DOCSLIB.ORG

Chemical Vapor Deposition of Heteroepitaxial Boron Phosphide Thin Films

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Chemical Vapor Deposition of Heteroepitaxial Boron Phosphide Thin Films University of Tennessee, Knoxville TRACE: Tennessee Research and Creative Exchange Doctoral Dissertations Graduate School 12-2013 Chemical Vapor Deposition of Heteroepitaxial Boron Phosphide Thin Films John Daniel Brasfield University of Tennessee - Knoxville, [email protected] Follow this and additional works at: https://trace.tennessee.edu/utk_graddiss Part of the Semiconductor and Optical Materials Commons Recommended Citation Brasfield, John Daniel, "Chemical aporV Deposition of Heteroepitaxial Boron Phosphide Thin Films. " PhD diss., University of Tennessee, 2013. https://trace.tennessee.edu/utk_graddiss/2558 This Dissertation is brought to you for free and open access by the Graduate School at TRACE: Tennessee Research and Creative Exchange. It has been accepted for inclusion in Doctoral Dissertations by an authorized administrator of TRACE: Tennessee Research and Creative Exchange. For more information, please contact [email protected]. To the Graduate Council: I am submitting herewith a dissertation written by John Daniel Brasfield entitled "Chemical Vapor Deposition of Heteroepitaxial Boron Phosphide Thin Films." I have examined the final electronic copy of this dissertation for form and content and recommend that it be accepted in partial fulfillment of the equirr ements for the degree of Doctor of Philosophy, with a major in Chemistry. Charles S. Feigerle, Major Professor We have read this dissertation and recommend its acceptance: Laurence Miller, Frank Vogt, Ziling Xue Accepted for the Council: Carolyn R. Hodges Vice Provost and Dean of the Graduate School (Original signatures are on file with official studentecor r ds.) Chemical Vapor Deposition of Heteroepitaxial Boron Phosphide Thin Films A Dissertation Presented for the Doctor of Philosophy Degree The University of Tennessee, Knoxville John Daniel Brasfield December 2013 Copyright © 2013 by John Daniel Brasfield All rights reserved. ii DEDICATION To my Family, Chase, Macie, and Hadley. For support and encouragement throughout this process… iii ACKNOWLEDGEMENTS This dissertation would not have been possible without a number of individuals each contributing in their own unique way. First, I would like to thank Dr. Feigerle for your patience, guidance and tutelage throughout the process. Your calm approach to problem solving has taught me that success takes time and is worth the wait. I would also like to thank Dr. Miller agreeing to serve on my committee. I would like to acknowledge the rest my committee members, Dr. Xue and Dr. Vogt for taking time to be a part of this research. Additional thanks goes to the supportive members of my research group. Thank you, Dr. Julia Abbott for toiling away in the lab and for the invaluable XRD analysis that shaped the project. Thank you to Eric Barrowclough for his work with Autocad and never ending encouragement and Stephen Gibson for his Mass Spectroscopy of weirdness of the process. Thanks to Alexis Dale for her dedication and courage to take on the this project. I would also like to thank my project collaborators in the Materials Science and Engineering Department for their research support. Many thanks to Dr. Gerd Duscher and Guloinag Li for their spectacular TEM analysis. Without out the wonderful images, progress would not have been possible. Acknowledgements go to Dr. Joo Hyon Noh for fabrication of the heterostructures and Dr. Eric Lukosi for useful consultation. From Y-12, thanks to Dr. Jonathan Morrell for your support and encouragement to pursue this degree. Many thanks to the rest of the members from the Compatibility and Surveillance section for their kindness and willingness to help when needed. Thanks to the Y-12 PDRD program for financial support of this project. My family played an integral role in my willingness to pursue a Ph.D. Thanks to my wife Chase for pushing me to work hard and get this done. Without you by my side, this would not have been accomplished. Thanks to my parents Robert and Judy Brasfield for teaching me the value of hard work and fostering a lifetime love of learning, to you both I am forever grateful. I would like to thank David Beach for his scientific guidance throughout this process. You were always there to answer the tough questions and point me in the right direction. Thanks for the support and believing that I could succeed in novel materials research. Finally, I would like to thank the DOE office of Nonproliferation Verification and Research for funding my research at Y-12 and the University of Tennessee for the past five years. iv ABSTRACT Boron monophosphide (BP) is a group III-V compound semiconductor with a wide band gap of 2.3 eV. Its unique electrical properties make it a promising