1 Light Emitting Diodes and Solid-State Lighting Solid-State Lighting

Total Page:16

File Type:pdf, Size:1020Kb

1 Light Emitting Diodes and Solid-State Lighting Solid-State Lighting Light Emitting Diodes and Solid-State Lighting E. Fred Schubert Department of Electrical, Computer, and Systems Engineering Department of Physics, Applied Physics, and Astronomy Rensselaer Polytechnic Institute, Troy, NY 12180 Phone: 518-276-8775 Email: [email protected] Internet: www. LightEmittingDiodes. org 1 of 164 Solid-state lighting Inorganic devices: • Semiconductor plus phosphor illumination devices • All-semiconductor-based illumination devices Organic devices: • Remarkable successes in low-power devices (Active matrix OLED monitors, thin-film transistors, etc.) Comp. Semiconductors, 2006 • Substantial effort is underway to demonstrate high-power devices • Anticipated manufacturing cost and luminance of organic devices are orders of magnitude different from inorganic devices Predicted growth of LED market 2 of 164 1 OLED versus LED OtOpto Tec hCorp. OCOsram Corp. OLEDs are area sources LEDs are point sources They do do not blind They are blindingly bright Suitable for large-area sources Suitable for imaging-optics applications Luminance of OLEDs: 102 –104 cd/m2 Luminance of LEDs: 106 – 107 cd/m2 Luminance of OLEDs is about 4 orders of magnitude lower OLED manufacturing cost per unit area must be 104 lower OLEDs LEDs Low-cost reel-to-reel manufacturing Expensive epitaxial growth 3 of 164 Quantification of solid-state lighting benefits Energy benefits • 22 % of electricity used for lighting • LED-based lighting can be 20 more efficient than incandescent and 5 more efficient than fluorescent lighting Environmental and economic benefits • Reduction of CO2 emissions, a global warming gas • Reduction of SO2 emissions, acid rain • Reduction of Hg emissions by coal-burning power plants • Reduction of hazardous Hg in homes Financial benefits • Electrical energy cost reduction, but also savings resulting from less pollution, global warming Hg Cause: SO Cause: CO2 2 CO2 ,SO2, NOx, Hg, U Cause: Waste heat and acid rain Antarctica Czech Republic Switzerland United States 4 of 164 2 Quantification of benefits Global benefits enabled by solid-state lighting technology over period of 10 years. First numeric value in each box represents annual US value. The USA uses about ¼ of world’s energy. Savings under “11% scenario” Reduction in total energy consumption 43.01 1018 J 11% 4 10 = = 189.2 1018 J Reduction in electrical energy consumption 457.8 TWh 4 10 = = 18,310 TWh = 65.92 1018 J Financial savings 45.78 109 $ 4 10 = = 1,831 109 $ Reduction in CO2 emission 267.0 Mt 4 10 = 10.68 Gt Reduction of crude-oil consumption (1 barrel = 159 24.07 106 barrels 4 10 = = 962.4 106 liters) barrels Number of power plants not needed 70 4 = 280 et al Reports on Progress (*) 1.0 PWh = 1000 TWh = 11.05 PBtu = 11.05 quadrillion Btu “=” 0.1731 Pg of C = 173.1 Mtons of C Schubert ., 1kgofC“=”[(12amu+2 16 amu) / 12 amu] kg of CO2 = 3.667 kg of CO2 in Physics 69, 3069 (2006) 5 of 164 History of LEDs Henry Joseph Round (1881 – 1966) 1907: First observation of electroluminescence 1907: First LED LED was made of SiC, carborundum, an abrasive material Henry Joseph Round 6 of 164 3 Light-Emitting Diode – 1924 – SiC – Lossev Oleg Vladimirovich Lossev (1903 – 1942) Brilliant scientist who published first paper at the age of 20 years The Lossevs were noble family of a Russian Imperial Army officer Lossev made first detailed study of electroluminescence in SiC Lossev concluded that luminescence is no heat glow (incandescence) Lossev noted similarity to vacuum gas discharge Oleg Vladimirovich Lossev SiC – Carborundum 7 of 164 Light-Emitting Diode – 1924 – SiC – Lossev Oleg V. Lossev noted light emission for forward and reverse voltage Measurement period 1924 – 1928 First photograph of LED Lossev’s I-V characteristic 8 of 164 4 Light emission in first LED First LED did not have pn junction! Light