Дисертації з теми "Semiconductor II-VI"
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Graham, Timothy Carl Maxwell. "Spectroscopy of II-VI semiconductor quantum dots." Thesis, Heriot-Watt University, 2006. http://hdl.handle.net/10399/103.
Claybourn, M. "Transient spectroscopy of II-VI semiconductors." Thesis, Durham University, 1985. http://etheses.dur.ac.uk/9298/.
Rueda-Fonseca, Pamela. "Magnetic quantum dots in II-VI semiconductor nanowires." Thesis, Université Grenoble Alpes (ComUE), 2015. http://www.theses.fr/2015GRENY015/document.
In this PhD work a novel type of magnetic semiconductor object has been developed: Cd(Mn)Te quantum dots embedded in ZnTe/ZnMgTe core-shell nanowires. The goal was to investigate the growth, by molecular beam epitaxy, and the fundamental properties of these complex heterostructures. For that purpose, two main issues were addressed: i) gaining control of the structural, electronic and magnetic properties of these quantum objects by mastering their growth; and ii) obtaining quantitative local knowledge on the chemical composition of those non-homogeneous nanostructures. To tackle these topics, our research was divided into four stages. The first stage was devoted to perform a quantitative study of the formation process of the Au particles that catalyze the growth of nanowires. The second stage involved the analysis of the mechanisms and parameters governing the growth of ZnTe nanowires. In particular, two different types of nanowires were found: cone-shaped nanowires with the zinc-blende crystal structure and cylinder-shaped nanowires with the hexagonal wurtzite structure. A diffusion-driven growth model is employed to fit some of the quantitative results presented in this part. The third stage focused on the insertion of pure CdTe quantum dots containing Mn ions in the core-shell nanowires. An initial study of the relevant parameters influencing the magneto-optical properties of these objects, such as the quantum dot confinement, the Mn incorporation, and the strain anisotropy, was performed. The four and last stage of this work concerned the quantitative interpretation of Energy-Dispersive X-ray spectroscopy measurements performed on single core-multishell nanowires. A geometrical model was proposed to retrieve the shape, the size and the local composition of the quantum dot insertions and of the multiple layers of the heterostructures. This study was coupled to other complementary characterization measurements on the same nanowire, such as cathodo-luminescence, micro-photo-luminescence and magneto-optical spectroscopy
Zhao, Lijuan. "Chemical syntheses and characterizations of II-VI semiconductor nanocrystals /." View abstract or full-text, 2007. http://library.ust.hk/cgi/db/thesis.pl?PHYS%202007%20ZHAO.
Luo, Ming. "Transition-metal ions in II-VI semiconductors ZnSe and ZnTe /." Morgantown, W. Va. : [West Virginia University Libraries], 2006. https://eidr.wvu.edu/etd/documentdata.eTD?documentid=4630.
Title from document title page. Document formatted into pages; contains xiv, 141 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 135-141).
Sugunan, Abhilash. "Fabrication and Photoelectrochemical Applications of II-VI Semiconductor Nanomaterials." Doctoral thesis, KTH, Funktionella material, FNM, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-95410.
QC 20120525
Shahid, Robina. "Green Chemical Synthesis of II-VI Semiconductor Quantum Dots." Doctoral thesis, KTH, Funktionella material, FNM, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-104980.
QC 20121115
Pawlis, Alexander. "Development and investigation of II-VI semiconductor microcavity structures." [S.l. : s.n.], 2003. http://deposit.ddb.de/cgi-bin/dokserv?idn=971579598.
Lee, Hyeokjin. "Synthesis and characterization of colloidal II-VI semiconductor nanorods." [Gainesville, Fla.] : University of Florida, 2005. http://purl.fcla.edu/fcla/etd/UFE0012984.
Sugunan, Abhilash. "Photochemical and Photoelectric Applications of II-VI Semiconductor Nanomaterials." Licentiate thesis, KTH, Functional Materials, FNM, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-12808.