material for use as a room temperature thermal neutron detector and thermoelectric device in high temperature and radiation fields. A thin film of BP enriched in the boron- 10 isotope can yield 2.8MeV of energy, which in solid- state BP can yield 0.5 million electron-hole pairs that would be detectable with minimal amplification in a device. The high carrier concentration, wide band gap, inertness and refractory nature make it an attractive∼ material for use in the extreme environments of nuclear reactors. The main drawback to BP is the difficulty in synthesizing high quality thin films. The majority of the previous work on BP was performed on Si substrates. The high lattice mismatch between Si and BP incorporates strain in the BP film which causes varying defects and charge traps to be introduced, adversely affecting electrical performance. It is the purpose of this work to identify the parameters necessary to deposit highly ordered zincblende boron phosphide (BP) thin films on 4° off-axis C-face 4H-SiC(0001) substrates by chemical vapor deposition. SiC only has a 4% lattice mismatch from BP, which could greatly reduce the inherent strain from heteroepitaxial growth. Ultra high purity diborane and phosphine are used as reactive precursors, with hydrogen as the carrier gas. Conditions necessary for high quality BP thin films will be explored. SEM, XRD, TEM and Raman spectroscopy are used to characterize the BP films and identify the temperature, phosphine to diborane flow rate ratios, SiC wafer termination and wafer surface preparation to elucidate optimum BP thin films for eventual device fabrication. v TABLE OF CONTENTS CHAPTER I Introduction ................................................................................................... 1 Semiconductors ............................................................................................................... 1 Boron Phosphide ............................................................................................................. 9 Physical Characteristics .............................................................................................. 9 Chemical Characteristics .......................................................................................... 12 Semiconductor Behavior ........................................................................................... 12 Early Synthesis.......................................................................................................... 13 Modern Synthesis...................................................................................................... 14 Applications of Boron Phosphide ................................................................................. 18 Neutron Detectors ..................................................................................................... 18 IR Coatings ............................................................................................................... 22 Thermoelectric Devices ............................................................................................ 23 Substrate Selection ........................................................................................................ 28 Silicon ....................................................................................................................... 29 Silicon Carbide.......................................................................................................... 32 Wafers ....................................................................................................................... 38 Summary ................................................................................................................... 41 CHAPTER II Reactor Design ........................................................................................... 43 Background ................................................................................................................... 43 CVD Reactor Components ........................................................................................... 46 Vacuum System, Components and Pumping ............................................................ 48 Gas Handling, Flow and Pressure Control ................................................................ 52 RF Heating and Susceptor Design ............................................................................ 60 Susceptor Temperature Measurement ....................................................................... 68 Safety Measures ........................................................................................................ 72 Function Testing ....................................................................................................... 79 BP Characterization Techniques ..................................................................................
