DOCSLIB.ORG

Amorphous Hydrogenated Boron Carbide for Solid-State

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Amorphous Hydrogenated Boron Carbide for Solid-State AMORPHOUS HYDROGENATED BORON CARBIDE FOR SOLID-STATE DIRECT-CONVERSION THERMAL NEUTRON DETECTION A DISSERTATION IN Physics and Chemistry Presented to the Faculty of the University of Missouri-Kansas City in partial fulfillment of the requirements for the degree DOCTOR OF PHILOSOPHY by GYANENDRA BHATTARAI B.Sc., Tribhuvan University, 1998 M.Sc., Tribhuvan University, 2007 M.S., University of Missouri-Kansas City, 2015 Kansas City, Missouri 2021 © 2021 GYANENDRA BHATTARAI ALL RIGHTS RESERVED AMORPHOUS HYDROGENATED BORON CARBIDE FOR SOLID-STATE DIRECT-CONVERSION THERMAL NEUTRON DETECTION Gyanendra Bhattarai, Candidate for the Doctor of Philosophy Degree University of Missouri-Kansas City, 2021 ABSTRACT Amorphous hydrogenated boron carbide (a-BC:H) is one of a very limited number of neutron-sensitive materials. It has been studied over the last three decades for solid-state thermal neutron detection due to its high resistivity, moderate bandgap, high neutron absorption cross-section, and high stability under harsh physical and chemical environment. However, its success has been hindered by its poor and/or not well understood charge transport properties as well as fabrication challenges. This study focuses on obtaining thick and stable a-BC:H films using plasma-enhanced chemical vapor deposition (PECVD) and optimizing their charge transport properties for potential application in solid-state direct-conversion thermal neutron detection. We have investigated the effect of single-carrier transport and low charge carrier mobility, which are expected in a-BC:H films, on detection efficiency and spectral performance of a thin-film B4C detector using numerical Monte Carlo calculations. Experimentally, we have used space-charge-limited current (SCLC) analysis to extract iii the charge carrier mobility in a-BC:H thin films. To better describe the extracted charge carrier mobility, we have presented an extension of SCLC theory to include negative field-dependence in mobility as well as a theory to check self-consistency of the extracted mobility. Toward obtaining stable thick films and optimizing the charge transport metrics, we have deposited multiple series’ of a-BC:H thin films using an ortho-carborane precursor with varying PECVD process parameters, including substrate temperature, RF power, process pressure, carrier gas flow rate, and partial precursor flow. Films grown using higher substrate temperature and higher RF power demonstrated higher charge carrier mobility. Partial precursor flow was found to correlate significantly with film growth rate and film properties. The precursor flow rate was found to be very sensitive to the precursor bubbler temperature, which allowed us to fine-tune the precursor flow and produce films with predictable growth rate and film properties. With optimized growth conditions, we demonstrated a 3 μm thick and stable film deposited on copper foil exhibiting a carrier mobility value of 8×10–6 cm2⋅V–1⋅s–1 and a resistivity value of ∼1012 Ω⋅cm. With this film thickness and carrier mobility, our Monte Carlo calculations suggested that a neutron detector using an integration time of ≥5 μs can detect neutrons for a carrier lifetime >10 μs, and the intrinsic detection efficiency saturates to ∼10% for a carrier lifetime ≥100 μs. iv APPROVAL PAGE The faculty listed below, appointed by the Dean of the College of Arts and Sciences have examined a dissertation titled “Amorphous Hydrogenated Boron Carbide for Solid-State Direct-Conversion Thermal Neutron Detection,” presented by Gyanendra Bhattarai, candidate for the Doctor of Philosophy degree, and certify that in their opinion it is worthy of acceptance. Supervisory Committee Anthony N. Caruso, Ph.D., Committee Chair Department of Physics and Astronomy Michelle M. Paquette, Ph.D., Research Advisor Department of Physics and Astronomy J. David Van Horn, Ph.D. Department of Chemistry Paul M. Rulis, Ph.D. Department of Physics and Astronomy Nathan A. Oyler, Ph.D. Department of Chemistry v TABLE OF CONTENTS ABSTRACT .................................................................................................................. iii LIST OF ILLUSTRATIONS ....................................................................................... xii LIST OF TABLES ................................................................................................... xxvii ACKNOWLEDGEMENTS ..................................................................................... xxxii CHAPTER 1 INTRODUCTION .................................................................................... 1 1.1. Motivation and Objectives ............................................................................. 