Дисертації з теми "Hexagonal Boron Nitride Films"
Оформте джерело за APA, MLA, Chicago, Harvard та іншими стилями
Ознайомтеся з топ-50 дисертацій для дослідження на тему "Hexagonal Boron Nitride Films".
Біля кожної праці в переліку літератури доступна кнопка «Додати до бібліографії». Скористайтеся нею – і ми автоматично оформимо бібліографічне посилання на обрану працю в потрібному вам стилі цитування: APA, MLA, «Гарвард», «Чикаго», «Ванкувер» тощо.
Також ви можете завантажити повний текст наукової публікації у форматі «.pdf» та прочитати онлайн анотацію до роботи, якщо відповідні параметри наявні в метаданих.
Переглядайте дисертації для різних дисциплін та оформлюйте правильно вашу бібліографію.
Alharbi, Abdulaziz. "Deformation of hexagonal boron nitride." Thesis, University of Manchester, 2018. https://www.research.manchester.ac.uk/portal/en/theses/deformation-of-hexagonal-boron-nitride(6c6013c4-8c17-4dec-b250-ed3f0baea7ed).html.
Повний текст джерелаCamurlu, Hasan Erdem. "Carbothermic Production Of Hexagonal Boron Nitride." Phd thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/3/12607808/index.pdf.
Повний текст джерелаB2O3 mixtures was slower than activated C&ndash
B2O3 mixtures. It was concluded that B4C is not a necessary intermediate product in the carbothermic production of h-BN. Some additives are known to catalytically affect the h-BN formation. The second aim of this study was to examine the catalytic effect of some alkaline earth metal oxides and carbonates, some transition metal oxides and cupric nitrate. It was found that addition of 10wt% CaCO3 into the B2O3+C mixture was optimum for increasing the rate and yield of h-BN formation and decreasing the B4C amount in the products and that the reaction was complete in 2 hours. CaCO3 was observed to be effective in increasing the rate and grain size of the formed h-BN. Addition of cupric nitrate together with CaCO3 provided a further increase in the size of the h-BN grains.
Khan, Aamar Farooq. "The electrochemistry of 2D hexagonal boron nitride." Thesis, Manchester Metropolitan University, 2018. http://e-space.mmu.ac.uk/620319/.
Повний текст джерелаAyoob, Raed. "Dielectric properties of hexagonal boron nitride polymer nanocomposites." Thesis, University of Southampton, 2017. https://eprints.soton.ac.uk/417272/.
Повний текст джерелаPelini, Thomas. "Optical properties of point defects in hexagonal boron nitride." Thesis, Montpellier, 2019. http://www.theses.fr/2019MONTS139.
Повний текст джерелаThe purpose of this thesis was to explore and caracterize optically the point defects in hexagonal boron nitride. The study of defects in this semiconductor is of fundamental importance firstly for the material science in which it plays a key role thanks to its lamellar structure (2D material) and its high thermal and chemical stability, and secondly for the quantum nanotechnology domain where its large bandgap (~ 6 eV) allows for exploiting deep levels point imperfections as «artificial atom» in the crystal lattice. During this thesis, defects in two spectral ranges have been studied: a first family emitting in the visible wavelengths, and a second one emitting in the ultraviolet range.Firstly, we made use of a scanning confocal microscope working in ambient conditions and at visible wavelengths. The recording of photoluminescence spatial maps permited to show the existence of localised hot spot of light, under the diffraction limit of the miscroscope, and emitting around 600 nm (2 eV). Time photon-correlation measurements revealed on one hand that we were dealing with single quantum emitters, and on the other hand allowed for probing the photodynamics of those systems, in particular at very long time-scale. Various photostability regimes are observed and discussed. Last but not least, power resolved study was also performed and demonstrated that a number of the emitters (~ 5%) are photo-stable at high excitation power and saturate at few millions counts per second: those point defects are one of the brightest single-photon source at room temperature in solid-state systems.Secondly, we explored the defects in the ultraviolet spectral range. A prerequisite to the engineering of defects in semiconductors for technological applications is the knowledge of their chemical origin. With this in mind, we studied shallow and deep levels in carbon-doped hBN samples by combining macro-photoluminescence and reflectance measurements. We showed the existence of new optically-active transitions (around 300 nm) and discussed the implication of carbon in these levels. The in-depth study of these levels have required the development of a new scanning micro-photoluminescence confocal microscope operating at 266 nm under cryogenic environment. The design and performances of the optical system are described, and the experimental challenges explained in details. Using this new setup, we went further into the examination of the deep levels. In particular, a study was carried out regarding the spatial correlation between these new spectral lines and the well-known point defect at 4.1 eV. Then, we used new crystals with isotopically-purified carbon doping as a strategy to investigate the long-standing question concerning the chemical origin of the 4.1 eV defect. Through this attempt, we brought to light the spatial dependence of the optical features for this specific emitter. Last but not least, we present our work dedicated to isolate the emission of a single 4.1 eV defect. We studied the photoluminescence of thin undoped flakes, pre-characterized with an electron microscope, that contain a low density of emitters, and inspected in particular their photostability in these thin crystals
Krishna, Kumar Roshan. "High temperature quantum transport in graphene/hexagonal-boron nitride heterostructures." Thesis, Lancaster University, 2017. http://eprints.lancs.ac.uk/88867/.
Повний текст джерелаElias, Christine. "Optical spectroscopy of hexagonal boron nitride : from bulk to monolayer." Thesis, Montpellier, 2020. http://www.theses.fr/2020MONTS054.