Load more

Recommended publications
  • TR-499: Indium Phosphide (CASRN 22398-80-7) in F344/N Rats And
    NTP TECHNICAL REPORT ON THE TOXICOLOGY AND CARCINOGENESIS STUDIES OF INDIUM PHOSPHIDE (CAS NO. 22398-80-7) IN F344/N RATS AND B6C3F1 MICE (INHALATION STUDIES) NATIONAL TOXICOLOGY PROGRAM P.O. Box 12233 Research Triangle Park, NC 27709 July 2001 NTP TR 499 NIH Publication No. 01-4433 U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES Public Health Service National Institutes of Health FOREWORD The National Toxicology Program (NTP) is made up of four charter agencies of the U.S. Department of Health and Human Services (DHHS): the National Cancer Institute (NCI), National Institutes of Health; the National Institute of Environmental Health Sciences (NIEHS), National Institutes of Health; the National Center for Toxicological Research (NCTR), Food and Drug Administration; and the National Institute for Occupational Safety and Health (NIOSH), Centers for Disease Control and Prevention. In July 1981, the Carcinogenesis Bioassay Testing Program, NCI, was transferred to the NIEHS. The NTP coordinates the relevant programs, staff, and resources from these Public Health Service agencies relating to basic and applied research and to biological assay development and validation. The NTP develops, evaluates, and disseminates scientific information about potentially toxic and hazardous chemicals. This knowledge is used for protecting the health of the American people and for the primary prevention of disease. The studies described in this Technical Report were performed under the direction of the NIEHS and were conducted in compliance with NTP laboratory health and safety requirements and must meet or exceed all applicable federal, state, and local health and safety regulations. Animal care and use were in accordance with the Public Health Service Policy on Humane Care and Use of Animals.
    [Show full text]
  • Transition Metal Phosphides for the Catalytic Hydrodeoxygenation of Waste Oils Into Green Diesel
    catalysts Review Transition Metal Phosphides for the Catalytic Hydrodeoxygenation of Waste Oils into Green Diesel M. Consuelo Alvarez-Galvan * , Jose M. Campos-Martin * and Jose L. G. Fierro * Energy and Sustainable Chemistry Group (EQS), Instituto de Catálisis y Petroleoquímica, CSIC, c/Marie Curie, 2 Cantoblanco, 28049 Madrid, Spain * Correspondence: [email protected] (M.C.A.-G.); [email protected] (J.M.C.-M.); jlgfi[email protected] (J.L.G.F.) Received: 28 February 2019; Accepted: 15 March 2019; Published: 22 March 2019 Abstract: Recently, catalysts based on transition metal phosphides (TMPs) have attracted increasing interest for their use in hydrodeoxygenation (HDO) processes destined to synthesize biofuels (green or renewable diesel) from waste vegetable oils and fats (known as hydrotreated vegetable oils (HVO)), or from bio-oils. This fossil-free diesel product is produced completely from renewable raw materials with exceptional quality. These efficient HDO catalysts present electronic properties similar to noble metals, are cost-efficient, and are more stable and resistant to the presence of water than other classical catalytic formulations used for hydrotreatment reactions based on transition metal sulfides, but they do not require the continuous supply of a sulfide source. TMPs develop a bifunctional character (metallic and acidic) and present tunable catalytic properties related to the metal type, phosphorous-metal ratio, support nature, texture properties, and so on. Here, the recent progress in TMP-based catalysts for HDO of waste oils is reviewed. First, the use of TMPs in catalysis is addressed; then, the general aspects of green diesel (from bio-oils or from waste vegetable oils and fats) production by HDO of nonedible oil compounds are presented; and, finally, we attempt to describe the main advances in the development of catalysts based on TMPs for HDO, with an emphasis on the influence of the nature of active phases and effects of phosphorous, promoters, and preparation methods on reactivity.