4 1.1.1. Applications of Neutrons and Neutron Detectors .............................. 4 1.1.2. Need for Helium-3 Alternatives ........................................................ 6 1.1.3. Boron-10 Compounds for Direct-Conversion Semiconductor Neutron Detection ...................................................................................................... 9 1.1.4. Amorphous Boron Carbide Thermal Neutron Detectors ................. 10 1.2. Fundamentals of Neutron Detection ............................................................ 12 1.2.1. Interaction of Neutrons with Matter ................................................ 12 Neutron Scattering ..................................................................................... 14 Neutron Absorption ................................................................................... 18 1.2.2. Neutron Detection ............................................................................ 20 1.2.3. Solid-State (Semiconductor) Neutron Detectors ............................. 22 1.3. Amorphous Hydrogenated Boron Carbide (a-BC:H) for Direct-Conversion Thermal Neutron Detection: A Brief History ..................................................... 27 vi 1.4. Scope of Dissertation ................................................................................... 31 CHAPTER 2 DEVICE FABRICATION AND CHARACTERIZATION: THEORY AND EXPERIMENTS ................................................................................................. 33 2.1. Device Fabrication ....................................................................................... 33 2.1.1. PECVD Chamber ............................................................................. 33 2.1.2. Substrate Temperature Calibration .................................................. 38 2.1.3. Precursor Bubbler ............................................................................ 40 2.1.4. Substrate Preparation ....................................................................... 42 2.1.5. Film Growth..................................................................................... 44 2.1.6. Electrical Contact Deposition .......................................................... 47 2.1.7. Device Wiring .................................................................................. 49 2.2. Basic Characterization.................................................................................. 52 2.2.1. Spectroscopic Ellipsometry ............................................................. 52 2.2.2. UV-Visible Reflection and Transmission Spectroscopy ................. 55 2.2.3. Film Stress ....................................................................................... 59 2.3. Charge Transport Characterization .............................................................. 62 2.3.1. Dielectric Constant .......................................................................... 62 2.3.2. Steady-State Current–Voltage Measurements ................................. 64 2.3.3. Transient Photoconductivity ............................................................ 80 vii CHAPTER 3 SINGLE-CARRIER CHARGE COLLECTION IN THIN DIRECT- CONVERSION SEMICONDUCTOR NEUTRON DETECTOR: A NUMERICAL SIMULATION .............................................................................................................. 88 3.1. Introduction .................................................................................................. 88 3.2. Interaction of Thermal Neutrons with B4C .................................................. 93 3.3. Theory: Direct-Conversion Neutron Detection ............................................ 96 3.4. Simulation Setup ........................................................................................ 101 3.4.1. Detector Geometry, and Contacts .................................................. 101 3.4.2. Energy Deposition by Primary Reaction Products ........................ 102 3.4.3. Charge Carrier Excitation and Collection (Signal Generation) ..... 103 3.4.4. Simulation Process......................................................................... 106 3.5. Results and Discussion ............................................................................... 108 3.5.1. Total Energy Deposition: The Case of 100% Charge Collection of Both Types of Charge Carriers ................................................................ 108 3.5.2. Charge Collection Efficiency: Effect of Charge Transport Properties and Device Thickness .............................................................................. 111 3.5.3. Detection Efficiency: Effect of Charge Transport Properties and Device Thickness ..................................................................................... 116 3.5.4. Pulse Height Spectra: Effect of Charge Transport
Load more

Recommended publications
  • 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.