Повний текст джерелаHexagonal boron nitride (h-BN) or “white graphite” is a semiconductor which has a wide bandgap (~ 6 eV) and whose crystalline structure is close to that of graphite: it is formed by planes of atoms arranged in a hexagonal form. The interaction between the planes is of Van-der-Waals type. In 2004, h-BN demonstrated its ability to efficiently emit light in the deep UV (~ 200 nm) in crystals synthesized in NIMS laboratory in JAPAN. These results have attracted the attention of the community of semiconductors to the possibility of being used as a source of light for deep UV applications.The nature of the band gap in bulk h-BN has been the subject of a debate for over 12 years and it has been studied by theoretical calculations and by experiments. In 2016, the gap was demonstrated to be indirect based on 2-photon spectroscopy measurements. Indirect exciton and phonon-assisted recombination were observed by photoluminescence in h-BN.In h-BN, like in other 2D materials, when changing from a 3D system (massive) to a 2D system (monolayer), the nature of the gap changes. The calculations show a change from an indirect gap (bulk) to a direct gap (monolayer). This indirect-direct gap transition has never been observed in h-BN, and consequently the opto-electronic properties of the monolayer have never been studied. During this thesis, we studied for the first time the optical properties of the BN monolayer (mBN) by performing optical spectroscopy (macro-PL and reflectivity) in mBN samples grown by MBE at high temperature on graphite substrates (HOPG).Our results demonstrated for the first time the possibility to grow mBN (3.5 Å) by MBE technique. Our optical measurements demonstrated the presence of an optical transition at 6.1 eV associated to the direct gap in the mBN
Akyildiz, Ugur. "Effect Of Sodium Carbonate On Carbothermic Formation Of Hexagonal Boron Nitride." Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12612579/index.pdf.
Повний текст джерелаWoods, Colin. "Investigations into the interfacial interaction of graphene with hexagonal boron nitride." Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/investigations-into-the-interfacial-interaction-of-graphene-with-hexagonal-boron-nitride(de99f43b-790f-4a32-b696-060ed700a5bd).html.
Повний текст джерелаCrane, Thomas Philip. "An NMR study of helium-3 adsorbed on hexagonal boron nitride." Thesis, Royal Holloway, University of London, 1998. http://digirep.rhul.ac.uk/items/1d14fa0b-8f29-7b7a-f32b-7c23bae45c35/1/.
Повний текст джерелаYazbeck, Joseph. "Investigations of hexagonal boron nitride as a semiconductor for neutron detection." Thesis, Kansas State University, 2012. http://hdl.handle.net/2097/14163.
Повний текст джерелаDepartment of Mechanical and Nuclear Engineering
Jeffrey Geuther
William L. Dunn
The properties of hexagonal boron nitride (h-BN) as a semiconductor neutron detection medium were investigated. Single h-BN crystal domains were synthesized by the Chemical Engineering department at Kansas State University (KSU) using crystallization from molten metal solutions. At Texas Tech University (TTU), a detector was fabricated using epitaxial h-BN growth on a sapphire substrate where metallic micro-strip contacts 5 [mu]m apart and 5 nm thick where deposited onto the un-doped h-BN. In this research both the crystal domains synthesized at KSU and the detector fabricated at TTU were tested for neutron response. Neutron irradiation damage/effects were studied in pyrolytic h-BN by placing samples in the central thimble of the TRIGA MARK II reactor at KSU and irradiating at increasing neutron fluences. The domains synthesized at KSU as well as the detector fabricated at TTU showed no response to neutron activity on a MCA pulse height spectrum. Conductivity analysis showed abrupt increases in the conductivity of the pyrolytic h-BN at around a fluence of 10[superscript]1[superscript]4 neutrons per cm[superscript]2. Bandgap analysis by photoluminescence on the irradiated pyrolytic h-BN samples showed shifts in energy due to towards plane stacking disorders upon neutron irradiation. Future efforts may include the introduction of dopants in h-BN growth techniques for charge carrier transport improvement, and mitigation of plane stacking disorders.
Zhou, Vivian. "Optical Spectroscopic Studies of Hexagonal Boron Nitride for Quantum Information Applications." Case Western Reserve University School of Graduate Studies / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=case1555257441049214.
Повний текст джерелаNakhaie, Siamak. "Growth of graphene/hexagonal boron nitride heterostructures using molecular beam epitaxy." Doctoral thesis, Humboldt-Universität zu Berlin, 2018. http://dx.doi.org/10.18452/19190.
Повний текст джерелаTwo-dimensional (2D) materials offer a variety of novel properties and have shown great promise to be used in a wide range of applications. Recently, hexagonal boron nitride (h-BN) has attracted significant attention due to its suitability for integration into heterostructures with other 2D materials. In particular, van der Waals heterostructures combining h-BN and graphene offer many potential advantages, but remain difficult to produce as continuous films over large areas. This thesis presents an investigation regarding the growth of h-BN and vertical heterostructures of graphene and h-BN on Ni substrates using molecular beam epitaxy (MBE). The growth of h-BN from elemental sources of B and N was investigated initially by using Ni as the growth substrate. The presence of crystalline h-BN was confirmed using Raman spectroscopy. Growth parameters resulting in continuous and atomically thin h-BN films were obtained. By systematically varying the growth temperature and time the structural quality as well as the nucleation and growth behavior of h-BN was studied. Corresponding observations such as changes in preferred nucleation site, crystallite size, and coverage of h-BN were discussed. Growth of h-BN/graphene vertical heterostructures (h-BN on graphene) over large areas was demonstrated by employing a novel MBE-based technique, which allows both h-BN and graphene to form in the favorable growth environment provided by Ni. In this technique, graphene forms at the interface of h-BN/Ni via the precipitation of C atoms previously dissolved in the thin Ni film. No evidence for the formation of BCN alloy could be found. Additionally, the suitability of ultraviolet Raman spectroscopy for characterization of h-BN/graphene heterostructures was demonstrated. Finally, growth of large-area graphene/h-BN heterostructures (graphene on h-BN) was demonstrated via the direct deposition of C on top of MBE-grown h-BN.