In this work we investigated fabrication of semiconductor nanomaterials and evaluated their potential for photo-chemical and photovoltaic applications. We investigated two different II-VI semiconductor nanomaterial systems; (i) ZnO oriented nanowire arrays non-epitaxially grown from a substrate; and (ii) colloidal CdTe nanotetrapods synthesized by solution-based thermal decomposition of organo-metallic precursors. In both the cases our main focus has been optimizing material synthesis for improving potential applications based on photon-electron interactions.
We have studied the synthesis of vertically aligned ZnO nanowire arrays (NWA), by a wet chemical process on various substrates. The synthesis is based on epitaxial growth of ZnO seed-layer on a substrate in a chemical bath consisting of an aqueous solution of zinc nitrate and hexamethylenetetramine (HMT). We have suggested an additional role played by HMT during the synthesis of ZnO nanowire arrays. We have also extended this synthesis method to fabricate hierarchical nanostructures of nanofibers of poly-L-lactide acting as a substrate for the radially oriented growth of ZnO nanowires. The combination of high surface area of the nanofibrous substrate with the flexibility of the PLLA-ZnO hierarchical nanostructure enabled the proof-of-principle demonstration of a ‘continuous-flow’ water treatment system that could effectively decompose single and combination of known organic pollutants in water, as well as render common waterborne bacteria nonviable.
We have studied another chemical synthesis that is commonly used for size controlled synthesis of colloidal quantum dots, which was modified to obtain anisotropic nanocrystals mainly for CdE (E=S, Se, Te) compositions. In this work we demonstrate by use of oleic acid (instead of alkylphosphonic acids) it is possible to synthesize CdTe and CdSe nanotetrapods at much lower temperatures (~180 ºC) than what is commonly reported in the literature, with significantly different formation mechanism in the low-temperature reaction.
Finally, we have performed preliminary photoconduction measurements with CdTe nanotetrapods using gold ‘nanogap’ electrodes fabricated in-house, and obtain up to 100 times enhancement in current levels in the I–V measurements under illumination with a white light source.
QC20100607
Tang, Xiaodong. "MBE growth and characterization of II-VI semiconductor materials." Thesis, Heriot-Watt University, 2003. http://hdl.handle.net/10399/416.
Yuan, Chunze. "The Study of II-VI Semiconductor Nanocrystals Sensitized Solar Cells." Licentiate thesis, KTH, Teoretisk kemi och biologi, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-93752.
QC 20120425
Tran, Tuyen K. "Optical properties of II-VI semiconductor materials and superlattice structures." Diss., Georgia Institute of Technology, 1996. http://hdl.handle.net/1853/30929.
Ten, Sergey Yurevich 1966. "Carrier tunneling in III-V and II-VI semiconductor heterostructures." Diss., The University of Arizona, 1996. http://hdl.handle.net/10150/282245.
Davidson, Ian A. "The growth, processing and characterisation of II-VI semiconductor structures." Thesis, Heriot-Watt University, 2012. http://hdl.handle.net/10399/2662.
Beavis, A. W. "Electronic and optical properties of perfect and imperfect II-VI superlattices." Thesis, University of Newcastle Upon Tyne, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.293542.
Horsburgh, Gordon. "MBE growth and characterisation of II-VI semiconductor materials and devices." Thesis, Heriot-Watt University, 1997. http://hdl.handle.net/10399/1256.
Chen, Jie. "Spectroscopic Ellipsometry Studies of II-VI Semiconductor Materials and Solar Cells." University of Toledo / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1286813480.
Bajracharya, Pradeep. "Relaxation Dynamics and Decoherence of Excitons in II-VI Semiconductor Nanostructures." University of Cincinnati / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1186757546.
Blomfield, Christopher James. "Study of surface modifications for improved selected metal (II-VI) semiconductor based devices." Thesis, Sheffield Hallam University, 1995. http://shura.shu.ac.uk/19362/.
Urbaszek, Bernhard. "Fundamental studies of excitonic properties in II-VI semiconductors." Thesis, Heriot-Watt University, 2001. http://hdl.handle.net/10399/540.
Brown, Graeme. "Time-resolved ultrafast spectroscopy of wide-gap II-VI semiconductor quantum wells." Thesis, Heriot-Watt University, 2001. http://hdl.handle.net/10399/502.