    [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]
  • 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]
  • Flexible Thermal Interface Based on Self-Assembled Boron Arsenide for High-Performance Thermal Management
    UCLA UCLA Previously Published Works Title Flexible thermal interface based on self-assembled boron arsenide for high-performance thermal management. Permalink https://escholarship.org/uc/item/4b77z423 Journal Nature communications, 12(1) ISSN 2041-1723 Authors Cui, Ying Qin, Zihao Wu, Huan et al. Publication Date 2021-02-24 DOI 10.1038/s41467-021-21531-7 Peer reviewed eScholarship.org Powered by the California Digital Library University of California ARTICLE https://doi.org/10.1038/s41467-021-21531-7 OPEN Flexible thermal interface based on self-assembled boron arsenide for high-performance thermal management ✉ Ying Cui1, Zihao Qin1, Huan Wu1, Man Li1 & Yongjie Hu 1 Thermal management is the most critical technology challenge for modern electronics. Recent key materials innovation focuses on developing advanced thermal interface of elec- 1234567890():,; tronic packaging for achieving efficient heat dissipation. Here, for the first time we report a record-high performance thermal interface beyond the current state of the art, based on self- assembled manufacturing of cubic boron arsenide (s-BAs). The s-BAs exhibits highly desirable characteristics of high thermal conductivity up to 21 W/m·K and excellent elastic compliance similar to that of soft biological tissues down to 100 kPa through the rational design of BAs microcrystals in polymer composite. In addition, the s-BAs demonstrates high flexibility and preserves the high conductivity over at least 500 bending cycles, opening up new application opportunities for flexible thermal cooling. Moreover, we demonstrated device integration with power LEDs and measured a superior cooling performance of s-BAs beyond the current state of the art, by up to 45 °C reduction in the hot spot temperature.
    [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]
  • Thermoelectric Transports in Pristine and Functionalized Boron Phosphide Monolayers Min‑Shan Li1,3, Dong‑Chuan Mo2,3 & Shu‑Shen Lyu2,3*
    www.nature.com/scientificreports OPEN Thermoelectric transports in pristine and functionalized boron phosphide monolayers Min‑Shan Li1,3, Dong‑Chuan Mo2,3 & Shu‑Shen Lyu2,3* Recently, a new monolayer Group III–V material, two‑dimensional boron phosphide (BP), has shown great potential for energy storage and energy conversion applications. We study the thermoelectric properties of BP monolayer as well as the efect of functionalization by frst‑principles calculation and Boltzmann transport theory. Combined with a moderate bandgap of 0.90 eV and ultra‑high carrier mobility, a large ZT value of 0.255 at 300 K is predicted for two‑dimensional BP. While the drastically reduced thermal conductivity in hydrogenated and fuorinated BP is favored for thermoelectric conversion, the decreased carrier mobility has limited the improvement of thermoelectric fgure of merit. Termoelectric material, which can directly convert waste heat into electricity, provides a promising solution for global issues like energy crisis1–4. Te thermoelectric performance of a material can be characterized by a dimensionless fgure of merit: S2σT ZT = , (1) kel + kla where S is the Seebeck coefcient, σ is the electronic conductivity, kel and kla are the thermal conductivities con- tributed by electrons and phonons, respectively. To obtain high thermoelectric performance, a material generally needs to have high electrical conductivity σ, high Seebeck coefcient S and low thermal conductivity k at the same time5. While the inter-coupling of the electronic parameters has made the optimization of thermoelectric performance a great challenge, early studies suggest that lowering the dimension of materials appears to be an efective approach6–9.
