DOCSLIB.ORG

SYNTHESIS and NANOENGINEERING of GALLIUM PHOSPHIDE NANOSTRUCTURES for PHOTOELECTROCHEMICAL SOLAR ENERGY CONVERSION by Wen Wen A

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
SYNTHESIS and NANOENGINEERING of GALLIUM PHOSPHIDE NANOSTRUCTURES for PHOTOELECTROCHEMICAL SOLAR ENERGY CONVERSION by Wen Wen A SYNTHESIS AND NANOENGINEERING OF GALLIUM PHOSPHIDE NANOSTRUCTURES FOR PHOTOELECTROCHEMICAL SOLAR ENERGY CONVERSION by Wen Wen A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy (Chemistry) in The University of Michigan 2014 Doctoral Committee: Assistant Professor Stephen Maldonado, Chair Assistant Professor Bart Bartlett Associate Professor Peicheng Ku Professor Adam Matzger © Wen Wen All Rights Reserved 2014 DEDICATION For my parents, my husband and my daughter. ii ACKNOWLEDGMENT First, I would like to thank my advisor, Professor Stephen Maldonado. Thank you very much for your patient guidance during my last five years. I want to thank you for taking time for one-to-one weekly meeting with me for 5 years and preparing me for each important stage in graduate school (seminar, candidacy, data meeting and defense). I also would like to thank my committee member, Professor Adam Matzger, Professor Bart Bartlett and Professor Peicheng Ku. Dr. Matzger, I started my graduate school by rotating in your group. It is an invaluable experience. And I also want to thank you so much for letting using instruments in your lab. Dr. Bartlett, I took Inorganic Chemistry with you, I learned a lot from your class and it is very helpful in my PhD. research, thank you. Dr. Ku, thank you very much for your feedback and advice for my research during our meeting. Looking back to my past five years in graduate school, I think I could not feel any luckier to know my labmates. Thank you very much for your help and support. Sean Collin, for taking me to numerous SEM and TEM sections and you are always very patient to answer my question. Azhar Carim, for helping me with characterization of my samples and showing me a lot of tricks. Dr. Michelle Chitamber, for helping me out with the spectral response, even you left, your promote reply for my questions is very helpful. Dr. Jeremy Feldblyum, for your friendship and you are always there to encourage me. Sabrina Peczonczyk and Junsi Gu, my peers for five years, we went through each milestone of Ph.D life together and thank you so much for your support. Eli Fahrenkrug, for being a nice cubemate and your helpful advices in research and life. Besty Brown, for always being very sweet, no matter your candies or your kind comforts. Luyao Ma, Sudarat Lee and Tim Zhang, for taking lab duties and your support. This dissertation could not be done with the help from the department staffs. I would greatly thank Roy Wentz from glass shop, you are always there whenever I need to try new setups and offer me countless good ideas to make them happen. Stephen iii Donajkowski from machine shop, for always helping me fixing instruments promptly. Dr. Haiping Sun and Dr. Kai Sun from EMAL, for your generous help in solving technical problems. I would like to take this opportunity to thank my previous advisors, Professor Ranko Richert from Arizona State and Professor Kai Wu from Peking University, for your patient guidance and great support. Last but not least, I would like to thank my family. My parents, for giving me a family surrounded with love and raising me up to who I am with endless love and support. My husband Chen Ling, the love of my life. You are always there supporting me through all the frustrations and challenges I met. I could not imagine I can get to the point of what I am now without you. I am looking forward to share the journal of the rest of my life with you. iv TABLE OF CONTENTS DEDICATION................................................................................................................... ii ACKNOWLEDGMENT ................................................................................................. iii LIST OF FIGURES ....................................................................................................... viii LIST OF TABLES ......................................................................................................... xiv ABSTRACT ..................................................................................................................... xv CHAPTER I Introduction ................................................................................................ 1 I.1 Importance of Solar Energy ...................................................................................... 1 I.2 Solar Energy Conversion .......................................................................................... 1 I.2.1 Photosynthetic Energy Storage ........................................................................... 