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LEDs-an Overview of the State of the Art in Technology and Application

Description: Solid state lighting in the form of Light Emitting Diodes (LEDs) is bringing new sources with different operating characteristics to the market. With the control in dimension, optics, intensity and color, these sources have the potential to transform the way we use light. This paper will review the recent improvements in performance that have been achieved by these devices, focusing on those product attributes identified as being critical to end users. The paper will conclude with a considerati… more
Date: March 1, 2002
Creator: Johnson, Stephen
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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High Voltage GaN Schottky Rectifiers

Description: Mesa and planar GaN Schottky diode rectifiers with reverse breakdown voltages (V{sub RB}) up to 550V and >2000V, respectively, have been fabricated. The on-state resistance, R{sub ON}, was 6m{Omega}{center_dot} cm{sup 2} and 0.8{Omega}cm{sup 2}, respectively, producing figure-of-merit values for (V{sub RB}){sup 2}/R{sub ON} in the range 5-48 MW{center_dot}cm{sup -2}. At low biases the reverse leakage current was proportional to the size of the rectifying contact perimeter, while at high bias… more
Date: October 25, 1999
Creator: Cao, X. A.; Cho, H.; Chu, S. N. G.; Chuo, C. C.; Chyi, J. I.; Dang, G. T. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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PHOTOINDUCED CURRENTS IN CDZNTE CRYSTALS AS A FUNCTION OF ILLUMINATION WAVELENGTH

Description: We report variations in the currents of CdZnTe semiconductor crystals during exposure to a series of light emitting diodes of various wavelengths ranging from 470 to 950 nm. The changes in the steady-state current of one CdZnTe crystal with and without illumination along with the time dependence of the illumination effects are discussed. Analysis of the de-trapping and transient bulk currents during and after optical excitation yield insight into the behaviour of charge traps within the crystal… more
Date: April 23, 2012
Creator: Teague, L.; Washington, A. & Duff, M.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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A long pulse high-power diode based on a microelectronic emitter

Description: Microelectronic cathode emitter technology being developed at Sandia for supplying continuous low current for flat panel displays appears to be a promising technology for providing high currents when operated in a pulsed, higher voltage mode. If currents in excess of one amp per square centimeter could be produced for tens of microseconds at several kilohertz repetition rate, important applications in such as large volume food or waste sterilization in situ detection, and high power microwave p… more
Date: November 1, 1995
Creator: Marder, B.; Clark, C.; Walko, R. & Fleming, J.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Degradation of blue AlGaN/InGaN/GaN LEDs subjected to high current pulses

Description: Short-wavelength, visible-light emitting optoelectronic devices are needed for a wide range of commercial applications, including high-density optical data storage, full-color displays, and underwater communications. In 1994, high-brightness blue LEDs based on gallium nitride and related compounds (InGaN/AlGaN) were introduced by Nichia Chemical Industries. The Nichia diodes are 100 times brighter than the previously available SiC blue LEDs. Group-III nitrides combine a wide, direct bandgap wit… more
Date: December 31, 1994
Creator: Barton, D. L.; Zeller, J.; Phillips, B. S.; Chiu, P. C.; Askar, S.; Lee, D. S. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Work Functions of the transition Metals and Metal Silicides

Description: The work functions of polycrystalline metals are often used to systematize Schottky barrier height data for rectifying contacts to semiconductors. Rectifying contacts to silicon devices are predominantly formed using conductive metal silicides with work functions which are not as well characterized as metal work functions. The present work has two objectives. First, it classifies the transition metals using correlations between the metal work function and the atomic chemical potential. Second, … more
Date: February 15, 1999
Creator: Drummond, T.J.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Design and performance of nitride-based ultraviolet (UV) LEDs

Description: The authors overview several of the challenges in achieving high efficiency nitride-based UV (< 400 nm) LEDs. The issue of optical efficiency is presented through temperature-dependent photoluminescence studies of various UV active regions. These studies demonstrate enhanced optical efficiencies for active regions with In-containing alloys (InGaN, AlInGaN). The authors compare the performance of two distinct UV LED structures. GaN/AlGaN quantum well LEDs with {lambda} < 360 nm emission ha… more
Date: April 24, 2000
Creator: Crawford, Mary H. & Han, Jung
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Applications of CdTe to nuclear medicine. Annual report, February 1, 1978-January 31, 1979