was generated by either minority carrier injection (forward) or avalanching (reverse bias) “Beginner’s luck” 9 of 164 History of AlGaAs IR and red LEDs There is lattice mismatch between AlGaAs and GaAs Growth by liquid phase epitaxy (LPE) Growth technique to date: Organometallic vapor Phase epitaxy 10 of 164 5 One of the first application of LEDs LEDs served to verify function of printed circuit boards (PCBs) LEDs served to show status of central processing unit (CPU) 11 of 164 History of GaP red and green LEDs There are direct-gap and indirect-gap semiconductors GaAs is direct but GaP is indirect Iso-electronic impurities (such as N and Zn-O) enable light emission 12 of 164 6 Red GaP LEDs N results in green emission Zn-O results in red emission However, efficiency is limited 13 of 164 Application for GaP:N green LEDs Dial pad illumination Telephone company (AT&T) decided that green is better color than red 14 of 164 7 LEDs in calculators LEDs were used in first generation of calculators Displayed numbers could not be seen in bright daylight LEDs consumed so much power that all calculators had rechargeable batteries 15 of 164 History of GaN blue, green, and white light emitters Blue emission in GaN in 1972, Maruska et al., 1972 However, no p-doping attained Devices were developed by RCA for three-color flat-panel display applications to replace cathode ray tubes (CRTs) Nichia Corporation (Japan) was instrumental in blue LED development Dr. Shuji Nakamura lead of development 16 of 164 8 Applications of green LEDs High-brightness LEDs for outdoor applications 17 of 164 History of AlGaInP visible LEDs Hewlett-Packard Corporation and Toshiba Corporation developed first high-brightness AlGaInP LEDs AlGaInP suited for red, orange, yellow, and yellow-green emitters 18 of 164 9 Recent applications High power applications 19 of 164 Radiative and nonradiative recombination Recombination rate is proportional to the product of the concentrations of electrons and holes R= B n p where B = bimolecular recombination coefficient n = electron concentration p = hole concentration 20 of 164 10 Radiative electron-hole recombination n n n p p p 0 and 0 n free electron concentration n0 equilibrium free electron concentration n excess electron concentration n p R d d Bnp dt dt R recombination rate per cm3 per s B bimolecular recombination coefficient 21 of 164 Carrier decay (low excitation) B n p t n t n ()0 0 ( )0 e B n p 1 0 0 carrier lifetime B bimolecular recombination coefficient 22 of 164 11 Radiative recombination for low-level excitation Radiative lifetimes determine switch-on and switch-off times 23 of 164 Recombination lifetime: Theory versus experiment Radiative lifetime decreases with doping concentration 24 of 164 12 Nonradiative recombination in the bulk Generation of heat competes with generation of light This is a very fundamental issue 25 of 164 Recombination mechanisms Recombination via deep levels Auger recombination Radiative recombination 26 of 164 13 Visualization of defects • DkDark spo ts are c lus ters o dfftfdefects • Dark spots are dark because lack of radiative recombination 27 of 164 Shockley-Read recombination p n n p np R 0 0 SR N v 1 n n n N v 1 p p p t p p 0 1 t n n 0 1 p n n 1 0 0 N v 1 n n n N v 1 p p p t p p 0 1 t n n 0 1 C p n S F E E V 1 1 C T Fi S n D1 T n 1 cosh D T i 0 n 0 HG E kT UXW E 2 i U • Mid-gap levels are effective non-radiative recombination centers 28 of 164 14 Nonradiative recombination at surfaces Surface recombination Surface recombination velocity 29 of 164 Surface recombination F S x L V n exp( /n ) n() x n n() x n n G1 W 0 0 LS H n n X S surface recombination velocity x distance from semiconductor surface Ln carrier diffusion length Surface recombination velocities of semiconductors GaAs S = 106 cm/s GaP S = 106 cm/s InP S = 103 cm/s GaN S = 103 cm/s Si S = 101 cm/s 30 of 164 15 Demonstration of surface recombination • Making surface recombination “visible” 31 of 164 Competition: radiative & nonradiative