Growth and Etching of Hexagonal Boron Nitride-control of Nucleation and Crystal Morphology PDF Download
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Author: Yanxin Ji
Publisher:
ISBN:
Category :
Languages : en
Pages : 80
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Book Description
Hexagonal boron nitride (h-BN) is a layered material and it is similar to graphene in lattice structure. Sheets of h-BN are composed of alternating boron and nitrogen atoms in a honeycomb arrangement. The strong bond between boron and nitrogen leads to the formation of a wide bandgap (5.9eV) material. The layers are held together by weak van der Waals forces as other layered materials. Since their superb chemical stability and intrinsic insulation, h-BN can be used as a thin top dielectric layer to gate graphene and as an inert substrate for graphene transistors. So the strategy to grow high quality h-BN on a large scale is very important. My research focuses on the controllable growth of h-BN on copper substrates using the low-pressure chemical vapor deposition (LPCVD) method. In order to optimize the growth condition, I investigated how the precursor, geometric environment, substrate engineering and gas mixture affect the quality of the as-grown h-BN. Electropolishing of the Cu substrate was used to reduce the nucleation density of h-BN and hence the domain sizes increase. The evolution of varied h-BN domain shapes was explained by the underlying growth mechanism. Raman, SEM, XPS, and LEEM I-V Curve were performed on the samples for characterization. In the last part, I will show the electric properties of the device made by the as-grown h-BN.
Author: Yanxin Ji
Publisher:
ISBN:
Category :
Languages : en
Pages : 80
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Book Description
Hexagonal boron nitride (h-BN) is a layered material and it is similar to graphene in lattice structure. Sheets of h-BN are composed of alternating boron and nitrogen atoms in a honeycomb arrangement. The strong bond between boron and nitrogen leads to the formation of a wide bandgap (5.9eV) material. The layers are held together by weak van der Waals forces as other layered materials. Since their superb chemical stability and intrinsic insulation, h-BN can be used as a thin top dielectric layer to gate graphene and as an inert substrate for graphene transistors. So the strategy to grow high quality h-BN on a large scale is very important. My research focuses on the controllable growth of h-BN on copper substrates using the low-pressure chemical vapor deposition (LPCVD) method. In order to optimize the growth condition, I investigated how the precursor, geometric environment, substrate engineering and gas mixture affect the quality of the as-grown h-BN. Electropolishing of the Cu substrate was used to reduce the nucleation density of h-BN and hence the domain sizes increase. The evolution of varied h-BN domain shapes was explained by the underlying growth mechanism. Raman, SEM, XPS, and LEEM I-V Curve were performed on the samples for characterization. In the last part, I will show the electric properties of the device made by the as-grown h-BN.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 7
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Book Description
Mono layer hexagonal boron nitride (hBN) attracts significant attention due to the potential to be used as a complementary two-dimensional dielectric in fabrication of functional 2D heterostructures. Here we investigate the growth stages of the hBN single crystals and show that hBN crystals change their shape from triangular to truncated triangular and further to hexagonal depending on copper substrate distance from the precursor. We suggest that the observed hBN crystal shape variation is affected by the ratio of boron to nitrogen active species concentrations on the copper surface inside the CVD reactor. Strong temperature dependence reveals the activation energies for the hBN nucleation process of similar to 5 eV and crystal growth of similar to 3.5 eV. We also show that the resulting h-BN film morphology is strongly affected by the heating method of borazane precursor and the buffer gas. Elucidation of these details facilitated synthesis of high quality large area monolayer hexagonal boron nitride by atmospheric pressure chemical vapor deposition on copper using borazane as a precursor.
Author: Roland Yingjie Tay
Publisher: Springer
ISBN: 9811088098
Category : Technology & Engineering
Languages : en
Pages : 152
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Book Description
This thesis focuses on the growth of a new type of two-dimensional (2D) material known as hexagonal boron nitride (h-BN) using chemical vapor deposition (CVD). It also presents several significant breakthroughs in the authors’ understanding of the growth mechanism and development of new growth techniques, which are now well known in the field. Of particular importance is the pioneering work showing experimental proof that 2D crystals of h-BN can indeed be hexagonal in shape. This came as a major surprise to many working in the 2D field, as it had been generally assumed that hexagonal-shaped h-BN was impossible due to energy dynamics. Beyond growth, the thesis also reports on synthesis techniques that are geared toward commercial applications. Large-area aligned growth and up to an eightfold reduction in the cost of h-BN production are demonstrated. At present, all other 2D materials generally use h-BN as their dielectric layer and for encapsulation. As such, this thesis lays the cornerstone for using CVD 2D h-BN for this purpose.
Author: Benjamin Clubine
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
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.
Author: Peter Michler
Publisher: Springer
ISBN: 3319563785
Category : Science
Languages : en
Pages : 457
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Book Description
This book highlights the most recent developments in quantum dot spin physics and the generation of deterministic superior non-classical light states with quantum dots. In particular, it addresses single quantum dot spin manipulation, spin-photon entanglement and the generation of single-photon and entangled photon pair states with nearly ideal properties. The role of semiconductor microcavities, nanophotonic interfaces as well as quantum photonic integrated circuits is emphasized. The latest theoretical and experimental studies of phonon-dressed light matter interaction, single-dot lasing and resonance fluorescence in QD cavity systems are also provided. The book is written by the leading experts in the field.