Papageorgiou, Georgios. "Ultrafast nonlinear optical phenomena in wide-bandgap II-VI semiconductor quantum wells." Thesis, Heriot-Watt University, 2004. http://hdl.handle.net/10399/2026.
Kim, Jungtaek. "Electron-nuclear spin control and carrier spin dynamics in II-VI semiconductor." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät, 2016. http://dx.doi.org/10.18452/17524.
This work is composed of two parts of studies. The first part represents an electron-nuclear spin control in II-VI semiconductor quantum dots (QDs) by electrical currents via micro coils. Micrometer single turn coils are fabricated on top of heterostructures with charged CdSe/ZnSe QDs. Current injection creates magnetic fields in the range of some 10 mT which is strong enough to modulate the hyperfine interaction in CdSe. The micrometer-range diameter of coil allows for generation of fast field transient in the range of few ns. Using these advantages of micro coils, local control of the resident electron spin as well as read out of the nuclear spin state are demonstrated by electrical pulses. The second part presents charged carrier spin dynamics in ZnO quantum wells and epilayers using the optical transition of the negatively charged exciton X− and the neutral donor bound exciton D0X, respectively. The hole spin can be directly traced by the circular polarized photoluminescence of both complexes. The spin relaxation of the resident electrons and donor electrons is accessed via the bleaching of the spin selective excitation process. Longitudinal hole spin relaxation times of 80 and 140 ps are found for D0X and X−, respectively. Much longer longitudinal electron spin relaxation times in the several 100 ns range are uncovered if the hyperfine interaction is suppressed by a proper external magnetic field. A field strength of 2 mT is large enough proving that the extremely small value of the Overhauser field in ZnO caused by the very restricted number of magnetic nuclei interacting with the electron inside the donor volume.
Hall, Ralph Stephen. "Photocapacitance studies of transition metal related deep levels in III-V and II-VI semiconducters." Thesis, University of St Andrews, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.329476.
Jiang, Feng. "Ligand Controlled Growth of Aqueous II-VI Semiconductor Nanoparticles and Their Self-Assembly." Diss., The University of Arizona, 2013. http://hdl.handle.net/10150/311311.
Dagnelund, Daniel. "Magneto-optical studies of dilute nitrides and II-VI diluted magnetic semiconductor quantum structures." Doctoral thesis, Linköpings universitet, Funktionella elektroniska material, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-54695.
Khallaf, Hani. "Chemical Bath Deposition of Group II-VI Semiconductor Thin Films for Solar Cells Applications." Doctoral diss., University of Central Florida, 2009. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/2101.
Ph.D.
Department of Physics
Sciences
Physics PhD
Bradford, Christine Bradford. "MBE growth and characterisation of Zincblende MgS-based II-VI semiconductor material and devices." Thesis, Heriot-Watt University, 2002. http://hdl.handle.net/10399/407.
Laura, M. Robinson. "USING TIME-RESOLVED PHOTOLUMINESCENCE SPECTROSCOPY TO EXAMINE EXCITON DYNAMICS IN II-VI SEMICONDUCTOR NANOSTRUCTURES." University of Cincinnati / OhioLINK, 2001. http://rave.ohiolink.edu/etdc/view?acc_num=ucin980259259.
Gérard, Lionel. "Structures de semiconducteurs II-VI à alignements de bande de type II pour le photovoltaïque." Thesis, Grenoble, 2013. http://www.theses.fr/2013GRENY070.
This work focuses on the study of II-VI semiconductor heterostructures with type II band alignments, especially in the form of superlattices. This is a system that can be promising for photovoltaic applications, and my work is presented in this perspective. Thus the first part deals with a conceptual reflection on the contribution of type II interfaces for photovoltaics.In a second step I present a study on the growth of CdSe and ZnTe by molecular beam epitaxy on various substrates. These materials are particularly interesting and suitable for this application because they have a direct bandgap, are almost lattice-matched, present a type II band alignment, and CdSe shows a bandgap compatible with the solar spectrum. But in return these are binary semiconductors which have no atoms in common, so that the growth of samples with specific thicknesses close to the monolayer is challenging. For this reason we conducted a detailed study at the interfaces through analysis of X-ray diffraction and transmission electron microscopy, which allows us to conclude on the chemical nature of the atoms near the interfaces.This is followed by a detailed spectroscopy study on the effects of type II interfaces on the charge carriers through their energy and kinetics of recombination. We have developed an analytical model that allows to precisely adjust all the features observed in relation to these interfaces, and shows a very efficient charge separation mechanism. We show later that these effects are inherent characteristics of all interfaces of type II, regardless of materials and structures, and that they allow us to accurately extract the values of band offsets between different materials with type II band alignments
Hundt, Andreas. "Manipulation von Spinzuständen in einzelnen II-VI Halbleiter-Quantenpunkten." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2008. http://dx.doi.org/10.18452/15778.