recombination 1 1 1 r nr 1 r int 1 1 r nr carrier lifetime nr nonradiative carrier lifetime r radiative carrier lifetime int internal quantum efficiency 32 of 164 16 LED basics: Electrical properties Shockley equation for p-n junction diodes C D S D p D T eV kT I e A p n n e – 1 D n0 p0 T E p n U C D 2 2 S D p n D n T eV kT e A i n i e – 1 D N N T E p D n A U I eV kkT s e – 1 I where s is the saturation current 33 of 164 P-n junction band diagram 34 of 164 17 Diode current-voltage characteristics Forward voltage is approximately equal to Eg / e 35 of 164 Diode forward voltage UV-LEDs frequently show excess forward voltage 36 of 164 18 Deviations from ideal I-V characteristic eV n kT II ()ideal s e VIR e V IR n kT I s I e ()()s ideal R s p nideal ideality factor Rs parasitic series resistance Rp parasitic parallel resistance 37 of 164 Non-ideal I-V characteristics Problem areas of diode can be identified from I-V characteristic 38 of 164 19 Methods to determine series resistance Method shown above suitable for series resistance measurement At high currents, diode I-V becomes linear due to dominance of series resistance. Diode series resistance can be extracted in linear regime 39 of 164 Carrier distribution in pn homo- and heterojunctions Double heterostructure enables high carrier concentrations in active region • A high efficiency results 40 of 164 20 Carrier overflow in double heterostructures Carrier leakage out of active region 41 of 164 Saturation of output power due to leakage A larger number of QWs reduce leakage 42 of 164 21 Electron blocking layers Electron blocking layer Hole blocking layer Which of the two would be more effective? 43 of 164 Diode forward voltage V h e E e = / g / E EE EE V g IR C 0 V 0 e s e e I R s resistive loss E –E C 0 electron energy loss upon injection into quantum well E –E V 0 hole energy loss upon injection into quantum well 44 of 164 22 LED basics: Optical properties Internal, extraction, external, and power efficiency P h number of photons emitted from active region per second int /() int number of electrons injected into LED per second I / e number of photons emitted into free space per second extraction number of photons emitted from active region per second P h number of photons emitted into free space per sec.
Recommended publications
  • Fundamentals of Microelectronics Chapter 3 Diode Circuits
    9/17/2010 Fundamentals of Microelectronics CH1 Why Microelectronics? CH2 Basic Physics of Semiconductors CH3 Diode Circuits CH4 Physics of Bipolar Transistors CH5 Bipolar Amplifiers CH6 Physics of MOS Transistors CH7 CMOS Amplifiers CH8 Operational Amplifier As A Black Box 1 Chapter 3 Diode Circuits 3.1 Ideal Diode 3.2 PN Junction as a Diode 3.3 Applications of Diodes 2 1 9/17/2010 Diode Circuits After we have studied in detail the physics of a diode, it is time to study its behavior as a circuit element and its many applications. CH3 Diode Circuits 3 Diode’s Application: Cell Phone Charger An important application of diode is chargers. Diode acts as the black box (after transformer) that passes only the positive half of the stepped-down sinusoid. CH3 Diode Circuits 4 2 9/17/2010 Diode’s Action in The Black Box (Ideal Diode) The diode behaves as a short circuit during the positive half cycle (voltage across it tends to exceed zero), and an open circuit during the negative half cycle (voltage across it is less than zero). CH3 Diode Circuits 5 Ideal Diode In an ideal diode, if the voltage across it tends to exceed zero, current flows. It is analogous to a water pipe that allows water to flow in only one direction. CH3 Diode Circuits 6 3 9/17/2010 Diodes in Series Diodes cannot be connected in series randomly. For the circuits above, only a) can conduct current from A to C. CH3 Diode Circuits 7 IV Characteristics of an Ideal Diode V V R = 0⇒ I = = ∞ R = ∞⇒ I = = 0 R R If the voltage across anode and cathode is greater than zero, the resistance of an ideal diode is zero and current becomes infinite.
