Download or read book Plasma Enhanced Gas Source Molecular Beam Epitaxy Deposition of High Quality GaN written by and published by . This book was released on 1990 with total page 17 pages. Available in PDF, EPUB and Kindle. Book excerpt: GaN is a III-V semiconductor with enormous optical device potential in the near ultraviolet region, a band which has been relatively inaccessible to semiconductor technology. High quality GaN, along with its A1N and InN alloys, would make feasible the production of optically active devices ranging from the visible out to the approximately 6 eV band gap of A1N. Along with its potential benefits come the challenges of this material system. Researchers in the past have been plagued by the inertness of nitrogen which causes GaN films to have a high n-type background carrier concentration resulting from nitrogen vacancies. The goal is to apply electron cyclotron resonance plasma and molecular beam epitaxy technology towards the GaN problem to obtain device quality semiconductor material. With the growth of high quality cubic GaN this past year, our program has defined itself into two main objectives. Further optimization of the GaN deposition to obtain material of the highest optical and electronic quality will be necessary. Parallel efforts will be undertaken in the related A1N and InN systems. The ability to grow each material will allow these materials to be combined into heterostructure devices analogous to those common in other compound semiconductor systems. A second avenue of activity which can be explored in parallel with the device work will be a cataloging of the properties of the entirely new cubic phases of GaN, InN and A1N. Cubic InN and A1N have never to our knowledge been produced in a laboratory. Comparison of the physical properties of these materials with the established properties of the wurtzite phases would yield interesting insights into the role of crystal structure and its influence on the solid state.

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1994 with total page 818 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Gas Source Molecular Beam Epitaxy written by Morton B. Panish and published by Springer Science & Business Media. This book was released on 2013-03-07 with total page 441 pages. Available in PDF, EPUB and Kindle. Book excerpt: The first book to present a unified treatment of hybrid source MBE and metalorganic MBE. Since metalorganic MBE permits selective area growth, the latest information on its application to the INP/GaInAs(P) system is presented. This system has been highlighted because it is one of rising importance, vital to optical communications systems, and has great potential for future ultra-highspeed electronics. The use of such analytical methods as high resolution x-ray diffraction, secondary ion mass spectroscopy, several photoluminescence methods, and the use of active devices for materials evaluation is shown in detail.

Download or read book Selected Energy Epitaxial Deposition and Low Energy Electron Microscopy of AlN GaN and SiC Thin Films written by and published by . This book was released on 1995 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt: As-received wafers of n- and p-type 6H-SiC(0001) were etched via gaseous HCl in H2 at 1350 deg C at NASA-Lewis to remove cutting and polishing scratches from the surface; however, etch pits were created. GaN films have been deposited on Si(100) and Al2O3(0001) substrates using triethylgallium and NH3 seeded into highly expanded He gas streams. A two-step deposition process that repeatedly resulted in continuous crystalline GaN films has been developed. The microstructure and composition of the resultant films were characterized by SEM, RHEED and AES and film character correlated to deposition conditions. Assembly of a new dual seeded beam deposition and film analysis facility is underway. In addition, the main chamber of a dual Colutron ion-beam deposition system for the deposition of high-quality SiC and GaN films is nearing completion. Ion sources have been assembled and leak-tested. Preliminary results on the characterization of a seeded supersonic molecular beam source are presented. A room temperature beam of 10% NH3 with a source pressure of 25 kTorr and a 25 micrometers nozzle produces NH3 molecules with mean energies of 0.264 eV and an energy spread of 0.068 eV. Modifications to the existing system are discussed.