Ozkenter, Ali Arda. "Effect Of Calcium Oxide Addition On Carbothermic Formation Of Hexagonal Boron Nitride." Master's thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/12610740/index.pdf.
Повний текст джерелаC and effect of CaO addition into the initial B2O3 &
#8211
active C mixture were investigated during this study. Reaction products were characterized by powder X-ray diffraction, scanning electron microscopy (SEM) and quantitative chemical analysis. Main aim of this study was to investigate the presence of a second reaction mechanism that catalytically affects h-BN formation during CaO or CaCO3 addition into the initial mixture. It was found that similar to CaCO3 addition, CaO addition has a catalytic effect on carbothermic formation h-BN. In order to investigate the reaction mechanism experiments with B2O3 &
#8211
CaO mixtures without active carbon addition into the mixture were conducted. Furthermore nucleation of h-BN from calcium borate melts had been investigated and experiments were conducted with h-BN addition into CaO &
#8211
B2O3 mixtures. It was concluded that nucleation of h-BN in calcium borate slags under experimental conditions is not possible. Hexagonal BN should be present in the system in order to activate the second nitrogen dissolution followed by h-BN precipitation mechanism. Highest efficiency was achieved in the experiment conducted with CaCO3 addition and largest particle size was observed during the experiment conducted to investigate the effect of nucleation.
He, Qinyue. "The Study of Comprehensive Reinforcement Mechanism of Hexagonal Boron Nitride on Concrete." Thesis, University of North Texas, 2015. https://digital.library.unt.edu/ark:/67531/metadc804976/.
Повний текст джерелаYuan, Weiqiang. "Simulation of Hexagonal Boron Nitride Deep Ultra-Violet ac-Driven Electroluminescence Devices." Ohio University / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1586958083835764.
Повний текст джерелаSperber, Jared L. "Investigations of hexagonal boron nitride: bulk crystals and atomically-thin two dimensional layers." Thesis, Kansas State University, 2016. http://hdl.handle.net/2097/32509.
Повний текст джерелаDepartment of Chemical Engineering
James H. Edgar
Hexagonal boron nitride has been used as an inert, refractory material with excellent resistance to thermal decomposition and oxidation for more than fifty years. In the past few years, hBN has been targeted for potential electrical and optical devices such as neutron detectors, ultraviolet light emitters, deep ultraviolet light detectors, and substrates for graphene and other atomically-thin two-dimensional materials. All of these potential applications benefit from high quality, single crystals, with thicknesses varying from nanometers to microns. This research was undertaken to investigate four aspects of hBN crystal growth and recovery. (1) In an effort to optimize hBN crystal growth from a nickel-chromium flux, a series of stepped cooling experiments were undertaken. The temperature profile was stepped in a way as to promote growth in both the a and c directions, at their optimal growth conditions. Crystals were found to be typically 100-500 µm across and thickness of approximately 20-30 µm with a pyramid-like crystal habit. (2) A method for the removal of hBN crystals prior to freezing of the metal flux was demonstrated using a specialized hot pressed boron nitride crucible capable of removing hBN crystals from the flux in situ. (3) Growth of isotopically pure hBN crystals was undertaken. By modifying the crucible material for solution growth, enrichment of hBN crystals over 90% was accomplished. (4) Exfoliation of hBN has many potential applications, specifically as graphene-hBN heterostructures where layers approaching thicknesses of single atoms are most effective surface to interact with graphene as an electronic device. Several methods were tested toward exfoliating a single crystal resulting in few-layered hexagonal boron nitride nanosheets. As a result of these investigations a greater understanding of hBN bulk growth, its isotopic enrichment, its recovery, and its exfoliation was obtained.
Anutgan, Mustafa. "Investigation Of Plasma Deposited Boron Nitride Thin Films." Master's thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/12608611/index.pdf.
Повний текст джерелаHui, Fei. "Chemical vapor deposition of hexagonal boron nitride and its use in electronic devices." Doctoral thesis, Universitat de Barcelona, 2018. http://hdl.handle.net/10803/663391.
Повний текст джерелаLos dieléctricos son materiales aislantes utilizados en muchos dispositivos electrónicos (por ejemplo condensadores, transistores, baristores), en los que juegan un papel muy importante. En realidad, el dieléctrico es probablemente la parte más crítica en la gran mayoría de dispositivos electrónicos, ya que casi siempre está expuesto a campos eléctricos que pueden degradar sus prestaciones. El dióxido de silicio (SiO2) ha sido el material aislante tradicionalmente utilizado en la industria; sin embargo la miniaturización de los dispositivos requirió una reducción del grosor de los dieléctricos SiO2, lo que provocó un incremento dramático de la corriente de fugas y el fallo del dispositivo entero. Actualmente los dispositivos electrónicos más avanzados utilizan materiales aislantes con una constante dieléctrica alta (por ejemplo HfO2, Al2O3 y TiO2), y así no es necesario reducir tanto su grosor, lo que mantiene una baja corriente de fugas. Sin embargo, estos materiales muestran muchos problemas intrínsecos, y también una mala interacción con materiales adyacentes. Por lo tanto, la carrera para encontrar un material dieléctrico ideal para dispositivos electrónicos sigue abierta. En este contexto, los materiales bidimensionales se han convertido en una seria opción, no sólo por sus excelentes propiedades, sino también gracias al desarrollo de nuevos métodos de síntesis escalables. En esta tesis doctoral he investigado el uso de nitruro de boro hexagonal (h-BN), monocapa y multicapa, como material dieléctrico en dispositivos electrónicos, ya su banda de energías prohibidas es de ~5.9 eV. Mi trabajo se ha focalizado en la síntesis de h-BN mediante el método chemical vapor deposition, el estudio de sus propiedades morfológicas y eléctricas a escala nanométrica, y sus prestaciones como dieléctrico en diferentes dispositivos (condensadores y memristores). Nuestros experimentos indican que h-BN es un material dieléctrico muy fiable, y que es apto para su uso en dispositivos. Sus prestaciones dependen de diferentes parámetros, como el sustrato en el que ha sido crecido, su grosor, y los materiales usados como electrodos adyacentes. Además, h-BN muestra propiedades adicionales nunca observadas en dieléctricos tradicionales, como modulación de la resistividad volátil, lo que podría extender su uso a nuevas aplicaciones.