    [Show full text]
  • Article Soot Photometer Using Supervised Machine Learning
    Atmos. Meas. Tech., 12, 3885–3906, 2019 https://doi.org/10.5194/amt-12-3885-2019 © Author(s) 2019. This work is distributed under the Creative Commons Attribution 4.0 License. Classification of iron oxide aerosols by a single particle soot photometer using supervised machine learning Kara D. Lamb1,2 1Cooperative Institute for Research in Environmental Sciences, University of Colorado Boulder, Boulder, CO, USA 2NOAA Earth System Research Laboratory Chemical Sciences Division, Boulder, CO, USA Correspondence: Kara D. Lamb ([email protected]) Received: 15 March 2019 – Discussion started: 22 March 2019 Revised: 20 June 2019 – Accepted: 21 June 2019 – Published: 15 July 2019 Abstract. Single particle soot photometers (SP2) use laser- each class are compared with the true class for those particles induced incandescence to detect aerosols on a single particle to estimate generalization performance. While the specific basis. SP2s that have been modified to provide greater spec- class approach performed well for rBC and Fe3O4 (≥ 99 % tral contrast between their narrow and broad-band incandes- of these aerosols are correctly identified), its classification of cent detectors have previously been used to characterize both other aerosol types is significantly worse (only 47 %–66 % refractory black carbon (rBC) and light-absorbing metallic of other particles are correctly identified). Using the broader aerosols, including iron oxides (FeOx). However, single par- class approach, we find a classification accuracy of 99 % for ticles cannot be unambiguously identified from their incan- FeOx samples measured in the laboratory. The method al- descent peak height (a function of particle mass) and color lows for classification of FeOx as anthropogenic or dust-like ratio (a measure of blackbody temperature) alone.
    [Show full text]
  • Introduction 1
    1 1 Introduction . ex arte calcinati, et illuminato aeri [ . properly calcinated, and illuminated seu solis radiis, seu fl ammae either by sunlight or fl ames, they conceive fulgoribus expositi, lucem inde sine light from themselves without heat; . ] calore concipiunt in sese; . Licetus, 1640 (about the Bologna stone) 1.1 What Is Luminescence? The word luminescence, which comes from the Latin (lumen = light) was fi rst introduced as luminescenz by the physicist and science historian Eilhardt Wiede- mann in 1888, to describe “ all those phenomena of light which are not solely conditioned by the rise in temperature,” as opposed to incandescence. Lumines- cence is often considered as cold light whereas incandescence is hot light. Luminescence is more precisely defi ned as follows: spontaneous emission of radia- tion from an electronically excited species or from a vibrationally excited species not in thermal equilibrium with its environment. 1) The various types of lumines- cence are classifi ed according to the mode of excitation (see Table 1.1 ). Luminescent compounds can be of very different kinds: • Organic compounds : aromatic hydrocarbons (naphthalene, anthracene, phenan- threne, pyrene, perylene, porphyrins, phtalocyanins, etc.) and derivatives, dyes (fl uorescein, rhodamines, coumarins, oxazines), polyenes, diphenylpolyenes, some amino acids (tryptophan, tyrosine, phenylalanine), etc. + 3 + 3 + • Inorganic compounds : uranyl ion (UO 2 ), lanthanide ions (e.g., Eu , Tb ), doped glasses (e.g., with Nd, Mn, Ce, Sn, Cu, Ag), crystals (ZnS, CdS, ZnSe, CdSe, 3 + GaS, GaP, Al 2 O3 /Cr (ruby)), semiconductor nanocrystals (e.g., CdSe), metal clusters, carbon nanotubes and some fullerenes, etc. 1) Braslavsky , S. et al . ( 2007 ) Glossary of terms used in photochemistry , Pure Appl.