    [Show full text]
  • Advanced Crystal Growth Techniques with Iii-V Boron Compound
    ADVANCED CRYSTAL GROWTH TECHNIQUES WITH III-V BORON COMPOUND SEMICONDUCTORS by CLINTON E. WHITELEY B.S., Benedictine Collage, 2005 M.S., Kansas State University, 2008 AN ABSTRACT OF A DISSERTATION submitted in partial fulfillment of the requirements for the degree DOCTOR OF PHILOSOPHY Department of Chemical Engineering College of Engineering KANSAS STATE UNIVERSITY Manhattan, Kansas 2011 ABSTRACT Semiconducting icosahedral boron arsenide, B12As2, is an excellent candidate for neutron detectors and radioisotope batteries, for which high quality single crystals are required. Thus, the present study was undertaken to grow B12As2 crystals by precipitation from metal solutions (nickel) saturated with elemental boron and arsenic in a sealed quartz ampoule. B12As2 crystals of 8-10 mm were produced when a homogeneous mixture of the three elements was held at 1150 °C for 48-72 hours and slowly cooled (3°C/hr). The crystals varied in color and transparency from black and opaque to clear and transparent. X-ray topography (XRT), Raman spectroscopy, and defect selective etching confirmed that the crystals had the expected rhombohedral structure and a low density of defects (5x107 cm-2). The concentrations of residual impurities (nickel, carbon, etc) were found to be relatively high (1019 cm-3 for carbon) as measured by secondary ion mass spectrometry (SIMS) and elemental analysis by energy dispersive x-ray spectroscopy (EDS). The boron arsenide crystals were found to have favorable electrical properties (µ = 24.5 cm2 / Vs), but no interaction between a prototype detector and an alpha particle bombardment was observed. Thus, the flux growth method is viable for growing large B12As2 crystals, but the impurity concentrations remain a problem.
    [Show full text]
  • Boron Isotope Effect on the Thermal Conductivity of Boron Arsenide Single Crystals
    Boron isotope effect on the thermal conductivity of boron arsenide single crystals Haoran Sun1, Ke Chen2, Geethal Amila Gamage1, Hamidreza Ziyaee3, Fei Wang1, Yu Wang1,4, Viktor G. Hadjiev3, Fei Tian1†, Gang Chen2, and Zhifeng Ren1† 1 Department of Physics and Texas Center for Superconductivity (TcSUH), University of Houston, Houston, Texas 77204, USA 2 Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA 3 Department of Mechanical Engineering and Texas Center for Superconductivity (TcSUH), University of Houston, Houston, Texas 77204, USA 4 Institute of Advanced Materials, Hubei Normal University, Huangshi, Hubei 435002, China †To whom correspondence should be addressed, email: [email protected], [email protected] Abstract Boron arsenide (BAs) with a zinc blende structure has recently been discovered to exhibit unusual and ultrahigh thermal conductivity (k), providing a new outlook for research on BAs and other high thermal conductivity materials. Technology for BAs crystal growth has been continuously improving, however, the influence of boron isotopes, pure or mixed, on the thermal conductivity in BAs is still not completely clear. Here we report detailed studies on the growth of single crystals of BAs with different isotopic ratios and demonstrate that the k of isotopically pure BAs is at least 10% higher than that of BAs grown from natural B. Raman spectroscopy characterization shows differences in scattering among various BAs samples. The presented results will be helpful in guiding further studies on the 1 influence of isotopes on optimizing k in BAs. 2 Introduction The heat produced in high power density electronic devices imposes a major limitation on the performance of these devices.