Kahramansoy, Eylem. "Production Of Hexagonal Boron Nitride By Carbothermic Reduction Of Colemanite-boric Oxide Mixtures." Master's thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12613595/index.pdf.
Повний текст джерелаRegion in Turkey was investigated by subjecting pellets prepared from B2O3, activated carbon and colemanite mixtures to nitrogen gas at 1500°
C. Similar to CaCO3 addition, colemanite addition to the B2O3-C mixtures resulted in higher amounts of h-BN in the final products. As a result of the experiments conducted with colemanite and CaCO3 additions providing the same quantity of CaO to the initial mixtures, similar amounts of hexagonal BN in the reaction products were observed. As a result of the experiments conducted with different compositions of colemanite- B2O3- C mixtures, 5 wt % colemanite addition was determined to be the optimum composition giving the highest amount of hexagonal BN in the reaction products. Increasing duration of the experiments increased the amount and particle size of h-BN formed in the products. Optimum amount of colemanite addition resulted in higher amounts and coarser particles of h-BN in the products than the optimum amounts of CaCO3 addition.
Fang, Wenjing Ph D. Massachusetts Institute of Technology. "Synthesis of bilayer graphene and hexagonal boron nitride by chemical vapor deposition method." Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/103724.
Повний текст джерелаCataloged from PDF version of thesis.
Includes bibliographical references (pages 156-165).
The aim of this thesis is two-fold: the first is to develop a reliable method for synthesizing bilayer graphene using chemical vapor deposition (CVD) method and to understand the growth mechanism. The second part involves exploring methods of synthesizing hexagonal boron nitride (hBN). The successful isolation of monolayer graphene in 2004 has attracted many researchers to search for potential applications of graphene and other two-dimensional materials in electronic and optical devices. However, the Scotch-tape method sets contraints for such applications due to the limited size and randomized location of obtained flakes. Thus, synthesizing large-area, high-quality two dimensional materials is highly desirable. This thesis seeks to develop a method to produce both bilayers and hBN with large area by CVD method and to investigate the underlying growth mechanisms for better control over the thickness, uniformity and stacking orientation.
by Wenjing Fang.
Ph. D.
López, Josué Jacob. "Characterization of nanostructured hexagonal boron nitride patterned via high-resolution ion beam lithography." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/111919.
Повний текст джерелаCataloged from PDF version of thesis.
Includes bibliographical references (pages 51-57).
The forefront of polariton research in two-dimensional (2D) materials focuses on pushing the limits of patterning 2D materials into nanoresonators and other nanophotonic structures that manipulate highly confined polaritons for technologically relevant near-IR and mid-IR applications. Furthermore, tuning the properties of hexagonal boron nitride, graphene, and other 2D materials in-plane and stacking them into heterostructures has the potential to create hybrid optical, electronic, thermal, and mechanical properties with a wealth of new functions. To fully tailor these novel properties, controlled nanoscale patterning of these and other van der Waals materials is essential. Moreover, it becomes imperative to understand how patterning and geometries modify the properties within each layer or introduce defects that affect the interfaces of layered 2D heterostructures. Herein, we demonstrate high-resolution patterning of h-BN via both helium and neon ion beams and pattern a h-BN grating with a 35 nm pitch and 20 nm feature size. We study varying degrees of nanostructuring and defects via Raman spectroscopy, photo-thermal microscopy, and scattering-type scanning near-field optical microscopy and observe complimentary information about the phonon modes and the absorption and scattering of light from such nanostructures. Specifically, we observe geometry and layer dependent photo-thermal expansion of h-BN nanostructures that are mediated by phonons. This work demonstrates a thorough understanding of directly patterned 2D materials with ion beams and demonstrates that far-field and near-field measurements are essential in understanding how the nanostructuring of 2D materials can tune their properties.
by Josué Jacob López.
S.M.
Sanchez-Yamagishi, Javier Daniel. "Superlattices and quantum spin Hall states in graphene and hexagonal boron nitride heterostructures." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/99289.
Повний текст джерелаCataloged from PDF version of thesis.
Includes bibliographical references (pages 159-178).
Two-dimensional (2d) layered materials, such as graphene and hexagonal boron nitride (hBN), can be isolated separately and then stacked together to form heterostructures with crystalline interfaces between the layers. In this thesis, I present a series of experiments which explore the quantum transport of electrons in heterostructures made from graphene and hBN. Depending on the relative alignment, or "twist", between the layers, a crystal of hBN can be either a non-perturbing substrate for the graphene, or a method to induce a band gap and superlattice potential for the graphene electrons. In the case of two stacked graphene layers, a relative twist can electronically decouple the layers from each other, despite a tiny 0.34nm interlayer spacing. This twist-dependent physics can be used to realize new electronic states in graphene, especially in the presence of strong magnetic fields and electron-electron interactions. By applying a strong tilted magnetic field to graphene which is decoupled from its hBN substrate, we are able to realize a quantum spin Hall state and measure its electronic properties. An analogous bilayer quantum spin Hall state is also realized in twisted bilayer graphene, by taking advantage of the twist decoupling between the layers and the effects of electron-electron interactions. A different set of experiments explores the competition of a magnetic field with the effects of the superlattice potential which arises when a graphene sheet is nearly aligned to its hBN substrates. The large superlattice potential allows us to study graphene transport in Hofstadter's butterfly-the fractal spectrum for electrons under the simultaneous influence of a lattice and a magnetic field.
by Javier Daniel Sanchez-Yamagishi.