    [Show full text]
  • Binary and Ternary Transition-Metal Phosphides As Hydrodenitrogenation Catalysts
    Research Collection Doctoral Thesis Binary and ternary transition-metal phosphides as hydrodenitrogenation catalysts Author(s): Stinner, Christoph Publication Date: 2001 Permanent Link: https://doi.org/10.3929/ethz-a-004378279 Rights / License: In Copyright - Non-Commercial Use Permitted This page was generated automatically upon download from the ETH Zurich Research Collection. For more information please consult the Terms of use. ETH Library Diss. ETH No. 14422 Binary and Ternary Transition-Metal Phosphides as Hydrodenitrogenation Catalysts A dissertation submitted to the Swiss Federal Institute of Technology Zurich for the degree of Doctor of Natural Sciences Presented by Christoph Stinner Dipl.-Chem. University of Bonn born February 27, 1969 in Troisdorf (NRW), Germany Accepted on the recommendation of Prof. Dr. Roel Prins, examiner Prof. Dr. Reinhard Nesper, co-examiner Dr. Thomas Weber, co-examiner Zurich 2001 I Contents Zusammenfassung V Abstract IX 1 Introduction 1 1.1 Motivation 1 1.2 Phosphides 4 1.2.1 General 4 1.2.2 Classification 4 1.2.3 Preparation 5 1.2.4 Properties 12 1.2.5 Applications and Uses 13 1.3 Scope of the Thesis 14 1.4 References 16 2 Characterization Methods 1 2.1 FT Raman Spectroscopy 21 2.2 Thermogravimetric Analysis 24 2.3 Temperature-Programmed Reduction 25 2.4 X-Ray Powder Diffractometry 26 2.5 Nitrogen Adsorption 28 2.6 Solid State Nuclear Magnetic Resonance Spectroscopy 28 2.7 Catalytic Test 33 2.8 References 36 3 Formation, Structure, and HDN Activity of Unsupported Molybdenum Phosphide 37 3.1 Introduction
    [Show full text]
  • Subject Index
    SUBJECT INDEX Vol. 1: 1–698, Vol. 2: 699–1395, Vol. 3: 1397–2111, Vol. 4: 2113–2798, Vol. 5: 2799–3440. Page numbers suffixed by t and f refer to Tables and Figures respectively. Absorption spectra in aqueous solution, 752–770 of americium, 1364–1368 compounds of, 721–752 americium (III), 1364–1365, 1365f coordination complexes in solution, americium (IV), 1365 771–782 americium (V), 1366, 1367f history of, 699–700 americium (VI), 1366, 1367f isotope production, 702–703 americium (VII), 1367–1368, 1368f metallic state of, 717–721 of liquid plutonium, 963 in nature, 703–704 of neptunium, 763–766, 763f, 786–787 nuclear properties of, 700–702 neptunium (VII) ternary oxides, 729 separation and purification, 704–717 of plutonium plutonium hexafluoride, 1088, 1089f atomic properties of, 857–862 ions, 1113–1117, 1116t compounds of, 987–1108 plutonium (IV), 849 metal and intermetallic compounds of, polymerization, 1151, 1151f 862–987 tetrachloride, 1093–1094, 1094f natural occurrence of, 822–824 tribromide, 1099t, 1100 nuclear properties of, 815–822 trichloride, 1099, 1099t separation and purification of, 826–857 Accelerator mass spectrometry (AMS), of solution chemistry of, 1108–1203 neptunium, 790 Actinide elements Acetates atomic volumes of, 922–923, 923f of americium, 1322, 1323t extraction of of plutonium, 1177, 1180 DIDPA, 1276 Acetone, derived compounds, of americium, HDEHP, 1275 1322, 1323t, 1324 organophosphorus and Acids carbamoylphosphonate reagents, for Purex process, 711 1276–1278 for solvent extraction, 839 stripping of, 1280–1281 Actinide
    [Show full text]
  • Organometallic Pnictogen Chemistry