2 I.2.2 Photovoltaic Energy Conversion ........................................................................ 2 I.2.3 Photoelectrochemical (PEC) System .................................................................. 6 I.3 Gallium Phosphide Nanowires for PEC Application .............................................. 19 I.4 Content Description ................................................................................................ 20 I.5 References ............................................................................................................... 23 CHAPTER II Photoelectrochemical Behavior of n-type Gallium Phosphide Nanowires as Photoanodes ............................................................................................. 28 II.1 Introduction ............................................................................................................ 28 II.2 Methods ................................................................................................................. 29 II.2.1 Preparation of GaP Nanowires ........................................................................ 29 II.2.2 SEM/TEM Characterization of GaP Nanowires .............................................. 29 II.2.3 Diffuse Reflectance Measurement ................................................................... 29 II.2.4 Photoelectrochemistry ..................................................................................... 32 II.3 Results .................................................................................................................... 33 II.3.1 Morphology of GaP Nanowries ....................................................................... 33 II.3.2 Photoelectrochemical Response of as-Prepared Nanowire Films ................... 33 v II.3.3 Diffusive Reflectance Measurement of GaP Nanowire Films ........................ 38 II.3.4 Spectral Response of Nanowires in Different Electrolytes ............................. 38 II.3.5 Effect of Catalyst Residue in the Overall Quantum Yield Performance ......... 40 II.4 Discussion .............................................................................................................. 42 II.5 Conclusions ............................................................................................................ 46 II.6 References .............................................................................................................. 46 CHAPTER III Structural and Photoelectrochemical Properties of Gallium Phosphide Nanowires Annealed in NH3 ........................................................................ 49 III.1 Introduction .......................................................................................................... 49 III.2 Methods ................................................................................................................ 51 III.2.1 GaP Nanowire Film Preparation .................................................................... 51 III.2.2 Materials Characterization ............................................................................. 51 III.2.3 Photoelectrochemical Measurements ............................................................. 55 III.3 Results .................................................................................................................. 55 III.3.1 X-ray Diffraction ............................................................................................ 55 III.3.2 Diffuse Reflectance ........................................................................................ 57 III.3.3 Raman Spectroscopy ...................................................................................... 59 III.3.4 Transmission Electron Microscopy ................................................................ 65 III.3.5 X-ray Photoelectron Spectroscopy ................................................................. 69 III.3.6 Long Wavelength Photoelectrochemical Conversion .................................... 72 III.4 Discussion ............................................................................................................ 74 III.5 Conclusions .......................................................................................................... 77 III.6 References ............................................................................................................ 78 CHAPTER IV Zinc Doping of Gallium Phosphide Nanowire Films ......................... 82 IV.1 Introduction .......................................................................................................... 82 IV.2 Methods ................................................................................................................ 83 IV.2.1 Zinc Doping Methods .................................................................................... 83 IV.2.2 Photoelectrochemical Measurements ............................................................