Semiconductor quantum dots are objects on the nanometer scale, where charge carriers are confined in all three dimensions. This leads to a reduced interaction with the semiconductor lattice and to a discrete density of states. In the examined QD in II-VI seminconductor systems the large polar character of the bindings enables to observe particle interactions by spectroscopy of the photo-luminescence, making QD attractive for basic research. An odd number of carriers allows to study the latter in an unpaired state. By using polarization-resolved micro-PL spectroscopy, the spin-states of single, isolated QD can be studied reproducibly. Of special interest are exchange interactions in this few-particle system named trion. By excitation spectroscopy energetically higher states can be identified and characterized. The exchange interactions appearing here lead to state mixing and fine structure patterns in the spectra. Couplings in excited hole states show the way to the optical orientation of the resident electron spin. The spin configuration of the trion triplet state can be used to optically control the resident electron spin. Semimagnetic QD are focused in the second part of this work. The interaction with a paramagnetic environment of manganese spins leads to new magneto-optical properties of the QD. They reveal on a single dot level by line broadening due to spin fluctuations and by the giant Zeeman effect of the dot ensemble. Of special interest in this context is the influence of the reduced system dimension and the relatively larger surface of the system on the exchange mechanisms. The strong temperature dependence of the spin environment is used to systematically study the spin-lattice relaxation. Here, the PL of the QD ensemble monitors the spin temperature. The time constants in the mu range define the range for the incoherent switching of the Mn magnetization.
Babocsi, Krisztina. "Characterization of II-VI semiconductor nanostructures by low wavenumber raman- and four-wave-mixing spectroscopy." Doctoral thesis, [S.l. : s.n.], 2005. http://deposit.ddb.de/cgi-bin/dokserv?idn=975014862.
Little, Reginald Bernard. "The synthesis and characterization of some II-VI semiconductor quantum dots, quantum shells and quantum wells." Diss., Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/30573.
Yan, Shuke. "II-VI Semiconductor Nanowire Array Sensors Based on Piezotronic, Piezo-Phototronic and Piezo-Photo-Magnetotronic Effects." ScholarWorks@UNO, 2018. https://scholarworks.uno.edu/td/2502.
Bakarezos, Efthimios. "Ultrafast nonlinear optics of wide-gap II-VI quantum wells and polymeric materials." Thesis, Heriot-Watt University, 2000. http://hdl.handle.net/10399/519.
Kirmse, Holm. "Transmissionselektronenmikroskopische Untersuchungen von II-VI-Verbindungshalbleitern unterschiedlicher Dimensionierung." Doctoral thesis, [S.l. : s.n.], 2000. http://deposit.ddb.de/cgi-bin/dokserv?idn=962717835.
Swenberg, Johanes F. N. McGill T. C. McGill T. C. "Development of wide-bandgap II-VI semiconductor light-emitting device technology based on the graded injector design /." Diss., Pasadena, Calif. : California Institute of Technology, 1995. http://resolver.caltech.edu/CaltechETD:etd-10122007-142152.
Dooley, Chad Johnathan. "New Nanomaterials for Photovoltaic Applications: A Study on the Chemistry and Photophysics of II-VI Semiconductor Nanostructures." Thesis, Boston College, 2009. http://hdl.handle.net/2345/705.