Ph. D.
Clubine, Benjamin. "Synthesis and characterization of bulk single crystal hexagonal boron nitride from metal solvents." Thesis, Kansas State University, 2012. http://hdl.handle.net/2097/13639.
Повний текст джерелаDepartment of Chemical Engineering
James H. Edgar
Boron nitride is a purely synthetic material that has been known for over 150 years but only recently has sparked interest as a semiconductor material due to its potential in ultraviolet lasing and neutron detection. Thin-layer hexagonal boron nitride (hBN) is probably most attractive as a complementary material to graphene during its intense research endeavors. But for hBN to be successful in the realm of semiconductor technology, methods for growing large single crystals are critical, and its properties need to be accurately determined. In this study, hBN crystals were grown from metal solvents. The effects of soak temperature, soak time, source materials and their proportions on hBN crystal size and properties were investigated. The largest crystals of hBN measured five millimeters across and about 30 micrometers thick by precipitation from BN powder dissolved in a nickel-chromium solvent at 1700°C. High temperatures promoted outward growth of the crystal along the a-axis, whereas low temperatures promoted growth along the c-axis. Crystal growth at high temperatures also caused bulk hBN to adopt a triangular habit rather than a hexagonal one. A previously unreported method of synthesizing hBN was proven successful by substituting BN powder with elemental boron and a nitrogen ambient. XRD and Raman spectroscopy confirmed hBN from solution growth to be highly crystalline, with an 8.0 cm[superscript]-1 FWHM of the Raman peak being the narrowest reported. Photoluminescence spectra exhibited peaks mid-gap and near the band edge, suggesting impurities and defects in the hBN samples. However, high-purity reactants and post-growth annealing showed promise for synthesizing semiconductor-grade hBN. Several etchants were explored for defect-selective etching of hBN. A molten eutectic mixture of KOH/NaOH was the most effective defect-selective etchant of hBN at temperatures of 430-450°C for about one minute. The two prevalent hexagonal etch pit morphologies observed were deep, pointed-bottom pits and shallow, flat-bottom pits. TEM and SAED confirmed basal plane twists and dislocations in hBN crystals, but due to the highly anisotropic nature of hBN, their existence may be inevitable no matter the growth technique.
Cai, Jiaqi [Verfasser], and Carsten [Gutachter] Busse. "Monolayer hexagonal boron nitride: an ultra-thin insulator / Jiaqi Cai ; Gutachter: Carsten Busse." Siegen : Universitätsbibliothek der Universität Siegen, 2021. http://d-nb.info/1236754956/34.
Повний текст джерелаChan, Chit-yiu. "Nucleation and growth of cubic boron nitride thin films /." access full-text access abstract and table of contents, 2005. http://libweb.cityu.edu.hk/cgi-bin/ezdb/thesis.pl?phd-ap-b19887693a.pdf.
Повний текст джерела"Submitted to Department of Physics and Materials Science in partial fulfillment of the requirements for the degree of Doctor of Philosophy" Includes bibliographical references (leaves 147-154)
Law, Ka Cheong. "Temperature parameter at synthesis of cubic boron nitride films." access abstract and table of contents access full-text, 2005. http://libweb.cityu.edu.hk/cgi-bin/ezdb/dissert.pl?msc-ap-b21174477a.pdf.
Повний текст джерелаAt head of title: City University of Hong Kong, Department of Physics and Materials Science, Master of Science in materials engineering & nanotechnology dissertation. Title from title screen (viewed on Sept. 1, 2006) Includes bibliographical references.
Deyneka, Nataliya [Verfasser]. "Properties of nanocrystalline cubic boron nitride films / Nataliya Deyneka." Ulm : Universität Ulm. Fakultät für Naturwissenschaften, 2003. http://d-nb.info/1015354882/34.
Повний текст джерелаTodi, Vinit O. "Investigation of reactively sputtered boron carbon nitride thin films." Doctoral diss., University of Central Florida, 2011. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5069.
Повний текст джерелаID: 030422822; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Thesis (Ph.D.)--University of Central Florida, 2011.; Includes bibliographical references (p. 112-130).
Ph.D.
Doctorate
Electrical Engineering and Computer Science
Engineering and Computer Science
Fong, Tsz Wang. "Surface roughness parameter at synthesis of cubic boron nitride films." access abstract and table of contents access full-text, 2005. http://libweb.cityu.edu.hk/cgi-bin/ezdb/dissert.pl?msc-ap-b21174143a.pdf.
Повний текст джерелаAt head of title: City University of Hong Kong, Department of Physics and Materials Science, Master of Science in materials engineering & nanotechnology dissertation. Title from title screen (viewed on Aug. 31, 2006) Includes bibliographical references.
Maranon, Walter Nasrazadani Seifollah. "Characterization of boron nitride thin films on silicon (100) wafers." [Denton, Tex.] : University of North Texas, 2007. http://digital.library.unt.edu/permalink/meta-dc-3942.
Повний текст джерелаLorenzzi, Jean Carlos da Conceição. "Boron nitride thin films deposited by magnetron sputtering on Si3N4." Master's thesis, Universidade de Aveiro, 2007. http://hdl.handle.net/10773/2307.