Load more

Recommended publications
  • Environmental Properties of Chemicals Volume 2
    1 t ENVIRONMENTAL 1 PROTECTION Esa Nikunen . Riitta Leinonen Birgit Kemiläinen • Arto Kultamaa Environmental properties of chemicals Volume 2 1 O O O O O O O O OO O OOOOOO Ol OIOOO FINNISH ENVIRONMENT INSTITUTE • EDITA Esa Nikunen e Riitta Leinonen Birgit Kemiläinen • Arto Kultamaa Environmental properties of chemicals Volume 2 HELSINKI 1000 OlO 00000001 00000000000000000 Th/s is a second revfsed version of Environmental Properties of Chemica/s, published by VAPK-Pub/ishing and Ministry of Environment, Environmental Protection Department as Research Report 91, 1990. The pubiication is also available as a CD ROM version: EnviChem 2.0, a PC database runniny under Windows operating systems. ISBN 951-7-2967-2 (publisher) ISBN 952-7 1-0670-0 (co-publisher) ISSN 1238-8602 Layout: Pikseri Julkaisupalvelut Cover illustration: Jussi Hirvi Edita Ltd. Helsinki 2000 Environmental properties of chemicals Volume 2 _____ _____________________________________________________ Contents . VOLUME ONE 1 Contents of the report 2 Environmental properties of chemicals 3 Abbreviations and explanations 7 3.1 Ways of exposure 7 3.2 Exposed species 7 3.3 Fffects________________________________ 7 3.4 Length of exposure 7 3.5 Odour thresholds 8 3.6 Toxicity endpoints 9 3.7 Other abbreviations 9 4 Listofexposedspecies 10 4.1 Mammais 10 4.2 Plants 13 4.3 Birds 14 4.4 Insects 17 4.5 Fishes 1$ 4.6 Mollusca 22 4.7 Crustaceans 23 4.8 Algae 24 4.9 Others 25 5 References 27 Index 1 List of chemicals in alphabetical order - 169 Index II List of chemicals in CAS-number order
    [Show full text]
  • Efficacy of 3 In-Burrow Treatments to Control Black-Tailed Prairie Dogs
    EFFICACY OF 3 JN-BURROW TREATMENTS TO CONTROL BLACK-TAJLED PRAIRIE DOGS CHARLES D. LEE, Department of Animal Science, Kansas State University Research and Extension, Manhattan, KS, USA JEFF LEFLORE , East Cheyenne County Pest Control, Cheyenne Wells , CO, USA Abstract: Management of prairie dog ( Cynomys ludovicianus) movement by colony expansion or dispersal may involve the use of toxicants to reduce local populations. Hazards associated with the use of toxicants cause concern for non-target species. Applying the bait in-burrow should reduce the primary exposure of the toxicants to non-target wildlife. Some literature suggests prairie dogs will not consume bait when applied in the burrow. In this trial we compared efficacy of Rozol ® (chlorophacinone), Kaput-D Prairie Dog Bait ® (diphacinone), 2% zinc phosphide oats applied in-burrow and 2% zinc phosphide oats applied on the surface. Results are reported as change in prairie dog activity. Key words: chlorophacinone , control, Cynomys ludovicianus, diphacinone, in-burrow, management , prairie dog, toxicant , zinc phosphide Proceedings of the I 2'h Wildlife Damage Management Conference (D.L. Nolte , W.M. Arjo, D.H. Stalman, Eds). 2007 INTRODUCTION This type of controversy has lead to scrutiny Control of black-tailed prame dogs of all types of control , especially the use of (Cynomys ludovicianus) is controversial on toxicants . Although there are numerous the Great Plains. Prairie dogs have been control techniques for prairie dogs, many controlled on rangeland for many years landowner s are dissatisfied with their largely with the use of toxicants applied consistency of efficacy and ease of use . above ground (Witmer and Fagerstone Most of the literature on black-tailed 2003).
    [Show full text]
  • Sound Management of Pesticides and Diagnosis and Treatment Of
    * Revision of the“IPCS - Multilevel Course on the Safe Use of Pesticides and on the Diagnosis and Treatment of Presticide Poisoning, 1994” © World Health Organization 2006 All rights reserved. The designations employed and the presentation of the material in this publication do not imply the expression of any opinion whatsoever on the part of the World Health Organization concerning the legal status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries. Dotted lines on maps represent approximate border lines for which there may not yet be full agreement. The mention of specific companies or of certain manufacturers’ products does not imply that they are endorsed or recommended by the World Health Organization in preference to others of a similar nature that are not mentioned. Errors and omissions excepted, the names of proprietary products are distinguished by initial capital letters. All reasonable precautions have been taken by the World Health Organization to verify the information contained in this publication. However, the published material is being distributed without warranty of any kind, either expressed or implied. The responsibility for the interpretation and use of the material lies with the reader. In no event shall the World Health Organization be liable for damages arising from its use. CONTENTS Preface Acknowledgement Part I. Overview 1. Introduction 1.1 Background 1.2 Objectives 2. Overview of the resource tool 2.1 Moduledescription 2.2 Training levels 2.3 Visual aids 2.4 Informationsources 3. Using the resource tool 3.1 Introduction 3.2 Training trainers 3.2.1 Organizational aspects 3.2.2 Coordinator’s preparation 3.2.3 Selection of participants 3.2.4 Before training trainers 3.2.5 Specimen module 3.3 Trainers 3.3.1 Trainer preparation 3.3.2 Selection of participants 3.3.3 Organizational aspects 3.3.4 Before a course 4.