Author: Kalim Deshmukh
Publisher: Elsevier
ISBN: 0443188424
Category : Technology & Engineering
Languages : en
Pages : 668
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Book Description
Hexagonal Boron Nitride: Synthesis, Properties, and Applications offers a comprehensive approach to hexagonal boron nitride (h-BN), covering synthesis, exfoliation, properties, characterization, functionalization, heterostructures, nanocomposites, and modelling and simulation, and guiding the reader towards advanced applications in biomedicine, electronics, energy storage, wastewater treatment, and other areas.The book begins by introducing hexagonal boron nitride, discussing classification, structure, synthesis methods, exfoliation, and functionalization techniques. This is followed by in-depth coverage of properties and characterization, as well as heterostructures and other two-dimensional materials, as well as nanocomposites. The fourth section of the book examines specific target applications, covering a range of cutting-edge areas including micro- and nano-electronics, anti-friction and anti-corrosive coatings, bone tissue engineering, wound healing, nanomedicine, drug delivery, catalysis, water treatment, energy storage and conversion, sensing and bio-sensing, and fire-retardant applications. Finally, computational modelling and simulation, and environmental aspects, are addressed in detail.This is a valuable resource for researchers and advanced students across nanotechnology, materials science, chemistry, environmental science, chemical engineering, biomedicine, electronics, and engineering. In an industrial setting, this book supports scientists, engineers, and R&D professionals with an interest in advanced 2D materials or nanomaterials for advanced applications. - Presents the synthesis, properties, functionalization, and characterization methods for hexagonal boron nitride - Explores novel applications across biomedicine, electronics, energy storage, and water treatment - Addresses key challenges, such as biocompatibility, toxicity, and environmental and health impact
Author: Sachin Sharma
Publisher: Linköping University Electronic Press
ISBN: 9180755224
Category :
Languages : en
Pages : 81
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Book Description
Thin films of Boron Nitride (BN) and Boron Carbide (BC) possess properties that make them attractive for various applications. Epitaxially grown BN exhibits potential for optoelectronic devices, as piezoelectric materials, and graphene technology. Epitaxial BC is a semiconductor that could allow bandgap tuning and has potential applications in thermoelectric and optoelectronic devices. Both BN and BC material systems, generally deposited using chemical vapour deposition (CVD), are limited by the lack of control in depositing epitaxial films. In my thesis work, I have studied the evolution of various crystal phases of BN and BC and the factors that affect them during their CVD processes. I deposited and compared the growth of BN on Al2O3 (0001), (11 2 over bar 0), (1 1 over bar 02) and (10 1 over bar 0) substrates and used two organoboranes as boron precursors. Only Al2O3(11 2 over bar 0) and Al2O3 (0001) rendered crystalline films while the BN growth on the remaining substrates was X-ray amorphous. Furthermore, the less investigated Al2O3(11 2 over bar 0) had better crystalline quality versus the commonly used Al2O3 (0001). To further understand this, I studied crystalline BN thin films on an atomic scale and with a time evolution approach, uncovering the influence of carbon on hexagonal BN (h-BN). I showed that h-BN nucleates on both substrates but then either polytype transforms to rhombohedral-BN (r-BN) in stages, turns to less ordered turbostratic-BN or is terminated. An increase in local carbon content is the cause of these changes in epitaxial BN films during CVD. From the time evolution, we studied the effect of Al2O3 modification on h-BN nucleation during CVD. The interaction between boron and carbon during BN growth motivated studies also on the BxC materials. BxC was deposited using CVD at different temperatures on 4H-SiC(0001) (Si-face) and 4H-SiC(000 1 over bar) (C-face) substrates. Epitaxial rhombohedral-B4C (r-B4C) grew at 1300 °C on the C-face while the films deposited on the Si-face were polycrystalline. Comparing the initial nucleation layers on both 4H-SiC substrates on an atomic scale we showed that no interface phenomena are affecting epitaxial r-B4C growth conditions. We suggest that the difference in surface energy on the two substrate surfaces is the most plausible reason for the differences in epitaxial r-B4C growth conditions. In this thesis work, I identify the challenges and propose alternative routes to synthesise epitaxial BN and B4C materials using CVD. This fundamental materials science work enhances the understanding of growing these material systems epitaxially and in doing so furthers their development.
Author: Phaedon Avouris
Publisher: Cambridge University Press
ISBN: 1316738132
Category : Technology & Engineering
Languages : en
Pages : 521
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Book Description
Learn about the most recent advances in 2D materials with this comprehensive and accessible text. Providing all the necessary materials science and physics background, leading experts discuss the fundamental properties of a wide range of 2D materials, and their potential applications in electronic, optoelectronic and photonic devices. Several important classes of materials are covered, from more established ones such as graphene, hexagonal boron nitride, and transition metal dichalcogenides, to new and emerging materials such as black phosphorus, silicene, and germanene. Readers will gain an in-depth understanding of the electronic structure and optical, thermal, mechanical, vibrational, spin and plasmonic properties of each material, as well as the different techniques that can be used for their synthesis. Presenting a unified perspective on 2D materials, this is an excellent resource for graduate students, researchers and practitioners working in nanotechnology, nanoelectronics, nanophotonics, condensed matter physics, and chemistry.
Author: Dirk Ehrentraut
Publisher: Springer Science & Business Media
ISBN: 3642048307
Category : Science
Languages : en
Pages : 337
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Book Description
This book discusses the important technological aspects of the growth of GaN single crystals by HVPE, MOCVD, ammonothermal and flux methods for the purpose of free-standing GaN wafer production.
Author: Tim Hoffman
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
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 200[mu]m 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.