Download or read book Molecular Beam Epitaxy written by Mohamed Henini and published by Elsevier. This book was released on 2018-06-27 with total page 790 pages. Available in PDF, EPUB and Kindle. Book excerpt: Molecular Beam Epitaxy (MBE): From Research to Mass Production, Second Edition, provides a comprehensive overview of the latest MBE research and applications in epitaxial growth, along with a detailed discussion and ‘how to’ on processing molecular or atomic beams that occur on the surface of a heated crystalline substrate in a vacuum. The techniques addressed in the book can be deployed wherever precise thin-film devices with enhanced and unique properties for computing, optics or photonics are required. It includes new semiconductor materials, new device structures that are commercially available, and many that are at the advanced research stage. This second edition covers the advances made by MBE, both in research and in the mass production of electronic and optoelectronic devices. Enhancements include new chapters on MBE growth of 2D materials, Si-Ge materials, AIN and GaN materials, and hybrid ferromagnet and semiconductor structures. Condenses the fundamental science of MBE into a modern reference, speeding up literature review Discusses new materials, novel applications and new device structures, grounding current commercial applications with modern understanding in industry and research Includes coverage of MBE as mass production epitaxial technology and how it enhances processing efficiency and throughput for the semiconductor industry and nanostructured semiconductor materials research community