    [Show full text]
  • Economic Implications of Using Zinc Phosphide to Replace Endrin in Apple Orchards
    University of Nebraska - Lincoln DigitalCommons@University of Nebraska - Lincoln Wildlife Damage Management, Internet Center Eastern Pine and Meadow Vole Symposia for March 1977 Economic Implications of Using Zinc Phosphide To Replace Endrin in Apple Orchards Walter L. Ferguson Economic Research Service Follow this and additional works at: https://digitalcommons.unl.edu/voles Part of the Environmental Health and Protection Commons Ferguson, Walter L., "Economic Implications of Using Zinc Phosphide To Replace Endrin in Apple Orchards" (1977). Eastern Pine and Meadow Vole Symposia. 116. https://digitalcommons.unl.edu/voles/116 This Article is brought to you for free and open access by the Wildlife Damage Management, Internet Center for at DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in Eastern Pine and Meadow Vole Symposia by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln. 33 Economic Implications of Using Zinc Phosphide To Replace Endrin in Apple Orchards 11 Walter L. Ferguson II Consideration is being given to suspend or restrict the use of endrin for controlling mice in orchards. If endrin were not available for this use, State extension and experiment station personnel in 6 Eastern States and 2 Western States estimated that apple production losses would increase from mice injury on 33,400 endrin-treated bearing acres, (12,500 acres in the Eastern States and 20,900 acres in the Western States). The 6 Eastern States include Georgia, Maryland, North Carolina, South Carolina, Virginia and West Virginia: the 2 Western States are Idaho and Washington. Estimates of production changes without endrin were made assuming zinc phosphide is the only feasible Federally registered chemical alternative to endrin.
    [Show full text]
  • RRAC Guidelines on Anticoagulant Rodenticide Resistance Management Editor: Rodenticide Resistance Action Committee (RRAC) of Croplife International Aim
    RRAC guidelines on Anticoagulant Rodenticide Resistance Management Editor: Rodenticide Resistance Action Committee (RRAC) of CropLife International Aim This document provides guidance to advisors, national authorities, professionals, practitioners and others on the nature of anticoagulant resistance in rodents, the identification of anticoagulant resistance, strategies for rodenticide application that will avoid the development of resistance and the management of resistance where it occurs. The Rodenticide Resistance Action Committee (RRAC) is a working group within the framework of CropLife International. Participating companies include: Bayer CropScience, BASF, LiphaTech S. A., PelGar, Rentokil Initial, Syngenta and Zapi. Senior technical specialists, with specific expertise in rodenticides, represent their companies on this committee. The RRAC is grateful to the following co-authors: Stefan Endepols, Alan Buckle, Charlie Eason, Hans-Joachim Pelz, Adrian Meyer, Philippe Berny, Kristof Baert and Colin Prescott. Photos provided by Stefan Endepols. Contents 1. Introduction ............................................................................................................................................................................................................. 2 2. Classification and history of rodenticide compounds ..............................................................................................3 3. Mode of action of anticoagulant rodenticides, resistance mechanisms, and resistance mutations ......................................................................................................6
    [Show full text]
  • Supporting Information For: Solution Phase Synthesis of Indium Gallium Phosphide Alloy Nanowires Nikolay Kornienko , Desiré D
    Supporting Information for: Solution Phase Synthesis of Indium Gallium Phosphide Alloy Nanowires Nikolay Kornienko1, Desiré D. Whitmore1, Yi Yu1, Stephen R. Leone1,2,4, Peidong Yang*1,3,5,6 1Department of Chemistry, 2Department of Physics and 3Department of Materials Science Engineering, University of California, Berkeley 94720, United States 4Chemical Sciences Division and 5Materials Sciences Division, Lawrence Berkeley National Lab, Berkeley CA 94720, United States 6Kavli Energy Nanosciences Institute, Berkeley, California 94720, United States * Correspondence to: [email protected] Table of Contents: Figure S1. TEM In/Ga growth seeds ............................................................................................................................. 