    [Show full text]
  • Vacuum Tube Theory, a Basics Tutorial – Page 1
    Vacuum Tube Theory, a Basics Tutorial – Page 1 Vacuum Tubes or Thermionic Valves come in many forms including the Diode, Triode, Tetrode, Pentode, Heptode and many more. These tubes have been manufactured by the millions in years gone by and even today the basic technology finds applications in today's electronics scene. It was the vacuum tube that first opened the way to what we know as electronics today, enabling first rectifiers and then active devices to be made and used. Although Vacuum Tube technology may appear to be dated in the highly semiconductor orientated electronics industry, many Vacuum Tubes are still used today in applications ranging from vintage wireless sets to high power radio transmitters. Until recently the most widely used thermionic device was the Cathode Ray Tube that was still manufactured by the million for use in television sets, computer monitors, oscilloscopes and a variety of other electronic equipment. Concept of thermionic emission Thermionic basics The simplest form of vacuum tube is the Diode. It is ideal to use this as the first building block for explanations of the technology. It consists of two electrodes - a Cathode and an Anode held within an evacuated glass bulb, connections being made to them through the glass envelope. If a Cathode is heated, it is found that electrons from the Cathode become increasingly active and as the temperature increases they can actually leave the Cathode and enter the surrounding space. When an electron leaves the Cathode it leaves behind a positive charge, equal but opposite to that of the electron. In fact there are many millions of electrons leaving the Cathode.
    [Show full text]
  • Diodes As Rectifiers +
    Diodes as Rectifiers As previously mentioned, diodes can be used to convert alternating current (AC) to direct current (DC). Shown below is a representative schematic of a simple DC power supply similar to a au- tomobile battery charger. The way in which the diode rectifier is used results in what is called a half-wave rectifier. 0V 35.6Vpp 167V 0V pp 17.1Vp 0V T1 D1 Wallplug 1N4001 negative half−wave is 110VAC R1 resistive load removed by diode D1 D1 120 to 12.6VAC − stepdown transformer + D2 D2 input from RL input from RL transformer transformer (positive half−cycle) Figure 1: Half-Wave Rectifier Schematic (negative half−cycle) − D3 + D3 The input transformer steps the input voltage down from 110VAC(rms) to 12.6VAC(rms). The D4 D4 diode converts the AC voltage to DC by removing theD1 and negative D3 goingD1 and D3 part of the input sine wave. The result is a pulsating DC output waveform which is not ideal except for17.1V simplep applications 0V such as battery chargers as the voltage goes to zero for oneD2 have and D4 of every cycle. What we would D1 D1 v_out like is a DC output that is more consistent;T1 a waveform more like a battery what we have here. T1 1 D2 D2 C1 Wallplug R1 Wallplug R1 We need a way to use the negative half-cycle of theresistive sine load wave to to fill in between the pulses 50uF 1K 110VAC 110VAC created by the positive half-waves. This would give us a more consistent output voltage.