Download or read book Molecular Beam Epitaxy Growth and Characerization of ZnO based layers and Heterostructures written by Abdelhamid Abdelrehim Mahmoud Elshaer and published by Cuvillier Verlag. This book was released on 2008-08-21 with total page 144 pages. Available in PDF, EPUB and Kindle. Book excerpt: In semiconductor research a reliable epitaxial growth technique for growing high quality thin films and heterostructures is necessary. In the case of ZnO one of the main difficulties is the absence of suitable substrate material for ZnO epitaxial growth. Although special oxide material (for example ScAlMgO4) and ZnO bulk crystal can serve as lattice matched substrates, the quality of the substrates themselves, the size of the available wafer, and the expense do not encourage to use these lattice matched substrates for ZnO epitaxial growth. In the current research, a widely used low cost commercial substrate sapphire was employed to develop a reliable epitaxial growth technique and growth process for ZnO. The versatile epitaxial growth technique, molecular beam epitaxy (MBE) equipped with a rf-plasma source was developed for growth and various characterizations methods were conducted to obtain a fundamental understanding in both the epitaxial processes and material properties of ZnO thin films and heterostructures. Employing a thin HT MgO buffer layer prior to ZnO growth is the key to overcome the very large mismatches between c-Al2O3 substrate. Wetting the surface of Al2O3 substrate with a few MgO monolayers, lowed the surface energy, so that the lateral growth of ZnO is promoted at the initial growth stage. MgO can be grown in the same chamber as ZnO without any contamination problem. These advantages make the growth procedure of a HT MgO buffer fast and easy. The growth temperature and the growth rate of MgO buffer are found to be important to improve the ZnO heteroepitaxy. An intermediate spinel layer in epitaxial relation with the sapphire substrate as well as with the HT MgO buffer layer is formed in the early stage of growth during the deposition of the MgO at 700°C. It was found that the combination of these two layers is useful for the progressive reduction of the ZnO overgrown with the sapphire substrate.Annealing experiments reveal that as soon as the spinel layer is formed at about 700°C, it remains stable at least up to 1000°C, and even it is extended in thickness. By recording and analyzing RHEED intensity oscillations, the growth kinetics has been investigated. Flat surface morphology and layer-by-layer growth has been achieved. The stoichiometry has been deduced by analyzing the growth rate as a function of Zn and O fluxes for various growth temperatures. It is found that the sticking coefficient of oxygen radicals is less dependent on the substrate temperature than that of Zn. The stoichiometric condition shifts to larger Zn flux at higher growth temperature. The kink rZnO values determine the activated O-flux supplied by the RF plasma source at TS=500°C, 400W and a given O2-flow rate. It equals 0.5±0.05 Ås-1 per sccm. Absolute αZn values versus TS, defined as αZn=rZnO(T)/rZnO(max), where rZnO(max) is recalculated from the Zn flux measured by a quartz monitor, using Zn/ZnO molar mass and density ratios. Ex-situ characterization of the grown ZnO layers indicate that the surface morphology and crystal quality of the ZnO films grown on sapphire by MBE using either oxygen plasma cell or H2O2 as an oxidant can be extensively improved by using an HT MgO buffer. ZnO layers reveal strong variation of surface morphology versus the O/Zn flux ratio. The most flat surface morphology of ZnO is obtained when the ratio is within the 0.7-1 range. The growth under O-rich conditions leads to formation of hexagonal pyramids and at higher O/Zn ratios to a 3D growth with the top layer formed by perfectly c-oriented columnar structures of 50-100 nm in a diameter. It was also possible to recover the initial 3D growth mode to the 2D one by employing the Zn-rich growth conditions at O/Zn=0.4-0.6. Structural characterizations by high resolution X-ray diffraction (HR-XRD) and transmission electron microscopy (TEM) indicate a dramatic reduction in defect density in the ZnO epilayers grown with an HT MgO buffer. By using TEM, it was found that the dominant extending defects are edge, screw and mixed-type dislocations along c-axis. The main defects were threading dislocations. This is resulted from the well controlled layer-by-layer growth, since only the edge-type dislocation is able to accommodate the lattice mismatch, while the screw type dislocation forms much related to the initial nucleation environment.The microstructure of ZnO epilayers has been studied by HR-XRD. The full width at half maximum of the (0002) reflection, 0.007 degree, is much smaller than that of the (10-10) reflection, 0.27 degree revealing the micro-twist dominates the mosaicity, while micro-tilt is much less important.This pronounced difference of the rocking curve widths between the (0002) and (1010) reflections strongly indicates that the density of pure edge threading dislocations is greater than that of pure screw dislocations. Optical characterizations reveal that exciton plays an important role in ZnO. At room temperature free exciton recombinations dominate the photoluminescence. The ZnO epilayers reveal well resolved low temperature PL excitonic spectra with a dominant bound exciton line (3.355 eV) possessing a ~2 meV half-width and a peak of free A exciton at 3.374 eV. The low-energy tail extending from the excitonic emission peaks due to the lattice deformation is significantly reduced, which allows the observation of two electron satellites and LO-phonons replicas of free and bound excitons. Variation of growth stoichiometry from O-rich to Zn-rich results in the pronounced quench of the acceptor-bound part of the excitonic band, as well as the strong intensity redistribution of donor-bound lines which seems to be attributed to a change in the point defect density. Temperature dependence of PL spectra between 6K and room temperature every 30 K under the same excitation conditions was performed. Slowly decreases coming at 300K to about one third of the intensity at 6K. This corresponds to the activation of non-radiative channels in the capturing and recombination processes. This result was confirm by decay time measurements. PL mapping of 2 inch ZnO epilayer shows high lateral homogeneity from PL intensity distribution and PL FWHM distribution. Hall-effect measurements and Electrochemical profiling (ECV) were used to characterize the electrical properties of ZnO samples. Hall-effect measurements indicated n-type behavior with carrier concentration of 2.0x1016 cm-3 and mobility of approximately 96 cm2/Vs. ECV profile versus depth measured for the top 2.5 μm thick sample gives surface carrier concentration is 2.0x1016 cm-3 increasing to a maximum value of 1.0x1018 cm-3 the semiconductor/substrate interface. P-n heterojuntions and mesa structures comprising MBE n-ZnO layers and CVD p-4H-SiC laser were manufactured and investigated. Electrical properties of the mesa diodes have been studied with Hall measurements, and current-voltage measurements (I-V). I-V measurements of the device show good rectifying behavior, from which a turn-on voltage of about 2 V was obtained. With the excitation of O and N gas mixture in a single plasma cell, followed by the sample annealing procedure. P-type ZnO:N layers with a net hole concentration 3x1017 cm-3 using was measured. The combination of low growth temperature, slightly O-rich conditions and post-growth annealing is shown to be effective way to obtain p-doping. Further efforts are necessary to improve structural quality of the low-temperature p-type ZnO:N films. Optical properties of ZnO based II-VI heterostructures and quantum structures have also been studied. The surface roughness of ZnxMg1−xO was as low as 0.7 nm. The optical band gap and photoluminescence peak can be turned to larger energy with the same high crystallinity and without significant change in the lattice constant. The prominent PL peaks related to the SQW show a systematic blueshift with decreasing well width, which is consistent with the quantum size effect. The SQW-related emission peaks exhibit an S-shaped (redshift-blueshiftredshift) behaviour with increasing temperature, which is in contrast with that ascribed to band gap shrinkage (redshift). The observed behavior is discussed in terms of localization at lateral interface potential fluctuations. For T >70 K the integrated PL intensity is thermally activated with activation energies much less than the band offsets. It is argued that the dominant mechanism leading to the quenching of the ZnO SQW-related PL is due to the thermionic emission of excitons out of the lateral potential minima caused by potential fluctuations, such as interface fluctuations by 1 ML. Stimulated emission has been achieved at room temperature in a separate confinement double heterostructure having a 3 nm wide SQW as an active region. It has been found that a critical parameter for the lasing is the inhomogeneous broadening of both QW and barrier emission bands. MBE process for ZnO has been developed where high quality ZnO epilayers and heterostructures can be grown by molecular beam epitaxy on sapphire substrate. For nitrogen doping of ZnO, Oxygen and nitrogen were activated in the single plasma cell. No reproducible and reliable experimental results on the achievement of p-type conductivity achieved. Stimulated emission has been achieved at room temperature.