    Institut für Anorganische Chemie 2014 Fakultät für Chemie und Pharmazie | Sabine Reisinger aus Regensburg, geb. Scheuermayer am 15.07.1983 Studium: Chemie, Universität Regensburg Abschluss: Diplom Promotion: Prof. Dr. Manfred Scheer, Institut für Anorganische Chemie Sabine Reisinger Die vorliegende Arbeit enthält drei Kapitel zu unterschiedlichen Aspekten der metallorganischen Phosphor- und Arsen-Chemie. Zunächst werden Beiträge zur supramolekularen Chemie mit 5 Pn-Ligandkomplexen basierend auf [Cp*Fe(η -P5)] und 5 i [Cp*Fe(η - Pr3C3P2)] gezeigt, gefolgt von der Eisen-vermittelten Organometallic Pnictogen Aktivierung von P4, die zu einer selektiven C–P-Bindungsknüpfung führt, während das dritte Kapitel die Verwendung von Phosphor Chemistry – Three Aspects und Arsen als Donoratome in mehrkernigen Komplexen mit paramagnetischen Metallionen behandelt. Sabine Reisinger 2014 Alumniverein Chemie der Universität Regensburg E.V. [email protected] http://www.alumnichemie-uniregensburg.de Aspects Three – Chemistry Pnictogen Organometallic Fakultät für Chemie und Pharmazie ISBN 978-3-86845-118-4 Universität Regensburg Universitätsstraße 31 93053 Regensburg www.uni-regensburg.de 9 783868 451184 4 Sabine Reisinger Organometallic Pnictogen Chemistry – Three Aspects Organometallic Pnictogen Chemistry – Three Aspects Dissertation zur Erlangung des Doktorgrades der Naturwissenschaften (Dr. rer. nat.) der Fakultät für Chemie und Pharmazie der Universität Regensburg vorgelegt von Sabine Reisinger, geb. Scheuermayer Regensburg 2014 Die Arbeit wurde von Prof. Dr. Manfred Scheer angeleitet. Das Promotionsgesuch wurde am 20.06.2014 eingereicht. Das Kolloquium fand am 11.07.2014 statt. Prüfungsausschuss: Vorsitzender: Prof. Dr. Helmut Motschmann 1. Gutachter: Prof. Dr. Manfred Scheer 2. Gutachter: Prof. Dr. Henri Brunner weiterer Prüfer: Prof. Dr. Bernhard Dick Dissertationsreihe der Fakultät für Chemie und Pharmazie der Universität Regensburg, Band 4 Herausgegeben vom Alumniverein Chemie der Universität Regensburg e.V.
    [Show full text]
  • Chemical Names and CAS Numbers Final
    Chemical Abstract Chemical Formula Chemical Name Service (CAS) Number C3H8O 1‐propanol C4H7BrO2 2‐bromobutyric acid 80‐58‐0 GeH3COOH 2‐germaacetic acid C4H10 2‐methylpropane 75‐28‐5 C3H8O 2‐propanol 67‐63‐0 C6H10O3 4‐acetylbutyric acid 448671 C4H7BrO2 4‐bromobutyric acid 2623‐87‐2 CH3CHO acetaldehyde CH3CONH2 acetamide C8H9NO2 acetaminophen 103‐90‐2 − C2H3O2 acetate ion − CH3COO acetate ion C2H4O2 acetic acid 64‐19‐7 CH3COOH acetic acid (CH3)2CO acetone CH3COCl acetyl chloride C2H2 acetylene 74‐86‐2 HCCH acetylene C9H8O4 acetylsalicylic acid 50‐78‐2 H2C(CH)CN acrylonitrile C3H7NO2 Ala C3H7NO2 alanine 56‐41‐7 NaAlSi3O3 albite AlSb aluminium antimonide 25152‐52‐7 AlAs aluminium arsenide 22831‐42‐1 AlBO2 aluminium borate 61279‐70‐7 AlBO aluminium boron oxide 12041‐48‐4 AlBr3 aluminium bromide 7727‐15‐3 AlBr3•6H2O aluminium bromide hexahydrate 2149397 AlCl4Cs aluminium caesium tetrachloride 17992‐03‐9 AlCl3 aluminium chloride (anhydrous) 7446‐70‐0 AlCl3•6H2O aluminium chloride hexahydrate 7784‐13‐6 AlClO aluminium chloride oxide 13596‐11‐7 AlB2 aluminium diboride 12041‐50‐8 AlF2 aluminium difluoride 13569‐23‐8 AlF2O aluminium difluoride oxide 38344‐66‐0 AlB12 aluminium dodecaboride 12041‐54‐2 Al2F6 aluminium fluoride 17949‐86‐9 AlF3 aluminium fluoride 7784‐18‐1 Al(CHO2)3 aluminium formate 7360‐53‐4 1 of 75 Chemical Abstract Chemical Formula Chemical Name Service (CAS) Number Al(OH)3 aluminium hydroxide 21645‐51‐2 Al2I6 aluminium iodide 18898‐35‐6 AlI3 aluminium iodide 7784‐23‐8 AlBr aluminium monobromide 22359‐97‐3 AlCl aluminium monochloride
    [Show full text]