    [Show full text]
  • Lecture 3: Diodes and Transistors
    2.996/6.971 Biomedical Devices Design Laboratory Lecture 3: Diodes and Transistors Instructor: Hong Ma Sept. 17, 2007 Diode Behavior • Forward bias – Exponential behavior • Reverse bias I – Breakdown – Controlled breakdown Æ Zeners VZ = Zener knee voltage Compressed -VZ scale 0V 0.7 V V ⎛⎞V Breakdown V IV()= I et − 1 S ⎜⎟ ⎝⎠ kT V = t Q Types of Diode • Silicon diode (0.7V turn-on) • Schottky diode (0.3V turn-on) • LED (Light-Emitting Diode) (0.7-5V) • Photodiode • Zener • Transient Voltage Suppressor Silicon Diode • 0.7V turn-on • Important specs: – Maximum forward current – Reverse leakage current – Reverse breakdown voltage • Typical parts: Part # IF, max IR VR, max Cost 1N914 200mA 25nA at 20V 100 ~$0.007 1N4001 1A 5µA at 50V 50V ~$0.02 Schottky Diode • Metal-semiconductor junction • ~0.3V turn-on • Often used in power applications • Fast switching – no reverse recovery time • Limitation: reverse leakage current is higher – New SiC Schottky diodes have lower reverse leakage Reverse Recovery Time Test Jig Reverse Recovery Test Results • Device tested: 2N4004 diode Light Emitting Diode (LED) • Turn-on voltage from 0.7V to 5V • ~5 years ago: blue and white LEDs • Recently: high power LEDs for lighting • Need to limit current LEDs in Parallel V R ⎛⎞ Vt IV()= IS ⎜⎟ e − 1 VS = 3.3V ⎜⎟ ⎝⎠ •IS is strongly dependent on temp. • Resistance decreases R R R with increasing V = 3.3V S temperature • “Power Hogging” Photodiode • Photons generate electron-hole pairs • Apply reverse bias voltage to increase sensitivity • Key specifications: – Sensitivity
    [Show full text]
  • CSE- Module-3: SEMICONDUCTOR LIGHT EMITTING DIODE :LED (5Lectures)
    CSE-Module- 3:LED PHYSICS CSE- Module-3: SEMICONDUCTOR LIGHT EMITTING DIODE :LED (5Lectures) Light Emitting Diodes (LEDs) Light Emitting Diodes (LEDs) are semiconductors p-n junction operating under proper forward biased conditions and are capable of emitting external spontaneous radiations in the visible range (370 nm to 770 nm) or the nearby ultraviolet and infrared regions of the electromagnetic spectrum General Structure LEDs are special diodes that emit light when connected in a circuit. They are frequently used as “pilot light” in electronic appliances in to indicate whether the circuit is closed or not. The structure and circuit symbol is shown in Fig.1. The two wires extending below the LED epoxy enclose or the “bulb” indicate how the LED should be connected into a circuit or not. The negative side of the LED is indicated in two ways (1) by the flat side of the bulb and (2) by the shorter of the two wires extending from the LED. The negative lead should be connected to the negative terminal of a battery. LEDs operate at relative low voltage between 1 and 4 volts, and draw current between 10 and 40 milliamperes. Voltages and Fig.-1 : Structure of LED current substantially above these values can melt a LED chip. The most important part of a light emitting diode (LED) is the semiconductor chip located in the centre of the bulb and is attached to the 1 CSE-Module- 3:LED top of the anvil. The chip has two regions separated by a junction. The p- region is dominated by positive electric charges, and the n-region is dominated by negative electric charges.
    [Show full text]
  • 2. Making Fires Burn Or Go out 1: Introduction to the Fire Triangle
    2. Making Fires Burn or Go Out 1: Introduction to the Fire Triangle Lesson Overview: In this activity, students describe and organize what they already know Subjects: Science, Mathematics, Writing, about fire so it fits into the conceptual model of Speaking and Listening, Health and the Fire Triangle. They examine the geometric Safety stability of a triangle and how that property Duration: one half-hour session applies to fire. Group size: Whole class. Students work in groups of 2-3. Lesson Goal: Increase students’ understanding of Setting: Indoors how fires burn and why they go out. Vocabulary: Fire Triangle, fuel, heat, ignition, oxygen, model Objectives: • Students can construct a triangle out of toothpicks and gumdrops, and can label its legs with the three components of the Fire Triangle. • Students can demonstrate that removing one side of the triangle makes it collapse. • Students can identify the component(s) of the Fire Triangle that are removed in various scenarios, and explain how this makes the fire go out. Standards: 1st 2nd 3rd 4th 5th CCSS Writing 2, 7, 8 2, 7, 8 2, 7, 10 2,7, 9, 10 2,7, 9, 10 Speaking/Listening 1, 2, 4, 6 1, 2, 4, 6 1, 2, 4, 6 1, 2, 4, 6 1, 2, 4, 6 1, 2, 3, 4, Language 1, 2, 4, 6 1, 2, 4, 6 6 1, 2, 3, 4, 6 1, 2, 3, 4, 6 MP.4, MP.4, MP.4, MP.4, Math MP.5 MP.5, MP.5 MP.5 MP.4, MP.5 Matter and Its PS1.A, NGSS Interactions PS1.B PS1.B From Molecules to Organisms: Structure/Processes LS1.C Engineering Design ETS1.B ETS1.B EEEGL Strand 1 A, B, C, E, F, G A, B, C, E, F, G Teacher Background: This activity explores the chemistry of combustion as described by a conceptual model called the Fire Triangle.
