among semiconductor quantum dots induced by a metal nanoparticle Yong He and Ka-Di Zhu∗ Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), ... surface plasmon polaritons (SPP) in a metal nanoparticle (MNP) and the excitons in semiconductor quantum dots (SQDs) in an SQD-MNP coupled system We propose a quantum transformation method to ... Au MNP for revealing the coupling between two SQDs induced by SPP field, as shown in left inset of Figure The interaction between the two identical SQDs can be neglected safely in the absence of...

Ngày tải lên: 21/06/2014, 17:20

... i.e by having a larger detuning energy Since the electronic properties of the quantum dots (QDs) depend on its size, shape, and surrounding matrix [35], this can be done by reducing the indium composition ... anti-reflection (AR) coating [32, 33] Since reflection loss accounts for *3 dB of the insertion loss [34], introducing AR coatings on both the front and back facets of our device will reduce the insertion loss ... utilizing the QD system Conclusion In summary, we report the preliminary results of a QD-EAM consisting of 10-layer InAs QDs as active region The QDEAM is a p-i-n ridge waveguide structure with intrinsic...

Ngày tải lên: 22/06/2014, 01:20

... technique is used in the present work for probing the electronic transitions in CdS quantum dots and correlating the observed data with the theoretical transitions obtained from a noninteracting particle ... limiting behavior The nonlinearity is probed using the z-scan technique Optical limiting can be due to a variety of nonlinear optical processes such as self focusing, self defocusing, nonlinear ... analysis, used in the present work and proposed for the first time by Nandakumar et al [13], is that it eliminates the use of bulk parameters in the calculation Including Coloumb interaction into the...

Ngày tải lên: 22/06/2014, 18:20

... strain (as high as 3.5 GPa) was induced in graphene by depositing a nm SiO2 followed by annealing, whereas a tensile strain (~ GPa) was obtained by depositing a thin silicon capping layer In the ... 2.4 Quantum model of Raman scattering In quantum theory, Raman scattering is considered as an inelastic collision process in which a quantum of the incident radiation is annihilated or a quantum ... scattering, which will be introduced later Besides the Rayleigh scattering, the remaining scattering has frequencies different from that of the incident radiation, as it originates from an inelastic...

Ngày tải lên: 13/09/2015, 21:36

... relaxation in InGaAs/InP was due the native interface asymmetry present in the structure or if spin relaxation is generally fast in InGaAs wells (see chapter 5) Finally, quantum beating of exciton spin ... have been distinguished by measuring electron spin relaxation in InGaAs/GaAs quantum wells The long spin lifetime implicates the NIA as the cause of the fast relaxation in InGaAs/InP Finally, the ... spin in semiconductors Currently, most mass produced semiconductor devices are Silicon based From an economic viewpoint, since the industrial production infrastructure is already in place, spin...

Ngày tải lên: 06/04/2013, 10:57

... enough to minimize the strain The obtained structures were doped in two different ways: with intra-dot doping (devices B44 and B52) and with inter-dot doping (devices B45 and B53) In devices ... 6:21 Sablon KA, Mitin V, Sergeev A, Little JW, Vagidov N, Reinhardt K, Olver KA: Nanoscale engineering: optimizing electron-hole kinetics of quantum dot solar cells In Proceedings of SPIE: April ... Thus, the built -in- dot charge in QD layers from the third to the eighth is directly determined by the inter-dot doping In Table 1, we present the builtin-dot charge, which is determined by the number...

Ngày tải lên: 20/06/2014, 22:20

... cultured in the cell culture medium containing μg/ mL adriamycin (Sigma) Both cell lines were maintained in RPMI-1640 medium containing 10% FCS, 100 U/ml of penicillin, and 100 μg/ml of streptomycin ... from the Institute of Hematology of Tianjin, Chinese Academy of Medical Sciences (Tianjin, China) To develop the drugresistant cell line (HepG2/ADM), adriamycin was added to HepG2 cells in a stepwise ... fixed in 100% methanol for 10 Cell monolayers were blocked in 5% BSA in PBS for 45 and incubated for h at room temperature with P-gp antibodies (Invitrogen, Beijing, China), followed by incubation...

Ngày tải lên: 21/06/2014, 03:20

... self-assembled quantum dots Phys Rev B 2000, 62:13595 Vdovin EE, Levin A, Patanè A, Eaves L, Main PC, Khanin YN, Dubrovskii YV, Henini M, Hill G: Imaging the electron wave function in self-assembled quantum ... spin injection in a ferromagnetic semiconductor heterostructure Nature 1999, 402:790 doi:10.1186/1556-276X-6-115 Cite this article as: dos Santos et al.: Spin effects in InAs self-assembled quantum ... emission are in anti-phase with each other The observed reduction of contact emission and increase of QD emission in low bias can be explained by the reduction of holes recombining in GaAs contact...