2 Figure S2. TEM of InP and GaP NWs ............................................................................................................................. 2 Figure S3. Composition and diameter control ......................................................................................................... 3 Figure S4. XRD of InxGa1‐xP NWs .................................................................................................................................. 4 Figure S5. Electron diffraction of InxGa1‐xP NWs ................................................................................................... 5 Figure S6. Raman spectra of InP and GaP .................................................................................................................. 6
    [Show full text]
  • Arxiv:1010.1610V1 [Physics.Ins-Det] 8 Oct 2010 Ai Mouneyrac, David Emndtetm Osat O H Rpigadde- and Illumination
    Detrapping and retrapping of free carriers in nominally pure single crystal GaP, GaAs and 4H-SiC semiconductors under light illumination at cryogenic temperatures David Mouneyrac,1,2 John G. Hartnett,1 Jean-Michel Le Floch,1 Michael E. Tobar,1 Dominique Cros,2 Jerzy Krupka3∗ 1School of Physics, University of Western Australia 35 Stirling Hwy, Crawley 6009 WA Australia 2Xlim, UMR CNRS 6172, 123 av. Albert Thomas, 87060 Limoges Cedex - France 3Institute of Microelectronics and Optoelectronics Department of Electronics, Warsaw University of Technology, Warsaw, Poland (Dated: October 27, 2018) We report on extremely sensitive measurements of changes in the microwave properties of high purity non-intentionally-doped single-crystal semiconductor samples of gallium phosphide, gallium arsenide and 4H-silicon carbide when illuminated with light of different wavelengths at cryogenic temperatures. Whispering gallery modes were excited in the semiconductors whilst they were cooled on the coldfinger of a single-stage cryocooler and their frequencies and Q-factors measured under light and dark conditions. With these materials, the whispering gallery mode technique is able to resolve changes of a few parts per million in the permittivity and the microwave losses as compared with those measured in darkness. A phenomenological model is proposed to explain the observed changes, which result not from direct valence to conduction band transitions but from detrapping and retrapping of carriers from impurity/defect sites with ionization energies that lay in the semicon- ductor band gap. Detrapping and retrapping relaxation times have been evaluated from comparison with measured data. PACS numbers: 72.20.Jv 71.20.Nr 77.22.-d I.
    [Show full text]
  • Rodenticidal Effects of Zinc Phosphide and Strychnine of Nontarget Species
    University of Nebraska - Lincoln DigitalCommons@University of Nebraska - Lincoln Great Plains Wildlife Damage Control Workshop Wildlife Damage Management, Internet Center Proceedings for April 1987 Rodenticidal Effects of Zinc Phosphide and Strychnine of Nontarget Species Daniel W. Uresk Rocky Mountain Forest and Range Experiment Station, Rapid City, South Dakota Rudy M. King Rocky Mountain Forest and Range Experiment Station, Rapid City, South Dakota Anthony D. Apa South Dakota School of Mines and Technology Michele S. Deisch South Dakota School of Mines and Technology Raymond L. Linder South Dakota Cooperative Fish and Wildlife Research Unit, South Dakota State University - Brookings Follow this and additional works at: https://digitalcommons.unl.edu/gpwdcwp Part of the Environmental Health and Protection Commons Uresk, Daniel W.; King, Rudy M.; Apa, Anthony D.; Deisch, Michele S.; and Linder, Raymond L., "Rodenticidal Effects of Zinc Phosphide and Strychnine of Nontarget Species" (1987). Great Plains Wildlife Damage Control Workshop Proceedings. 102. https://digitalcommons.unl.edu/gpwdcwp/102 This Article is brought to you for free and open access by the Wildlife Damage Management, Internet Center for at DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in Great Plains Wildlife Damage Control Workshop Proceedings by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln. Rodenticidal Effects of Zinc Phosphide and Strychnine on Nontarget Species1 Daniel W. Uresk, Rudy M. King, Anthony D. Apa, Michele S. Deisch, and Raymond L. Linder Abstract.—When three rodenticide treatments—zinc phosphide (prebaited) and strychnine (both with and without prebait)—were evaluated, zinc phosphide was the most effec- tive in reducing active burrows of prairie dogs; but, it also resulted in a reduction in deer mouse densities.