Description: The use of CdTe radiation detectors in medical applications continues to become more widespread. During this contract period a CdTe detector as small as 1 mm/sup 3/ was inserted into a bronchoscope while a CdTe array as large as 4200 mm/sup 3/ was used as a prototype gamma camera. Portable battery powered instrumentation was also developed to further enhance the versatility of the CdTe concept. One of these electronic packages which is used in several hospitals is illustrated. The unit provides… more
Date: January 1, 1979
Creator: Entine, G
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Novel Approaches to High-Efficiency III-V Nitride Heterostructure Emitters for Next-Generation Lighting Applications Annual Report: 2005

Description: We report research activities and technical progress on the development of high-efficiency long wavelength ({lambda} {approx} 540nm) green light emitting diodes which covers the second year of the three-year program ''Novel approaches to high-efficiency III-V nitride heterostructure emitters for next-generation lighting applications''. The second year activities were focused on the development of p-type layer that has less/no detrimental thermal annealing effect on green LED active region as we… more
Date: January 1, 2006
Creator: Dupuis, Russell D.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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High Efficiency LED Lamp for Solid-State Lighting

Description: This report contains a summary of technical achievements during a three-year project to demonstrate high efficiency, solid-state lamps based on gallium nitride/silicon carbide light-emitting diodes. Novel chip designs and fabrication processes are described for a new type of nitride light-emitting diode with the potential for very high efficiency. This work resulted in the demonstration of blue light-emitting diodes in the one watt class that achieved up to 495 mW of light output at 350 mA driv… more
Date: December 31, 2006
Creator: Ibbetson, James
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Agreement Between Local and Global Measurements of the London Penetration Depth

Description: Recent measurements of the superconducting penetration depth in Ba(Fe{sub 1-x}Co{sub x}){sub 2}As{sub 2} appeared to disagree on the magnitude and curvature of {delta}{lambda}{sub ab}(T), even near optimal doping. These measurements were carried out on different samples grown by different groups. To understand the discrepancy, we use scanning SQUID susceptometry and a tunnel diode resonator to measure the penetration depth in a single sample. The penetration depth observed by the two techniques… more
Date: August 29, 2012
Creator: Lippman, Thomas M.; Kalisky, Beena; Kim, Hyunsoo; Tanatar, Makariy; Budko, Sergey L.; Canfield, Paul C. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Suppression of auger recombination in ""giant"" core/shell nanocrystals

Description: Many potential applications of semiconductor nanocrystals are hindered by nonradiative Auger recombination wherein the electron-hole (exciton) recombination energy is transferred to a third charge carrier. This process severely limits the lifetime and bandwidth of optical gain, leads to large nonradiative losses in light emitting diodes and photovoltaic cells, and is believed to be responsible for intermittency ('blinking') of emission from single nanocrystals. The development of nanostructures… more
Date: January 1, 2009
Creator: Garcia Santamaria, Florencio; Vela, Javier; Schaller, Richard D; Hollingsworth, Jennifer A; Klimov, Victor I & Chen, Yongfen
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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High Efficiency, Illumination Quality OLEDs for Lighting

Description: The goal of the program was to demonstrate a 45 lumen per watt white light device based upon the use of multiple emission colors through the use of solution processing. This performance level is a dramatic extension of the team's previous 15 LPW large area illumination device. The fundamental material system was based upon commercial polymer materials. The team was largely able to achieve these goals, and was able to deliver to DOE a 90 lumen illumination source that had an average performance … more
Date: March 31, 2008
Creator: Shiang, Joseph; Cella, James; Chichak, Kelly; Duggal, Anil; Janora, Kevin; Heller, Chris et al.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Dynamic magnetic susceptibility of systems with long-range magnetic order

Description: The utility of the TDR as an instrument in the study of magnetically ordered materials has been expanded beyond the simple demonstration purposes. Results of static applied magnetic field dependent measurements of the dynamic magnetic susceptibility, ?, of various ferromagnetic (FM) and antiferromagnetic (AFM) materials showing a range of transition temperatures (1-800 K) are presented. Data was collected primarily with a tunnel diode resonator (TDR) at different radio-frequencies ({approx}10-3… more
Date: May 15, 2009
Creator: Vannette, Matthew Dano
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries Government Documents Department
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THz transceiver characterization : LDRD project 139363 final report.