Download or read book Performance Enhancement of GaN based High power Hemts by Selective area Growth Using Plasma assisted Molecular Beam Epitaxy written by Liang Pang and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book State of the Art Program on Compound Semiconductors XXXVI and Wide Bandgap Semiconductors for Photonic and Electronic Devices and Sensors II written by Electrochemical Society. Electronics Division and published by The Electrochemical Society. This book was released on 2002 with total page 380 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Molecular Beam Epitaxy written by Marian A. Herman and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 465 pages. Available in PDF, EPUB and Kindle. Book excerpt: Molecular Beam Epitaxy describes a technique in wide-spread use for the production of high-quality semiconductor devices. It discusses the most important aspects of the MBE apparatus, the physics and chemistry of the crystallization of various materials and device structures, and the characterization methods that relate the structural parameters of the grown (or growing) film or structure to the technologically relevant procedure. In this second edition two new fields have been added: crystallization of as-grown low-dimensional heterostructures, mainly quantum wires and quantum dots, and in-growth control of the MBE crystallization process of strained-layer structures. Out-of-date material has been removed.

Download or read book Laser Induced Damage in Optical Materials written by and published by . This book was released on 1995 with total page 744 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Japanese Journal of Applied Physics written by and published by . This book was released on 2000 with total page 712 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Handbook of Nitride Semiconductors and Devices Materials Properties Physics and Growth written by Hadis Morkoç and published by John Wiley & Sons. This book was released on 2009-07-30 with total page 1311 pages. Available in PDF, EPUB and Kindle. Book excerpt: The three volumes of this handbook treat the fundamentals, technology and nanotechnology of nitride semiconductors with an extraordinary clarity and depth. They present all the necessary basics of semiconductor and device physics and engineering together with an extensive reference section. Volume 1 deals with the properties and growth of GaN. The deposition methods considered are: hydride VPE, organometallic CVD, MBE, and liquid/high pressure growth. Additionally, extended defects and their electrical nature, point defects, and doping are reviewed.

Download or read book Nitrogen Compounds Advances in Research and Application 2013 Edition written by and published by ScholarlyEditions. This book was released on 2013-06-21 with total page 755 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nitrogen Compounds—Advances in Research and Application: 2013 Edition is a ScholarlyBrief™ that delivers timely, authoritative, comprehensive, and specialized information about ZZZAdditional Research in a concise format. The editors have built Nitrogen Compounds—Advances in Research and Application: 2013 Edition on the vast information databases of ScholarlyNews.™ You can expect the information about ZZZAdditional Research in this book to be deeper than what you can access anywhere else, as well as consistently reliable, authoritative, informed, and relevant. The content of Nitrogen Compounds—Advances in Research and Application: 2013 Edition has been produced by the world’s leading scientists, engineers, analysts, research institutions, and companies. All of the content is from peer-reviewed sources, and all of it is written, assembled, and edited by the editors at ScholarlyEditions™ and available exclusively from us. You now have a source you can cite with authority, confidence, and credibility. More information is available at http://www.ScholarlyEditions.com/.