Повний текст джерелаO Nitreto de boro é um material polimorfo, sendo as fases hexagonal (h-BN) ecúbicas (c-BN) as predominantes. A fase hexagonal do nitreto de boro apresenta uma estrutura em camadas sp2, semelhante a grafite, enquanto que a fase cúbica do nitreto de boro tem forte ligações sp3, como o diamante. O h- BN apresenta boas propriedades dieléctricas, é um material refractário, resistente a corrosão, é conhecido por ser um lubrificante sólido que tem aplicações na protecção de moldes de injecção e em outros processos mecânicos de elevadas temperaturas ou lubrificação em ambientes de elevada humidade. Contudo, o h-BN é extremamente macio. Em contraste, o c-BN apresenta excelentes propriedades térmicas, eléctricas e ópticas, sendo ainda um dos materiais conhecidos com dureza mais elevada (70 GPa). Além disso, c-BN apresenta propriedades superiores em relação ao diamante quando aplicado em ferramentas de corte na maquinagem de materiais ferrosos, devido a sua alta estabilidade química a altas temperaturas durante a maquinagem. Essa combinação de propriedades faz dele um forte candidato no campo das ferramentas de corte e em dipositivos electrónicos. No presente trabalho, filmes finos de nitreto de boro foram depositados por DC e RF magnetron sputtering, utilizando alvos de B4C e h-BN prensados a quente, numa atmosfera de deposição contituída por misturas de Ar e N2. Os filmes finos de BN foram depositados simultâneamente em dois tipos de substratos: cerâmicos de Si3N4 com diferentes acabamentos superficiais e em discos de Si(100). A influência dos parâmetros de deposição, tais como a temperatura do substrato, composição da atmosfera de deposição na espessura dos filmes, taxa de deposição, cristalinidade, tensão residual, fases presentes e dureza, foram sistematicamente investigados usando técnicas como, SEM, XRD, FT-IR e nanodureza. O h-BN foi a principal fase observada nas análises dos espectros de FT-IR e nos difractogramas de XRD. O estado de tensão dos filmes finos de BN films é estremamente afectado pela temperatura do substrato, composição do gás de trabalho e pelo acabamento superficial dos substratos. O estudo da influência da temperatura mostraram que a taxa de deposição aumenta com o aumento da temperatura do substrato. Tensões residuais elevadas ocorrem para altas concentrações de árgon e para substratos polidos em suspensão de diamante 15 μm. Nos espectros de FT-IR, a forma das bandas de vibração variam de uma forma alargada para uma configuração estreita, correspondendo a uma menor desordem da fase hexagonal do BN, devido a variação da composição da atmosfera de deposição. Os valores de dureza obtidos estão numa faixa que vai desde os valores do h-BN macio (6 GPa) até valores próximos dos limites encontrados para filmes contendo a fase cúbica (16 GPa ), acima de 40%. ABSTRACT: Boron nitride is a polymorphic material, the hexagonal (h-BN) and the cubic (c- BN) being its main crystalline structure. The hexagonal boron nitride has a layered sp2-bonded structure, similar to graphite, while the cubic boron nitride has a hard sp3-bonded diamond-like structure. h-BN presents good dielectric properties, refractoriness, corrosion-resistant characteristics, low friction and low wear rate, and it is a well-known solid lubricant which has wide applications in metal-forming dies and other metal working processes at high temperatures or lubrication in high relative humidity environments. However, h-BN is mechanically soft. In contrast, c-BN presents excellent thermal, electrical and optical properties, with a hardness up to 70 GPa. Moreover, c-BN is superior to diamond as cutting tool for ferrous materials due to its high thermal chemical stability during machining. In the present work, thin films of boron nitride have been deposited by D.C. and R.F. magnetron sputtering from hot-pressed B4C and h-BN targets, using mixtures of Ar and N2, as working gases. The BN thin films were deposited simultaneously on two different substrates: Si3N4 ceramics with different surface finishing and Si(100) wafers. The influence of parameters such as substrate temperature and working gas composition ratio, on film thickness, deposition rate, cristallinity, residual stress, phase composition and hardness, were systematically investigated using techniques like SEM, XRD, FT-IR and nanohardness. h-BN was the main observed phase. The stress-state of the thin BN films is largely affected by the substrate temperature, working gas composition and the substrate surface finishing. The substrate temperature studies show that the deposition rate increases with an increasing of the substrate temperature. Large high residual stresses are developed for higher argon ratios and for substrate finishing with 15 μm diamond paste. In the FT-IR spectra, the shape of the vibration band changes from broad to narrow, corresponding to a less disorder h-BN phase, due to the working gas composition. The hardness values obtained are typical in the range of a soft h-BN (6 GPa) to values approaching the limit of the range reported for films containing a fraction of cubic phase (16 GPa ) up to 40%.
Maranon, Walter. "Characterization of Boron Nitride Thin Films on Silicon (100) Wafer." Thesis, University of North Texas, 2007. https://digital.library.unt.edu/ark:/67531/metadc3942/.
Повний текст джерелаTararan, Anna. "Spectroscopy in fragile 2D materials : from Graphene Oxide to single molecules at hexagonal Boron Nitride." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLS441/document.
Повний текст джерелаElectron energy loss spectroscopy (EELS) and cathodoluminescence(CL) in a scanning transmission electron microscope (STEM) are extremely powerful techniques for the study of individual nanostructures. Nevertheless, fast electrons damage extremely sensitive thin specimens, imposing strong limitations on the spatial resolution and the intensity of spectroscopic measurements. During this thesis we have overcome this restriction by developing material-specific acquisition protocols for the study of some archetypical fragile nanosystems. In the first part of this thesis we have characterized graphene oxide (GO) and reduced graphene oxide (RGO) thin flakes by EELS spectroscopy in the STEM. Thanks to the particular setup of our microscope and by experimentally defining the optimal illumination conditions, we have derived oxygen quantification maps of (R)GO at an unprecedented spatial resolution. On the basis also of EELS fine structures analysis, we have revised the existing proposed atomic models for these materials. Another class of exceedingly sensitive nanometric systems is represented by individual molecules, which are strongly affected by both illumination and chemical/physical environment. We have performed the first CL-STEM investigation on the luminescence of isolated molecules, thanks to a watchful choice of the substrate. Hexagonal boron nitride (h-BN) is a flat, chemically inert 2D material, that actively takes part in the CL process by absorbing the incident energy. Excitation transfer from h-BN to molecules and the use of an innovative random scan acquisition routine in the STEM have allowed to considerably lower illumination effects and improve CL intensity. Afterwards, the attractive optical properties of h-BN have led to the study of its cubic phase (c-BN), which has been up to now hindered by the poor quality of the crystals. By EELS in the STEM we have analysed c-BN crystals of the highest available purity, identifying a wider optical band-gap with respect to previous experimental studies and in better agreement with recent calculations. In commercial crystals, several defect-related emissions have been identified and analysed in terms of characteristic energy, spatial distribution and lifetime using CL and Hanbury-Brown and Twiss intensity interferometry
Neumann, Christoph Malte [Verfasser], Christoph [Akademischer Betreuer] Stampfer, and Stephane [Akademischer Betreuer] Berciaud. "Raman Spectroscopy on Graphene Encapsulated in Hexagonal Boron Nitride / Christoph Malte Neumann ; Christoph Stampfer, Stephane Berciaud." Aachen : Universitätsbibliothek der RWTH Aachen, 2016. http://d-nb.info/1162498870/34.