This dissertation examines the chemistry and photophysics of semiconductor quantum dots with the intent of studying their capabilities and limitations as they pertain to photovoltaic technologies. Specifically, experiments are presented detailing the first time-resolved measurements of electron transfer in electronically coupled quantum rods. Electron transfer from the conduction band of CdTe was measured to occur on the 400 fs timescale (kET = 2.5 x 1012 s-1), more than 500x faster than previously believed. Additionally, the direct optical promotion of an electron from the valence band of CdTe was observed, occurring on the timescale of the pump pulse (~50 fs). Based on the determined injection rates, a carrier separation efficiency of > 90% has been calculated suggesting these materials are sufficient for use in solar energy capture applications where efficient carrier separation is critical. To this end, model photovoltaic cells were fabricated, and their power conversion efficiency and photon-to-current generation efficiency characterized. In devices based of CdSe and heteromaterial quantum rods we observed fill-factors on the order of 10-20% though with power conversion efficiencies of < 0.02%. It was discovered that using a high temperature annealing step, while critical to get electrochemically stable photoelectrodes, was detrimental to quantum confinement effects and likely removed any hQR specific capabilities. Additionally, a detailed study on the role of nucleotide triphosphate chemistry in stabilizing emissive CdS nanoparticles is presented. Specifically it was observed that in a neutral pH environment, GTP selectively stabilizes CdS quantum dots with diameters of ~4 nm while the other naturally occurring ribonucleotides do not yield emissive product. The selectivity is dependent on the presence of the nucleophilic N-7 electrons near a triphosphate pocket for Cd2+ complexation as well as an exocyclic amine to stabilize the resulting product particles. However, in an elevated pH environment, the nucleobase specificity is relaxed and all NTPs yield photo-emissive quantum dots with PLQEs as high as 10%
Thesis (PhD) — Boston College, 2009
Submitted to: Boston College. Graduate School of Arts and Sciences
Discipline: Chemistry
Kabir, Amin. "Phase coherent photorefractive effect in II-VI semiconductor quantum wells and its application for optical coherence imaging." University of Cincinnati / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1282315981.
Matos, Charlene Regina Santos. "Síntese e caracterização de nanopartículas de semicondutores metálicos do tipo II-VI." Universidade Federal de Sergipe, 2012. https://ri.ufs.br/handle/riufs/3486.
Inorganic nanomaterials are a class of advanced materials, which have been widespread in both science and nanotechnology. The use of nanomaterials in several areas makes nanoscience an interdisciplinary field. Some challenges, such as the type of synthesis and toxicity control should be explored, mainly because those materials can be controlled at the nanometer level by means of the synthesis variables. In this work, we performed the synthesis of cadmium telluride (CdTe) nanoparticles with the surface capped by a mixture of organic thiol stabilizers such as mercaptopropionic acid (MPA), cysteine (CYS), glutathione (GLU), and biopolymer sodium alginate (ALG). Synthesis were performed by two distinct aqueous methods hydrothermal and reflux and the synthesis parameters such as pH and ratio Cd/Te/stabilizer were fixed based on the literature. The colloidal dispersions obtain present remain stable for at least 3 months (time observed so far). Optical absorption spectra of all mixtures of CdTe - stabilizers presented a red shift with increasing synthesis time, and furthermore, the position of this band was at a wavelength below the bulk CdTe (790 nm). The emission spectra in all cases were intense, with little difference between them. The diameter of the particles, calculated from an empirical equation from the of maximum absorption wavelength, were comparable compared to those obtained by X-ray diffraction (XRD) (Scherrer equation) as well as transmission electron microscopy (TEM). The results from the three techniques agreed very well for CdTe via reflux. However for hydrothermal synthesis it was not possible to determine the diameter of the particles by TEM due to morphology of nanostructured aggregates. The crystal structures as obtained by XRD indicating the incorporation of sulfur atoms in the CdTe structure, in agreement to the literature for this type of synthesis. Infrared spectroscopy confirmed the presence of organic stabilizers on the surface of CdTe. The morfology of samples identified by TEM/HRTEM was different depending on the method of syntesis aggregates for the hydrothermal samples and isolated particles for reflux samples so the mechanisms of nucleation and growth were proposed oriented attachment (OA) and Ostwald ripening (OR) for synthesis CdTe-hydrothermal and reflux, respectively.