  • Agricultural Commodity Protection by Phosphine Fumigation: Programmatic Environmental Assessment Tools Annex
    AGRICULTURAL COMMODITY PROTECTION BY PHOSPHINE FUMIGATION PROGRAMMATIC ENVIRONMENTAL ASSESSMENT TOOLS ANNEX NOVEMBER 2013 This publication was produced for review by the United States Agency for International Development (USAID). It was prepared under USAID’s Global Environmental Management Support (GEMS) project. Cover photos: Phosphine fumigation monitoring equipment (top left), DIMEGSA Pest Control staff in Guatemala (top right), USAID food commodities stored in a warehouse (bottom). COMMODITY PROTECTION BY PHOSPHINE FUMIGATION IN USAID FOOD AID PROGRAMS PROGRAMMATIC ENVIRONMENTAL ASSESSMENT TOOLS ANNEX Updated December 2015 (original NOVEMBER 2013) Contract No.: AID-OAA-M-11-00021 Prepared for: Office of Food for Peace Bureau for Democracy, Conflict and Humanitarian Assistance United States Agency for International Development Prepared under: The Global Environmental Management Support Project (GEMS), Award Number AID-OAA-M-11-00021. The Cadmus Group, Inc., prime contractor (www.cadmusgroup.com). Sun Mountain International, principal partner (www.smtn.org). DISCLAIMER Until and unless this document is approved by USAID as a 22 CFR 216 Programmatic Environmental Assessment, the contents may not necessarily reflect the views of the United States Agency for International Development or the United States Government. TABLE OF CONTENTS ANNEX T-1: GUIDE: FUMIGATION COMPLIANCE GUIDANCE FOR USAID PARTNERS…..…….1 ANNEX T-2: TEMPLATE: FOOD COMMODITY PROTECTION PERSUAP FOR PHOSPHINE FUMIGATION & CONTACT PESTICIDES…………………………………………………..…………4 ANNEX
    [Show full text]
  • WP934SA/IYGD5V T-1 (3Mm) Tri-Level Circuit Board Indicator
    WP934SA/IYGD5V T-1 (3mm) Tri-Level Circuit Board Indicator DESCRIPTIONS PACKAGE DIMENSIONS The High Efficiency Red source color devices are LED1 : Red made with Gallium Arsenide Phosphide on Gallium LED2 : Yellow Phosphide Orange Light Emitting Diode LED3 : Green The Yellow source color devices are made with Gallium Arsenide Phosphide on Gallium Phosphide Yellow Light Emitting Diode The Green source color devices are made with Gallium Phosphide Green Light Emitting Diode Electrostatic discharge and power surge could damage the LEDs It is recommended to use a wrist band or anti-electrostatic glove when handling the LEDs All devices, equipments and machineries must be electrically grounded FEATURES Pre-trimmed leads for pc mounting Black case enhances contrast ratio High reliability life measured in years Housing UL rating: 94V-0 Housing material: Type 66 nylon 5V internal resistor RoHS compliant APPLICATIONS Notes: 1. All dimensions are in millimeters (inches). Status indicator 2. Tolerance is ±0.25(0.01") unless otherwise noted. 3. Lead spacing is measured where the leads emerge from the package. Illuminator 4. The specifications, characteristics and technical data described in the datasheet are subject to change without prior notice. Signage applications Decorative and entertainment lighting Commercial and residential architectural lighting ATTENTION Observe precautions for handling electrostatic discharge sensitive devices SELECTION GUIDE Iv (mcd) V = 5V [2] Viewing Angle [1] Emitting Color Part Number Lens Type (Material) Min. Typ. 2θ1/2 12 25 ■ High Efficiency Red Red Diffused 50° (GaAsP/GaP) *6 *14 7 15 WP934SA/IYGD5V ■ Yellow (GaAsP/GaP) Yellow Diffused 50° *7 *15 12 25 ■ Green (GaP) Green Diffused 50° *12 *25 Notes: 1.