    [Show full text]
  • Cubic Boron Phosphide Epitaxy on Zirconium Diboride Balabalaji Padavala, H
    Cubic boron phosphide epitaxy on zirconium diboride Balabalaji Padavala, H. Al Atabi, Lina Tengdelius, Jun Lu, Hans Högberg and J. H. Edgar The self-archived postprint version of this journal article is available at Linköping University Institutional Repository (DiVA): http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-144241 N.B.: When citing this work, cite the original publication. Padavala, B., Al Atabi, H., Tengdelius, L., Lu, J., Högberg, H., Edgar, J. H., (2018), Cubic boron phosphide epitaxy on zirconium diboride, Journal of Crystal Growth, 483, 115-120. https://doi.org/10.1016/j.jcrysgro.2017.11.014 Original publication available at: https://doi.org/10.1016/j.jcrysgro.2017.11.014 Copyright: Elsevier http://www.elsevier.com/ Cubic Boron Phosphide Epitaxy on Zirconium Diboride Balabalaji Padavala1, H. Al Atabi1, Lina Tengdelius2, Jun Lu2, Hans Högberg2 and J.H. Edgar1 Kansas State University, Department of Chemical Engineering, Durland Hall, Manhattan, KS 66506, USA Thin Film Physics Division, Department of Physics, Chemistry, and Biology (IFM), Linköping University, SE-581 83 Linköping, Sweden Abstract Cubic boron phosphide (BP) is one of the least studied III-V compound semiconductors, in part because it is difficult to prepare in high quality form. In this study, zirconium diboride (ZrB2) was studied as a potential substrate for BP epitaxial layers, because of its advantages of a low lattice constant mismatch and high thermal stability. Two types of substrates were considered: ZrB2(0001) epitaxial films on 4H- SiC(0001) and bulk ZrB2(0001) single crystals. The optimal temperature for epitaxy on these substrates was 1100 °C; higher and lower temperatures resulted in polycrystalline films.
    [Show full text]
  • 1.2 Boron Arsenide: Structure, Properties and Applications
    THE PENNSYLVANIA STATE UNIVERSITY SCHREYER HONORS COLLEGE DEPARTMENT OF MATERIALS SCIENCE AND ENGINEERING INVESTIGATION OF METAL THIN-FILMS ON BORON ARSENIDE AND HEXAGONAL BORON NITRIDE RAJEH SALAH R. ALSAADI SPRING 2020 A thesis submitted in partial fulfillment of the requirements for a baccalaureate degree in Materials Science and Engineering with honors in Materials Science and Engineering Reviewed and approved* by the following: Suzanne E. Mohney Professor of Materials Science and Engineering and Electrical Engineering Thesis Supervisor Robert A. Kimel Associate Teaching Professor of Materials Science and Engineering Honors Adviser * Electronic approvals are on file. i ABSTRACT Boron arsenide (BAs) and hexagonal boron nitride (h-BN) are of great interest for the development of next-generation electronic and optoelectronic devices due to their potential for superior performance for heat management and as insulating two-dimensional layered materials, respectively. Studies of metal electrical contacts to BAs, or heterojunctions involving metals and h-BN, are scarce in the literature. A device with BAs as an active semiconducting layer would require electrical contacts, so reactivity at metal/BAs interfaces were assessed based on condensed phase equilibria for metal-B-As systems. A MATLAB program was utilized to calculate the ternary phase diagrams for BAs with Pt, Mo, Cr, Ti, Au and Ag at room temperature. Platinum, Mo, Cr and Ti demonstrate are predicted to have exhibit a thermodynamic drive to react with BAs, while Au and Ag are in thermodynamic equilibrium with BAs. Assessment of stability of thin metal films on h-BN involved collection of condensed phase equilibria for metal-B-N systems from the literature, which showed that the early transition metals Cr, V, Ti, Zr, and Al have a thermodynamic driving force to react, while later transition metals Fe, Co, Ni, Mn, Au, Ag, Cu and Cd are expected to be stable on h-BN.