Повний текст джерелаEyhusen, Sören. "Phase formation processes in the synthesis of boron nitride thin films." [S.l.] : [s.n.], 2005. http://webdoc.sub.gwdg.de/diss/2005/eyhusen.
Повний текст джерелаChan, Victory Tak Wah. "Temperature parameter at synthesis of cubic boron nitride films by chemical vapor desposition." access abstract and table of contents access full-text, 2005. http://libweb.cityu.edu.hk/cgi-bin/ezdb/dissert.pl?msc-ap-b21173989a.pdf.
Повний текст джерелаAt head of title: City University of Hong Kong, Department of Physics and Materials Science, Master of Science in materials engineering & nanotechnology dissertation. Title from title screen (viewed on Aug. 31, 2006) Includes bibliographical references.
Wickramasinghe, Thushan E. "Study of Impact Excitation Processes in Boron Nitride for Deep Ultra-Violet Electroluminescence Photonic Devices." Ohio University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1565311409028495.
Повний текст джерелаUddin, Md Salah. "Modeling of Hexagonal Boron Nitride Filled Bismalemide Polymer Composites for Thermal and Electrical Properties for Electronic Packaging." Thesis, University of North Texas, 2016. https://digital.library.unt.edu/ark:/67531/metadc955120/.
Повний текст джерелаHoffman, Timothy B. "Optimization and characterization of bulk hexagonal boron nitride single crystals grown by the nickel-chromium flux method." Diss., Kansas State University, 2016. http://hdl.handle.net/2097/32797.
Повний текст джерелаDepartment of Chemical Engineering
James H. Edgar
Hexagonal boron nitride (hBN) is a wide bandgap III-V semiconductor that has seen new interest due to the development of other III-V LED devices and the advent of graphene and other 2-D materials. For device applications, high quality, low defect density materials are needed. Several applications for hBN crystals are being investigated, including as a neutron detector and interference-less infrared-absorbing material. Isotopically enriched crystals were utilized for enhanced propagation of phonon modes. These applications exploit the unique physical, electronic and nanophotonics applications for bulk hBN crystals. In this study, bulk hBN crystals were grown by the flux method using a molten Ni-Cr solvent at high temperatures (1500°C) and atmospheric pressures. The effects of growth parameters, source materials, and gas environment on the crystals size, morphology and purity were established and controlled, and the reliability of the process was greatly improved. Single-crystal domains exceeding 1mm in width and 200μm in thickness were produced and transferred to handle substrates for analysis. Grain size dependence with respect to dwell temperature, cooling rate and cooling temperature were analyzed and modeled using response surface morphology. Most significantly, crystal grain width was predicted to increase linearly with dwell temperature, with single-crystal domains exceeding 2mm in at 1700°C. Isotopically enriched ¹⁰B and ¹¹B hBN crystal were produced using a Ni-Cr-B flux method, and their properties investigated. ¹⁰B concentration was evaluated using SIMS and correlated to the shift in the Raman peak of the E[subscript 2g] mode. Crystals with enrichment of 99% ¹⁰B and >99% ¹¹B were achieved, with corresponding Raman shift peaks at 1392.0 cm⁻¹ and 1356.6 cm⁻¹, respectively. Peak FWHM also decreased as isotopic enrichment approached 100%, with widths as low as 3.5 cm⁻¹ achieved, compared to 8.0 cm⁻¹ for natural abundance samples. Defect selective etching was performed using a molten NaOH-KOH etchant at 425°C-525°C, to quantify the quality of the crystals. Three etch pit shapes were identified and etch pit width was investigated as a function of temperature. Etch pit density and etch pit activation energy was estimated at 5×10⁷ cm⁻² and 60 kJ/mol, respectively. Screw and mixed-type dislocations were identified using diffraction-contrast TEM imaging.
Hao, Wenjun. "Atomic layer deposition of boron nitride." Thesis, Lyon, 2017. http://www.theses.fr/2017LYSE1311/document.
Повний текст джерелаThis thesis achieves 3 years of PhD studies on “Atomic layer deposition (ALD) of boron nitride (BN)”. The aim of this PhD work is to adapt the polymer derived ceramics (PDCs) route to the ALD technique for h-BN thin film growth and elaboration of functional nanostructures. A novel two-step ammonia-free ALD process, which includes ALD deposition of polyborazine at low temperature (80 °C) from 2,4,6-trichloroborazine and hexamethyldisilazane followed by post heat treatment under controlled atmosphere, has been established. Conformal and homogeneous BN thin films have been deposited onto various substrates. The self-limitation of the reactions on flat substrates and the conformality of the films on structured substrates have been verified. Functional BN nanostructures have thus been fabricated using substrates or templates with different dimensionalities. In particular, their applications as protective coatings as well as filter and absorber to purify polluted water from organic/oil hav e been investigated. Finally, a second low temperature (85-150 °C) ALD process using tri(isopropylamine)borane and methylamine as precursors has preliminary been studied in order to confirm the adaptability of PDCs route to ALD technique. BN thin films have been grown onto flat substrate and it has been proven that tri(isopropylamino)borane vapor can infiltrate into electrospun polyacrylonitrile fibers.This work was carried out at University of Lyon and financially supported by the National Research Agency (project n° ANR-16-CE08-0021-01)
Lung, Kai Chun. "Cubic boron nitride/nanodiamond composite films for the application in SAW devices." access abstract and table of contents access full-text, 2005. http://libweb.cityu.edu.hk/cgi-bin/ezdb/dissert.pl?msc-ap-b21175020a.pdf.