Os nanomateriais inorgânicos são uma classe de materiais avançados, que vêm sendo difundidos tanto em ciência como em nanotecnologia. O uso destes materiais está localizado em diversas áreas de atuação, fazendo com que tal classe seja interdisciplinar. Alguns desafios como o tipo de síntese e a toxidade devem ser explorados, principalmente porque estes materiais podem ser controlados a nível nanométrico por meio das variáveis de síntese. Neste trabalho, foi realizada a síntese de nanopartículas de Telureto de Cádmio (CdTe) com a superfície coberta pela mistura de estabilizantes orgânicos tióis tais como, ácido mercaptopropiônico (MPA), cisteína (CYS) e glutationa (GLU) e o biopolímero alginato de sódio (ALG). Esta síntese foi realizada por dois métodos aquosos, via hidrotermal e refluxo, e os parâmetros de síntese como pH e relação Cd/Te/estabilizante foram fixos com base na literatura. As dispersões coloidais obtidas apresentaram-se com estabilidade coloidal por pelo menos 3 meses (tempo observado até o momento). Os espectros eletrônicos de absorção óptica de todas as misturas de CdTe-estabilizantes se apresentaram largos, com deslocamento para o vermelho com o aumento do tempo de síntese, e além disso, a posição desta banda estava em comprimento de onda abaixo do CdTe bulk (790 nm), indicando confinamento quântico. Os espectros de emissão em todos os casos foram intensos e com pouca diferença entre os mesmos. Os diâmetros das partículas foram calculados usando-se uma fórmula empírica, a partir do comprimento de onda máximo de absorção e comparado aos resultados obtidos por difratometria de raios X (XRD) (equação de Scherrer) e por microscopia eletrônica de transmissão (TEM). Os resultados das três técnicas corroboram entre si para as amostras de CdTe via refluxo. Contudo, no caso do hidrotermal, não foi possível determinar os diâmetros por TEM porque a morfologia foi de agregados nanoestruturados. As estruturas cristalinas forma obtidas por XRD, indicando a incorporação de átomos de enxofre na estrutura do CdTe, estando de acordo com a literatura para o tipo de síntese. A espectroscopia de infravermelho confirmou a presença dos estabilizantes orgânicos na superfície do CdTe. A morfologia identificada por TEM/HRTEM das amostras sintetizadas pelas duas sínteses foi diferente agregados para a síntese hidrotermal e partículas isoladas para refluxo sendo que os mecanismos proposto para nucleação e crescimento foram o oriented attachment (OA) e o Ostwald ripening (OR) para CdTe-hidrotermal e o CdTe-refluxo, respectivamente.
Liu, Feng [Verfasser], Dmitrij G. [Akademischer Betreuer] Jakovlev, and Heinz [Akademischer Betreuer] Hövel. "Magneto-optical properties of II-VI semiconductor colloidal nanostructures / Feng Liu. Betreuer: Dmitrij G. Jakovlev. Gutachter: Heinz Hövel." Dortmund : Universitätsbibliothek Dortmund, 2013. http://d-nb.info/1099958261/34.
Flissikowski, Timur. "Coherence properties of single self-assembled quantum dots." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2005. http://dx.doi.org/10.18452/15178.
Semiconductor quantum dots (QD) have attracted considerable interest during the past years as possible candidates for quantum information processing. Due to the confinement potential in such structures, the density of states in a single QD is discrete. If the states are well separated in energy the coupling to the environment is expected to be smaller, implying that coherence is maintained during the exciton lifetime. In the present work CdSe in ZnSe QDs are used. Two kinds of coherence phenomena, reflecting the time evolution of such a quantum system, are studied by use of optical methods. In case of optical coherence, an excited state which is radiatively coupled to a ground state interacts with an external electro-magnetic field. The experimental technique of temporal coherent control is applied via a two photon process on the biexciton state and also by a single photon process on the excited state in a single QD. As a result optical coherence times below 10 ps are found for the excited state, while for the biexciton only a lower limit on a 10 ps timescale was elaborated. The second phenomena is quantum coherence and describes the phase memory between two states in the same QD. It is studied in this work by the analysis of the observed quantum beats in the time resolved photoluminescence emission (PL) of the ground state exciton in a single QD. As a result it was found that there is no measurable decoherence between the two substates of the ground state exciton during the exciton lifetime of about 300 ps. In a third group of experiments the longitudinal spin relaxation time is investigated on a single carrier level. The used QD sample contains charged QDs with resident electrons, which provide direct access to the separate spin dynamic of the holes. Different experiments carried out, yielding a longitudinal spin relaxation time for a single hole on a 10 ns timescale.