    [Show full text]
  • Guideline Ver6.2 Se Ria L No. CAS RN® Substance Group 1 Substance
    Guideline Ver6.2 Rank CAS RN® Substance Group 1 Substance Group 2 Substance Name 1=Prohibited No. Serial 2=Reduction 1 124-73-2 ozone depleting substances(Halons) Ethane, 1,2-dibromo-1,1,2,2-tetrafluoro- 1 2 25497-30-7 ozone depleting substances(Halons) Dibromotetrafluoroethane 1 3 27336-23-8 ozone depleting substances(Halons) Dibromotetrafluoroethane,compressed 1 4 353-59-3 ozone depleting substances(Halons) Methane, bromochlorodifluoro- 1 5 354-56-3 ozone depleting substances(Halons) Ethane, pentachlorofluoro- 1 6 75-61-6 ozone depleting substances(Halons) Methane, dibromodifluoro- 1 7 75-63-8 ozone depleting substances(Halons) Methane, bromotrifluoro- 1 8 110003-27-5 ozone depleting substances(HBFCs) 1,3-dibromo-1,1,2-trifluoropropane 1 9 111483-20-6 ozone depleting substances(HBFCs) 1-bromo-2,3-difluoropropane 1 10 124-72-1 ozone depleting substances(HBFCs) 2-bromo-1,1,1,2-tetrafluoroethane 1 11 148875-95-0 ozone depleting substances(HBFCs) C3H3FBr4 1 12 148875-98-3 ozone depleting substances(HBFCs) C3H2F2Br4 1 13 1511-62-2 ozone depleting substances(HBFCs) Methane, bromodifluoro- 1 14 172912-75-3 ozone depleting substances(HBFCs) HBFC-131 B3 Tribromofluoroethane 1 15 1800-81-3 ozone depleting substances(HBFCs) 1-bromo-1,2-difluoroethane 1 16 1868-53-7 ozone depleting substances(HBFCs) Dibromofluoromethane 1 17 1871-72-3 ozone depleting substances(HBFCs) FLUOROBROMOPROPANE 1 18 2252-78-0 ozone depleting substances(HBFCs) 1-Bromo-1,1,2,3,3,3-hexafluoropropane 1 19 2252-79-1 ozone depleting substances(HBFCs) 2-bromo-1,1,1,3,3,3-hexafluoropropane
    [Show full text]
  • Abstract Development of Boron-Arsenide-Based
    ABSTRACT DEVELOPMENT OF BORON-ARSENIDE-BASED COMPOSITES AS THERMAL INTERFACE MATERIALS FOR HIGH POWER GENERATING ELECTRONICS MODULES Vignesh Varadaraju, MS Department of Mechanical Engineering Northern Illinois University, 2017 Dr. Pradip Majumdar, Director Thermal management is one of the most critical issues in electronics due to increasing power densities. This problem is getting even worse for small and sophisticated devices due to air gaps present between the heat source and heat sink; air gaps are thermal barriers to the heat dissipation path. Thermal interface materials (TIM) are used to reduce the air gaps; TIM placed in between heat source and heat sink significantly increases the heat transfer capability of the system. The ability to work at large temperature cycling results in reduction of thermos- mechanical reliability for the traditional TIMs. A high-thermal-performance, cost-effective and reliable TIM would be needed to dissipate the generated heat, which could enable significant reductions in weight, volume and cost of the thermal management system. The objective of this research is to design advanced TIM by finding the composition of boron arsenide as filler in polymer-nanostructured material which can outperform traditional TIMs when it is used in high-heat fluxes applications including space and aero-space applications. A three-dimensional computational analysis model is developed to evaluate boron- arsenide-based TIM in terms of spreading heat and reduction junction temperature using an insulated gate bipolar transistor (IGBT) power module in a forced-air convective environment. NORTHERN ILLINOIS UNIVERSITY DEKALB, ILLINOIS AUGUST 2017 DEVELOPMENT OF BORON-ARSENIDE-BASED COMPOSITES AS THERMAL INTERFACE MATERIALS FOR HIGH POWER GENERATING ELECTRONICS MODULES BY VIGNESH VARADARAJU ©2017 Vignesh Varadaraju A THESIS SUBMITTED TO THE GRADUATE SCHOOL IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE MASTER OF SCIENCE DEPARTMENT OF MECHANICAL ENGINEERING Thesis Director: Dr.
    [Show full text]