    [Show full text]
  • Energy Efficiency Lighting Hearing Committee On
    S. HRG. 110–195 ENERGY EFFICIENCY LIGHTING HEARING BEFORE THE COMMITTEE ON ENERGY AND NATURAL RESOURCES UNITED STATES SENATE ONE HUNDRED TENTH CONGRESS FIRST SESSION TO RECEIVE TESTIMONY ON THE STATUS OF ENERGY EFFICIENT LIGHT- ING TECHNOLOGIES AND ON S. 2017, THE ENERGY EFFICIENT LIGHT- ING FOR A BRIGHTER TOMORROW ACT SEPTEMBER 12, 2007 ( Printed for the use of the Committee on Energy and Natural Resources U.S. GOVERNMENT PRINTING OFFICE 39–385 PDF WASHINGTON : 2007 For sale by the Superintendent of Documents, U.S. Government Printing Office Internet: bookstore.gpo.gov Phone: toll free (866) 512–1800; DC area (202) 512–1800 Fax: (202) 512–2104 Mail: Stop IDCC, Washington, DC 20402–0001 VerDate 0ct 09 2002 11:58 Feb 20, 2008 Jkt 040443 PO 00000 Frm 00001 Fmt 5011 Sfmt 5011 G:\DOCS\39385.XXX SENERGY2 PsN: MONICA COMMITTEE ON ENERGY AND NATURAL RESOURCES JEFF BINGAMAN, New Mexico, Chairman DANIEL K. AKAKA, Hawaii PETE V. DOMENICI, New Mexico BYRON L. DORGAN, North Dakota LARRY E. CRAIG, Idaho RON WYDEN, Oregon LISA MURKOWSKI, Alaska TIM JOHNSON, South Dakota RICHARD BURR, North Carolina MARY L. LANDRIEU, Louisiana JIM DEMINT, South Carolina MARIA CANTWELL, Washington BOB CORKER, Tennessee KEN SALAZAR, Colorado JOHN BARRASSO, Wyoming ROBERT MENENDEZ, New Jersey JEFF SESSIONS, Alabama BLANCHE L. LINCOLN, Arkansas GORDON H. SMITH, Oregon BERNARD SANDERS, Vermont JIM BUNNING, Kentucky JON TESTER, Montana MEL MARTINEZ, Florida ROBERT M. SIMON, Staff Director SAM E. FOWLER, Chief Counsel FRANK MACCHIAROLA, Republican Staff Director JUDITH K. PENSABENE, Republican Chief Counsel (II) VerDate 0ct 09 2002 11:58 Feb 20, 2008 Jkt 040443 PO 00000 Frm 00002 Fmt 5904 Sfmt 5904 G:\DOCS\39385.XXX SENERGY2 PsN: MONICA C O N T E N T S STATEMENTS Page Bingaman, Hon.