    [Show full text]
  • (Mrls) for Phosphane and Phosphide Salts According to Article 12 of Regulation (EC) No 396/2005
    REASONED OPINION APPROVED: 25 November 2015 PUBLISHED: 04 December 2015 doi:10.2903/j.efsa.2015.4325 Review of the existing maximum residue levels (MRLs) for phosphane and phosphide salts according to Article 12 of Regulation (EC) No 396/2005 European Food Safety Authority (EFSA) Abstract According to Article 12 of Regulation (EC) No 396/2005, the European Food Safety Authority (EFSA) has reviewed the maximum residue levels (MRLs) currently established at European level for phosphane; this residue may result from the use of phosphane itself or from the use of certain phosphide salts. In order to assess the occurrence of phosphane residues in plants, processed commodities, rotational crops and livestock, EFSA considered the conclusions derived in the framework of Directive 91/414/EEC, the MRLs established by the Codex Alimentarius Commission as well as the European authorisations reported by Member States (incl. the supporting residues data). Based on the assessment of the available data, MRL proposals were derived and a consumer risk assessment was carried out. Although no apparent risk to consumers was identified, some information required by the regulatory framework was missing. Hence, the consumer risk assessment is considered indicative only and some MRL proposals derived by EFSA still require further consideration by risk managers. © European Food Safety Authority, 2015 Keywords: phosphane, phosphide, MRL review, Regulation (EC) No 396/2005, consumer risk assessment, fumigant Requestor: European Commission Question number: EFSA-Q-2009-00095; EFSA-Q-2009-00151; EFSA-Q-2009-00157; EFSA-Q-2009-00173; EFSA-Q-2012-00944 Correspondence: [email protected] www.efsa.europa.eu/efsajournal EFSA Journal 2015;13(12):4325 Review of the existing MRLs for phosphane and phosphide salts Acknowledgement: EFSA wishes to thank the rapporteur Member State Germany for the preparatory work on this scientific output.
    [Show full text]
  • Acute Oral Toxicity and Repellency of 933 Chemicals to House and Deer Mice
    U.S. Department of Agriculture U.S. Government Publication Animal and Plant Health Inspection Service Wildlife Services Archiv-of Arch. Environ. Contam. Toxicol. 14, 111-129 (1985) Environmental ontamination C ... ■ nd I oxicolagy © 1985 Springer-Verlag New York Inc. Acute Oral Toxicity and Repellency of 933 Chemicals to House and Deer Mice E. W. Schafer, Jr. and W. A. Bowles, Jr. U.S. Department of Interior - Fish and Wildlife Service, Denver Wildlife Research Center, Building 16 - Denver Federal Center, Denver, Colorado 80225 Abstract. Five individual bioassay repellency or deer mice and white (house) mice. Our purpose is toxicity variables were estimated or determined for to make available these generally unpublished test deer .mice (Peromyscus maniculatus) and house results so that they can be referenced or used by mice (Mus musculus) under laboratory conditions. the various public, private, and governmental ALD's (Approximate Lethal Doses) or LD50's of groups that may require this information. 230 chemicals to deer mice are presented, as are food reduction (FR) values (3-day feeding test as a 2.0% treatment rate) for white wheat seeds (Tri­ Methods ticum aestivum) for 696 chemicals and Douglas fir seeds (Pseudotsuga menziesii) for 81 chemicals. A The chemicals included in the tests were technical or analytical similar repellency evaluation (REP) using a 5-day grade pesticides and other commercially available or experi­ mental chemicals. They were purchased from various commer­ test with white wheat seeds at a 2.0% treatment rate cial sources or contributed by cooperating chemical companies. was conducted with house mice and the results for For presentation purposes, they have been arranged by Chemical 347 chemicals are presented.