    [Show full text]
  • The Use of Aluminum Phosphide in Wildlife Damage Management
    Human Health and Ecological Risk Assessment for the Use of Wildlife Damage Management Methods by USDA-APHIS-Wildlife Services Chapter IX The Use of Aluminum Phosphide in Wildlife Damage Management July 2017 Peer Reviewed Final March 2020 THE USE OF ALUMINUM PHOSPHIDE IN WILDLIFE DAMAGE MANAGEMENT EXECUTIVE SUMMARY Aluminum phosphide is a fumigant used by USDA-APHIS-Wildlife Services (WS) to control various burrowing rodents and moles. Formulations for burrow treatments are in 3-g tablets or 600-mg pellets containing about 56% active ingredient. WS applicators place the tablets or pellets into the target species’ burrow and seal the burrow entrance with soil. Aluminum phosphide reacts with moisture in burrows to release phosphine gas, which is the toxin in the fumigant. WS applicators used aluminum phosphide to take 19 species of rodents and moles between FY11 and FY15 and treated an annual average of including prairie dogs, ground squirrels, pocket gophers, voles, and moles. WS annually averaged the known take of 54,095 target rodents and an estimated 2,333 vertebrate nontarget species with aluminum phosphide in 9 states. An average of 58,329 burrows was treated with the primary target species being black-tailed and Gunnison’s prairie dogs. APHIS evaluated the human health and ecological risk of aluminum phosphide under the WS use pattern for rodent and mole control. Although phosphine gas is toxic to humans, the risk to human health is low because inhalation exposure is slight for the underground applications. WS applicators wear proper personal protective equipment according to the pesticide label requirements, which reduces their exposure to aluminum phosphide and phosphine gas, and lowers the risk to their health.
    [Show full text]
  • LED) Materials and Challenges- a Brief Review
    6 IV April 2018 http://doi.org/10.22214/ijraset.2018.4723 International Journal for Research in Applied Science & Engineering Technology (IJRASET) ISSN: 2321-9653; IC Value: 45.98; SJ Impact Factor: 6.887 Volume 6 Issue IV, April 2018- Available at www.ijraset.com Different Types of in Light Emitting Diodes (LED) Materials and Challenges- A Brief Review BY Susan John1 1Dept Of Physics S. F. S College Nagpur 06, Maharashtra State. India I. INTRODUCTION LEDs are semiconductor devices, which produce light when current flows through them. It is a two-lead semiconductor light source. It is a p–n junction diode that emits light when activated. When a suitable current is applied electrons are able to recombine with electron holes within the device, releasing energy in the form of photons. This effect is called electroluminescence, and the color of the light is determined by the energy band gap of the semiconductor. LEDs are typically very small. In order to improve the efficiency many researches in LEDs and its phosphor has been taking place. However still many technical challenges such as conversion losses, color control, current efficiency droop, color shift, system reliability as well as in light distribution, dimming, thermal management and driver power supply performances etc need to be met in order to achieve low cost and high efficiency. [1] Keywords: Glare, blue hazard and semiconductor. I. DIFFERENT TYPES OF LEDS MATERIALS USED: A. Gallium Arsenide (GaAs) emits infra-red light B. Gallium Arsenide Phosphide (GaAsP) emits red to infra-red, orange light C. Gallium Phosphide (GaP) emits red, yellow and green light D.