    [Show full text]
  • ECE 255, Diodes and Rectifiers
    ECE 255, Diodes and Rectifiers 23 January 2018 In this lecture, we will discuss the use of Zener diode as voltage regulators, diode as rectifiers, and as clamping circuits. 1 Zener Diodes In the reverse biased operation, a Zener diode displays a voltage breakdown where the current rapidly increases within a small range of voltage change. This property can be used to limit the voltage within a small range for a large range of current. The symbol for a Zener diode is shown in Figure 1. Figure 1: The symbol for a Zener diode under reverse biased (Courtesy of Sedra and Smith). Figure 2 shows the i-v relation of a Zener diode near its operating point where the diode is in the breakdown regime. The beginning of the breakdown point is labeled by the current IZK also called the knee current. The oper- ating point can be approximated by an incremental resistance, or dynamic resistance described by the reciprocal of the slope of the point. Since the slope, dI proportional to dV , is large, the incremental resistance is small, generally on the order of a few ohms to a few tens of ohms. The spec sheet usually gives the voltage of the diode at a specified test current IZT . Printed on March 14, 2018 at 10 : 29: W.C. Chew and S.K. Gupta. 1 Figure 2: The i-v characteristic of a Zener diode at its operating point Q (Cour- tesy of Sedra and Smith). The diode can be fabricated to have breakdown voltage of a few volts to a few hundred volts.
    [Show full text]
  • Biofluorescence
    Things That Glow In The Dark Classroom Activities That Explore Spectra and Fluorescence Linda Shore [email protected] “Hot Topics: Research Revelations from the Biotech Revolution” Saturday, April 19, 2008 Caltech-Exploratorium Learning Lab (CELL) Workshop Special Guest: Dr. Rusty Lansford, Senior Scientist and Instructor, Caltech Contents Exploring Spectra – Using a spectrascope to examine many different kinds of common continuous, emission, and absorption spectra. Luminescence – A complete description of many different examples of luminescence in the natural and engineered world. Exploratorium Teacher Institute Page 1 © 2008 Exploratorium, all rights reserved Exploring Spectra (by Paul Doherty and Linda Shore) Using a spectrometer The project Star spectrometer can be used to look at the spectra of many different sources. It is available from Learning Technologies, for under $20. Learning Technologies, Inc., 59 Walden St., Cambridge, MA 02140 You can also build your own spectroscope. http://www.exo.net/~pauld/activities/CDspectrometer/cdspectrometer.html Incandescent light An incandescent light has a continuous spectrum with all visible colors present. There are no bright lines and no dark lines in the spectrum. This is one of the most important spectra, a blackbody spectrum emitted by a hot object. The blackbody spectrum is a function of temperature, cooler objects emit redder light, hotter objects white or even bluish light. Fluorescent light The spectrum of a fluorescent light has bright lines and a continuous spectrum. The bright lines come from mercury gas inside the tube while the continuous spectrum comes from the phosphor coating lining the interior of the tube. Exploratorium Teacher Institute Page 2 © 2008 Exploratorium, all rights reserved CLF Light There is a new kind of fluorescent called a CFL (compact fluorescent lamp).
    [Show full text]
  • Resistors, Diodes, Transistors, and the Semiconductor Value of a Resistor
    Resistors, Diodes, Transistors, and the Semiconductor Value of a Resistor Most resistors look like the following: A Four-Band Resistor As you can see, there are four color-coded bands on the resistor. The value of the resistor is encoded into them. We will follow the procedure below to decode this value. • When determining the value of a resistor, orient it so the gold or silver band is on the right, as shown above. • You can now decode what resistance value the above resistor has by using the table on the following page. • We start on the left with the first band, which is BLUE in this case. So the first digit of the resistor value is 6 as indicated in the table. • Then we move to the next band to the right, which is GREEN in this case. So the second digit of the resistor value is 5 as indicated in the table. • The next band to the right, the third one, is RED. This is the multiplier of the resistor value, which is 100 as indicated in the table. • Finally, the last band on the right is the GOLD band. This is the tolerance of the resistor value, which is 5%. The fourth band always indicates the tolerance of the resistor. • We now put the first digit and the second digit next to each other to create a value. In this case, it’s 65. 6 next to 5 is 65. • Then we multiply that by the multiplier, which is 100. 65 x 100 = 6,500. • And the last band tells us that there is a 5% tolerance on the total of 6500.
    [Show full text]