Повний текст джерелаAt head of title: City University of Hong Kong, Department of Physics and Materials Science, Master of Science in materials engineering & nanotechnology dissertation. Title from title screen (viewed on Sept. 4, 2006) Includes bibliographical references.
Vinogradov, Nikolay. "Controlling Electronic and Geometrical Structure of Honeycomb-Lattice Materials Supported on Metal Substrates : Graphene and Hexagonal Boron Nitride." Doctoral thesis, Uppsala universitet, Institutionen för fysik och astronomi, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-194089.
Повний текст джерелаAbendroth, Barbara. "Ion induced stress relaxation during the growth of cubic boron nitride thin films." Doctoral thesis, [S.l.] : [s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=972228373.
Повний текст джерелаAbendroth, B. "Ion-induced stress relaxation during the growth of cubic boron nitride thin films." Forschungszentrum Dresden, 2010. http://nbn-resolving.de/urn:nbn:de:bsz:d120-qucosa-28863.
Повний текст джерелаAbendroth, B. "Ion-induced stress relaxation during the growth of cubic boron nitride thin films." Forschungszentrum Rossendorf, 2004. https://hzdr.qucosa.de/id/qucosa%3A21713.
Повний текст джерелаChong, Yat Ming. "The study of cubic boron nitride/diamond composite films for sensing and mechanical applications /." access full-text access abstract and table of contents, 2009. http://libweb.cityu.edu.hk/cgi-bin/ezdb/thesis.pl?phd-ap-b23749003f.pdf.
Повний текст джерела"Submitted to Department of Physics and Materials Science in partial fulfillment of the requirements for the degree of Doctor of Philosophy." Includes bibliographical references (leaves 127-136)
Joshi, Sushobhan [Verfasser], Wilhelm [Akademischer Betreuer] [Gutachter] Auwärter, and Friedrich [Gutachter] Esch. "Hexagonal Boron Nitride Monolayers as Templates for Molecular Nanostructures / Sushobhan Joshi ; Gutachter: Friedrich Esch, Wilhelm Auwärter ; Betreuer: Wilhelm Auwärter." München : Universitätsbibliothek der TU München, 2017. http://d-nb.info/114382654X/34.
Повний текст джерелаPörtner, Mathias [Verfasser], Wilhelm [Akademischer Betreuer] Auwärter, Christine [Gutachter] Papadakis, and Wilhelm [Gutachter] Auwärter. "Adsorption of phthalocyanine-complexes on hexagonal boron nitride templates / Mathias Pörtner ; Gutachter: Christine Papadakis, Wilhelm Auwärter ; Betreuer: Wilhelm Auwärter." München : Universitätsbibliothek der TU München, 2020. http://d-nb.info/1205069585/34.
Повний текст джерелаLevert, Théo. "Growth and transfer of graphene and hexagonal boron nitride by chemical vapor deposition : applications to thermally efficient flexible electronics." Thesis, Lille 1, 2019. http://www.theses.fr/2019LIL1I007/document.
Повний текст джерелаA major challenge is to find a way to grow those materials in order to achieve an easy and economically attractive way to produce large area of those materials with a good quality. Another challenge is to transfer those materials on substrate compatible with electronics (mainly SiO2). We will focus the first part of our work on investigation of the growth conditions required to produce large area graphene and h-BN of good quality and their transfer on SiO2. Flexible electronics has become an important field of research for many applications, such as flexible batteries. In this goal, several materials have been used such as PEN, PET or polyimide (PI). All these materials present a good flexibility and a chemical compatibility with microelectronics process but they suffer from poor thermal conductivity, leading to lower utilization of power of devices deposited compared to classic microelectronic substrate such as SiO2. Several way have been recently investigated to bypass this problem and a good solution is to fill the matrix of the polymer or polyimide with nanomaterials or nanofillers. We choose to use graphene and h-BN as the filler in a 3D shape: a foam of graphene or h-BN as the nanofiller and we chose a PI as the matrix. In the second part, we will explain in details how we achieve novel flexible substrates with enhanced thermal properties. We succeed in producing polycrystalline graphene on copper with quite a good quality, fully covering the metallic substrate with a size of 2x2cm. We tried to grow monocrystalline graphene using standard CVD and achieved hexagonal single crystals of 30µm, which is quite small compared to other methods used in literature. We synthetized polycrystalline h-BN using copper as a catalyst and ammonia borane as the precursor with a size of 6x2cm with a good homogeneity on all available substrate. We were able to transfer both graphene an h-BN on Si02 substrate using both classical wet transfer and bubbling transfer, leading to a fastest transfer and resulting on clean transfer of our materials, free of cracks, bubbles and resist residues. We succeed in producing both 3D graphene and 3D h-BN as foam using a Nickel foam as the catalyst, resulting in multilayer graphene and h-BN with a good quality. We produced new flexible and thermal efficient substrates using these foams as a filler in a matrix of PI, already commonly used as a classical flexible substrate for microelectronics. We developed two generations of substrates. We found similar mechanical properties and thermal stability as the commercial Kapton. We deposited thermistors on the surface in order to study the thermal dissipation of our samples. We improved the maximum power applied on the thermistors up to 100% before breakdown