Ngày tải lên: 21/06/2014, 05:20

... optical gain enhancement [20] and photoluminescence enhancement [21], optical switching [22, 23], quantum information processing [24, 25] and electromagnetically induced transparency [26] QI in a ... the QDs doped in 3D–PCs have been widely studied, both experimentally and theoretically [15–19] Controlling spontaneous emission by using quantum optics would lead to several interesting effects, ... J.N Winn, R.D Meade, Photonic Crystals: Molding the Flow of Light (Princeton University Press, Princeton, 1995) C.M Soukoulis, Photonic Crystals and Light Localization in the 21st Century (Springer,...

Ngày tải lên: 22/06/2014, 00:20

... shown that, like single atom two- and three-level quantum systems, single QD can also exhibit interference phenomena including AutlerTownes splitting and gain without population inversion when driven ... experiments in the near future Competing interests The authors declare that they have no competing interests 11 Authors’ contributions JJL finished the main work of this article, including deducing the ... This peak splitting is very similar to the Rabi splitting of two-level systems in quantum optics [35] Furthermore, in conventional QD-linked biomedicine sensors, excited by single optical field,...

Ngày tải lên: 22/06/2014, 00:20

... fluorescence intensity was much stronger at a later time Figure shows that the fluorescence intensity increased almost linearly during the incubation period from 30 to 55 min, demonstrating a gradual increase ... obtained from the Cell Bank of Shanghai Science Academy were seeded onto a glass cover slip placed in a culture dish containing DMEM-H medium with 10% fetal bovine serum, 100 lg mL-1 streptomycin ... color at an early time (30 min), indicating there were no QDs in these lysosomes; while at a later time (55 min), most lysosomes showed a yellow color (a color representing the mixed fluorescence...

Ngày tải lên: 22/06/2014, 00:20

... to describe inter-atomic forces by using bond stretching and bending The role of strain (for three different shapes) in determining the bound levels is analyzed in detail Considering three different ... was grown on semi-insulating GaAs (001) substrates by using the solid-source molecular beam epitaxy (MBE) Five layers of nominally 3.0 momolayer (ML) InAs (quantum dots) were inserted between ... the quantum dot density in the lower layer is higher than that in the upper layer The near-infrared photoluminescence (PL) as a function of energy at 77 K is shown in Fig A main peak corresponding...

Ngày tải lên: 22/06/2014, 01:20

... translate QDs for use in clinical applications such as in vivo imaging in human subjects Modeling studies have revealed that two spectral windows exist for QD imaging in living subjects, one at ... exhibited high affinity integrin avb3 specific binding in cell culture and ex vivo In vivo NIR fluorescence (NIRF) imaging was carried out on athymic nude mice bearing subcutaneous integrin avb3-positive ... in vivo targeted imaging using QDs, as extravasation is not required to observe tumor signal Arginine–glycine–aspartic acid (RGD; potent integrin avb3 antagonist) containing peptides were conjugated...

Ngày tải lên: 22/06/2014, 18:20

... are growing when the magnetic field intensity is increased This is conditioned by growth of the magnetic quantization contribution into the CC energy increase Inter level distance is increased ... applications, in particular in large twodimensional focal plane arrays in the mid- and far infrared (M&FIR) region, having important applications in the fields of pollution detection, thermal imaging object ... while n1 and n2 are some numbers depending on the magnetic field intensity The expression (16) is an effective ¨ potential being incorporated in the Schrodinger equation for the ‘‘slow’’ subsystem...

Ngày tải lên: 22/06/2014, 19:20

... illustrate less strain relaxation for high index surfaces [19] The inhibition of strain relaxation inside the islands, by increasing the island internal energy term, should determine a delay in the 3D ... resulting edges of the QD During the SK growth of InAs 123 QDs, the main driving force forming islands is the strain relaxation, which permits relief of part of the strain induced by the lattice mismatch ... demonstrates the *12 meV exciton binding energy in these dots Due to the fact that the excitons in the WL easily interacted with the phonon and quenched, the integrated PL intensity of the 123 612 Nanoscale...

Ngày tải lên: 22/06/2014, 19:20

... 1), allowing a higher Q factor to be achieved in this spectral region Gaining a better insight into these experimental findings, we have studied spectra of CdTe/PS microspheres using low intensity ... certainly highly efficient having an intensity comparable to the Stokes PL as seen from Fig We found that the integrated intensity of ASPL has an almost linear dependence on the excitation intensity ... be distinguished in the spectral region between them To gain more insight into the WGM structure in the microcavity we carried out a fast Fourier analysis, which makes it possible to investigate...

Ngày tải lên: 22/06/2014, 22:20