Frey, Alexander [Verfasser], and Karl [Akademischer Betreuer] Brunner. "Spin-Dependent Tunneling and Heterovalent Heterointerface Effects in Diluted Magnetic II-VI Semiconductor Heterostructures / Alexander Frey. Betreuer: Karl Brunner." Würzburg : Universitätsbibliothek der Universität Würzburg, 2013. http://d-nb.info/1037311388/34.
Talapin, Dmitri V. "Experimental and theoretical studies on the formation of highly luminescent II-VI, III-V and core shell semiconductor nanocrystals." [S.l. : s.n.], 2002. http://deposit.ddb.de/cgi-bin/dokserv?idn=964732297.
Eley, Clive William. "The rational design of photocatalytic semiconductor nanocrystals." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:ee29c922-857c-432a-8316-a7e04c822b1d.
Pedetti, Silvia. "Synthesis and optical properties of II-VI colloidal two-dimensional nanocrystals : homo- and hetero-structures." Thesis, Paris 6, 2015. http://www.theses.fr/2015PA066755.
This thesis project is based on the development of a novel class of colloidal two-dimensional nanocrystals, i.e. nanoplatelets (NPLs), composed of cadmium chalcogenides. These nanocrystals, in analogy to quantum wells, are characterized by an exciton confinement along one direction, i.e. the thickness, which can be controlled at atomic level. Nanoplatelets possess unique optical features as an excellent spectral resolution and good quantum yields. As consequence these nanocrystals are potential candidates for the fabrication of optoelectronic devices such as electroluminescent diodes or photo-detectors. However, for this aim it is necessary to enlarge the range of the absorption and emission wavelengths and to increase their quantum yield. For this reason, we investigated the colloidal synthesis of II-VI homo- and hetero-nanoplatelets which have been characterized by UV-Vis and photoluminescence spectroscopy, by X-ray diffraction and by electronic microscopy. First, we optimized the synthesis of CdTe NPLs using colloidal synthesis based on precursors injection at high temperatures. Then, we focused on more complexes hetero-structures. For example, through lateral extension reactions we obtained CdSe/CdTe core/crown NPLs which possess a type-II electronic structure. Successively, we studied the synthesis of core/shell NPLs by the growth of a second semiconductor layer along the thickness of NPLs cores. Depending on the core and shell chemical composition we could engineer the band gap of the nanoplatelets between type-I, quasi type-II and type-II electronic structures
Kim, Jungtaek Verfasser], Oliver [Gutachter] [Benson, W. Ted [Gutachter] Masselink, and Dimitri [Gutachter] Yakovlev. "Electron-nuclear spin control and carrier spin dynamics in II-VI semiconductor / Jungtaek Kim. Gutachter: Oliver Benson ; W. Ted Masselink ; Dimitri Yakovlev." Berlin : Mathematisch-Naturwissenschaftliche Fakultät, 2016. http://d-nb.info/1103570781/34.
Pfeuffer, Rebekka Christina [Verfasser], and Charles [Gutachter] Gould. "Growth and characterization of II-VI semiconductor nanowires grown by Au catalyst assisted molecular beam epitaxy / Rebekka Christina Pfeuffer ; Gutachter: Charles Gould." Würzburg : Universität Würzburg, 2016. http://d-nb.info/1121508308/34.
Kim, Jungtaek [Verfasser], Oliver [Gutachter] Benson, W. Ted [Gutachter] Masselink, and Dimitri [Gutachter] Yakovlev. "Electron-nuclear spin control and carrier spin dynamics in II-VI semiconductor / Jungtaek Kim. Gutachter: Oliver Benson ; W. Ted Masselink ; Dimitri Yakovlev." Berlin : Mathematisch-Naturwissenschaftliche Fakultät, 2016. http://d-nb.info/1103570781/34.