    [Show full text]
  • Synthesis and Characterization of Diamond and Boron Phosphide
    University of Rhode Island DigitalCommons@URI Open Access Dissertations 1972 Synthesis and Characterization of Diamond and Boron Phosphide K. P. Ananthanarayanan University of Rhode Island Follow this and additional works at: https://digitalcommons.uri.edu/oa_diss Recommended Citation Ananthanarayanan, K. P., "Synthesis and Characterization of Diamond and Boron Phosphide" (1972). Open Access Dissertations. Paper 690. https://digitalcommons.uri.edu/oa_diss/690 This Dissertation is brought to you for free and open access by DigitalCommons@URI. It has been accepted for inclusion in Open Access Dissertations by an authorized administrator of DigitalCommons@URI. For more information, please contact [email protected]. T-P 7'i7 3. S ])5 Aisc°' .:. 1 SYNTHESIS AND CHARACTERIZATION OF DIAMOND AND BORON PHOSPHIDE / BY K. P. ANANTHANARAYANAN A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY IN CHEMICAL ENGINEERING UNIVERSITY OF RHODE ISLAND 1972 DOCTOR OF PHILOSOPHY THESIS OF K. P. ANANTHANARAYANAN Approved: Thesis Committee: Dean of the Graduate School UNIVERSITY OF RHODE ISLAND 1972 ABSTRACT Semiconducting diamond has been synthesized from carbon-metal melts in a 600 ton tetrahedral anvil press at about 60 kbar and 1400°c. The experimental set up, pressure and temperature calibra- tions, and the growth region in the pressure-temperature regime are indicated. Micrographs of synthesized crystals are shown. The semiconducting properties of diamond, doped with boron, aluminum and titanium have been interpreted using the log R versus l/T curves. In boron-doped diamond ''high concentration" type im- purity conduction occurs and the activation energies vary from 0.15 eV to 0.30 eV.
    [Show full text]
  • Ultrahigh Thermal Conductivity in Isotope-Enriched Cubic Boron Nitride
    Ultrahigh thermal conductivity in isotope-enriched cubic boron nitride The MIT Faculty has made this article openly available. Please share how this access benefits you. Your story matters. Citation Chen, Ke et al. "Ultrahigh thermal conductivity in isotope-enriched cubic boron nitride." Science 367, 6477 (January 2020): 555-559 © 2020 The Authors As Published http://dx.doi.org/10.1126/science.aaz6149 Publisher American Association for the Advancement of Science (AAAS) Version Author's final manuscript Citable link https://hdl.handle.net/1721.1/127819 Terms of Use Creative Commons Attribution-Noncommercial-Share Alike Detailed Terms http://creativecommons.org/licenses/by-nc-sa/4.0/ Ultrahigh thermal conductivity in isotope-enriched cubic boron nitride Ke Chen1*, Bai Song1*†‡,, Navaneetha K. Ravichandran2*, Qiye Zheng3§, Xi Chen4#, Hwijong Lee4, Haoran Sun5, Sheng Li6, Geethal Amila Gamage5, Fei Tian5, Zhiwei Ding1, Qichen Song1, Akash Rai3, Hanlin Wu6, Pawan Koirala6, Aaron J. Schmidt1, Kenji Watanabe7, Bing Lv6, Zhifeng Ren5, Li Shi4,8, David G. Cahill3, Takashi Taniguchi7, David Broido2†, and Gang Chen1† 1Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA. 2Department of Physics, Boston College, Chestnut Hill, MA 02467, USA. 3Department of Materials Science and Engineering and Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA. 4Materials Science and Engineering Program, Texas Materials Institute, The University of Texas at Austin, Austin, TX 78712, USA 5Department of Physics and Texas Center for Superconductivity, University of Houston, Houston, TX 77204, USA. 6Department of Physics, The University of Texas at Dallas, Richardson, TX 75080, USA. 7National Institute for Materials Science, Namiki 1-1, Tsukuba, Ibaraki 305-0044, Japan.
    [Show full text]