    [Show full text]
  • Basic Light Emitting Diodes
    The following is for information purposes only and comes with no warranty. See http://www.bristolwatch.com/ Light Emitting Diodes Light Emitting Diodes are made from compound type semiconductor materials such as Gallium Arsenide (GaAs), Gallium Phosphide (GaP), Gallium Arsenide Phosphide (GaAsP), Silicon Carbide (SiC) or Gallium Indium Nitride (GaInN). The exact choice of the semiconductor material used will determine the overall wavelength of the photon light emissions and therefore the resulting color of the light emitted, as in the case of the visible light colored LEDs, (RED, AMBER, GREEN etc). Before a light emitting diode can "emit" any form of light it needs a current to flow through it, as it is a current dependent device. As the LED is to be connected in a forward bias condition across a power supply it should be Current Limited using a series resistor to protect it from excessive current flow. From the table above we can see that each LED has its own forward voltage drop across the PN junction and this parameter which is determined by the semiconductor material used is the forward voltage drop for a given amount of forward conduction current, typically for a forward current of 20mA. In most cases LEDs are operated from a low voltage DC supply, with a series resistor to limit the forward current to a suitable value from say 5mA for a simple LED indicator to 30mA or more where a high brightness light output is needed. Typical LED Characteristics Semiconductor Material Wavelength Color voltage at 20mA GaAs 850-940nm Infra-Red 1.2v GaAsP 630-660nm Red 1.8v GaAsP 605-620nm Amber 2.0v GaAsP:N 585-595nm Yellow 2.2v GaP 550-570nm Green 3.5v SiC 430-505nm Blue 3.6v GaInN 450nm White 4.0v 1 Multi-LEDs LEDs are available in a wide range of shapes, colors and various sizes with different light output intensities available, with the most common (and cheapest to produce) being the standard 5mm Red LED.
    [Show full text]
  • Nonlinear Properties of III-V Semiconductor Nanowaveguides
    Nonlinear Properties of III-V Semiconductor Nanowaveguides ELEONORA DE LUCA Doctoral Thesis in Physics School of Engineering Sciences KTH Royal Institute of Technology Stockholm, Sweden 2019 Akademisk avhandling som med tillstånd av Kungliga Tekniska högskolan fram- lägges till offentlig granskning för avläggande av teknologie doktorsexamen i fysik onsdag den 23 oktober 2019 klockan 10:00 i sal FA32, AlbaNova Universitetscent- rum, Kungliga Tekniska Högskolan, Roslagstullsbacken 21, Stockholm. TRITA-SCI-FOU 2019:45 • ISBN 978-91-7873-318-7 "O frati," dissi, "che per cento milia perigli siete giunti a l’occidente, a questa tanto picciola vigilia d’i nostri sensi ch’é del rimanente non vogliate negar l’esperïenza, di retro al sol, del mondo sanza gente. Considerate la vostra semenza: fatti non foste a viver come bruti, ma per seguir virtute e canoscenza". Dante Alighieri. Commedia. Inferno – Canto XXVI. "O brothers, who amid a hundred thousand Perils," I said, "have come unto the West, To this so inconsiderable vigil Which is remaining of your senses still, Be ye unwilling to deny the knowledge, Following the sun, of the unpeopled world. Consider ye the seed from which ye sprang; Ye were not made to live like unto brutes, But for pursuit of virtue and of knowledge" Dante Alighieri. Commedia. Inferno – Canto XXVI. Translated by Henry Wadsworth Longfellow. Abstract Nonlinear optics (NLO) plays a major role in the modern world: nonlin- ear optical phenomena have been observed in a wavelength range going from the deep infrared to the extreme ultraviolet, to THz radiation. The optical nonlinearities can be found in crystals, amorphous materials, polymers, liquid crystals, liquids, organic materials, and even gases and plasmas.
    [Show full text]