Download or read book Chemical Abstracts written by and published by . This book was released on 2002 with total page 2668 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Oxide and Nitride Semiconductors written by Takafumi Yao and published by Springer Science & Business Media. This book was released on 2009-03-20 with total page 525 pages. Available in PDF, EPUB and Kindle. Book excerpt: This is a unique book devoted to the important class of both oxide and nitride semiconductors. It covers processing, properties and applications of ZnO and GaN. The aim of this book is to provide the fundamental and technological issues for both ZnO and GaN.

Download or read book Photoelectrochemical Water Splitting written by Hans-Joachim Lewerenz and published by Royal Society of Chemistry. This book was released on 2013-10-02 with total page 497 pages. Available in PDF, EPUB and Kindle. Book excerpt: There has been a resurgence of interest in light-induced water splitting as the search for storable carbon neutral energy becomes more urgent. Although the history of the basic idea dates back more than four decades, efficient, economical and stable integrated devices have yet to be realized. In the continuing quest for such devices, the field of photoelectrochemistry is entering a new phase where the extraordinary interdisciplinary of the research and development efforts are opening new avenues. This aspect of current research effort is reflected in the chapters of this book, which encompass present thinking in the various disciplines such as materials science, photo-electrochemistry and interfaces that can contribute to realization of viable solar fuel generators. This book presents a blend of the background science and recent advances in the field of photoelectrochemical water splitting, and includes aspects that point towards medium to long term future realization. The content of the book goes beyond the more traditional approaches to the subject by including topics such as novel excitation energy processes that have only been realized so far in advanced photonics. The comprehensive overview of current activities and development horizons provided by the impressive collection of internationally renowned authors therefore represents a unique reflection of current thinking regarding water splitting by light.

Download or read book Handbook of Crystal Growth written by Tom Kuech and published by Elsevier. This book was released on 2014-11-02 with total page 1384 pages. Available in PDF, EPUB and Kindle. Book excerpt: Volume IIIA Basic Techniques Handbook of Crystal Growth, Second Edition Volume IIIA (Basic Techniques), edited by chemical and biological engineering expert Thomas F. Kuech, presents the underpinning science and technology associated with epitaxial growth as well as highlighting many of the chief and burgeoning areas for epitaxial growth. Volume IIIA focuses on major growth techniques which are used both in the scientific investigation of crystal growth processes and commercial development of advanced epitaxial structures. Techniques based on vacuum deposition, vapor phase epitaxy, and liquid and solid phase epitaxy are presented along with new techniques for the development of three-dimensional nano-and micro-structures. Volume IIIB Materials, Processes, and Technology Handbook of Crystal Growth, Second Edition Volume IIIB (Materials, Processes, and Technology), edited by chemical and biological engineering expert Thomas F. Kuech, describes both specific techniques for epitaxial growth as well as an array of materials-specific growth processes. The volume begins by presenting variations on epitaxial growth process where the kinetic processes are used to develop new types of materials at low temperatures. Optical and physical characterizations of epitaxial films are discussed for both in situ and exit to characterization of epitaxial materials. The remainder of the volume presents both the epitaxial growth processes associated with key technology materials as well as unique structures such as monolayer and two dimensional materials. Volume IIIA Basic Techniques Provides an introduction to the chief epitaxial growth processes and the underpinning scientific concepts used to understand and develop new processes. Presents new techniques and technologies for the development of three-dimensional structures such as quantum dots, nano-wires, rods and patterned growth Introduces and utilizes basic concepts of thermodynamics, transport, and a wide cross-section of kinetic processes which form the atomic level text of growth process Volume IIIB Materials, Processes, and Technology Describes atomic level epitaxial deposition and other low temperature growth techniques Presents both the development of thermal and lattice mismatched streams as the techniques used to characterize the structural properties of these materials Presents in-depth discussion of the epitaxial growth techniques associated with silicone silicone-based materials, compound semiconductors, semiconducting nitrides, and refractory materials