Description: LDRD Project 139363 supported experiments to quantify the performance characteristics of monolithically integrated Schottky diode + quantum cascade laser (QCL) heterodyne mixers at terahertz (THz) frequencies. These integrated mixers are the first all-semiconductor THz devices to successfully incorporate a rectifying diode directly into the optical waveguide of a QCL, obviating the conventional optical coupling between a THz local oscillator and rectifier in a heterodyne mixer system. This inte… more
Date: September 1, 2009
Creator: Nordquist, Christopher Daniel; Wanke, Michael Clement; Cich, Michael Joseph; Reno, John Louis; Fuller, Charles T.; Wendt, Joel Robert et al.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Oleds for General Lighting

Description: The goal of this program was to reduce the long term technical risks that were keeping the lighting industry from embracing and developing organic light-emitting diode (OLED) technology for general illumination. The specific goal was to develop OLEDs for lighting to the point where it was possible to demonstrate a large area white light panel with brightness and light quality comparable to a fluorescence source and with an efficacy comparable to that of an incandescent source. it was recognized… more
Date: February 29, 2004
Creator: Duggal, Anil; Foust, Don; Heller, Chris; Nealon, Bill; Turner, Larry; Shiang, Joe et al.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Electrostatic Discharge (ESD) Protection for a Laser Diode Ignited Actuator

Description: The use of laser diodes in devices to ignite pyrotechnics provides unique new capabilities including the elimination of electrostatic discharge (ESD) pulses entering the device. The Faraday cage formed by the construction of these devices removes the concern of inadvertent ignition of the energetic material. However, the laser diode itself can be damaged by ESD pulses, therefore, to enhance reliability, some protection of the laser diode is necessary. The development of the MC4612 Optical Actua… more
Date: June 1, 2003
Creator: SALAS, FREDERICK J.; SANCHEZ, DANIEL H. & WEINLEIN, JOHN HARVEY
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Reduced mass persistent switches for large superconducting magnets in space

Description: Superconducting magnets in space must operate in the persistent mode. This paper describes the characteristics of low mass niobium titanium persistent switches for low mass superconducting magnets which are designed to quench protect themselves through the quench back process. (The whole coil is driven normal shortly after the quench has started and the magnet stored energy is taken up by the coil and the persistent switch.) The concept Of using a resistor and diode in parallel with the persist… more
Date: August 1, 1992
Creator: Green, M. A.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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The Growth of Mid-Infrared Emitting InAsSb/InAsP Strained-Layer Superlattices Using Metal-Organic Chemical Vapor Deposition

Description: We describe the metal-organic chemical vapor deposition os InAsSb/InAsP strained-layer superlattice (SLS) active regions for use in mid-infrared emitters. These SLSs were grown at 500 {degrees}C, and 200 torr in a horizontal quartz reactor using trimethylindium, triethylantimony, AsH{sub 3}, and PH{sub 3}. By changing the layer thickness and composition we have prepared structures with low temperature ({le}20K) photoluminescence wavelengths ranging from 3.2 to 5.0 {mu}m. Excellent performance w… more
Date: October 1, 1997
Creator: Biefeld, R. M.; Allerman, A. A.; Kurtz, S. R. & Burkhart, J. H.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Blocking diodes and fuses in low-voltage PV systems

Description: Instructions and labels supplied with listed PV modules and the requirements of the National Electrical Code (NEC) dictate that a series fuse shall be used to protect the module against backfeed currents. Few of the hundreds of thousands of low-voltage (12, 24, and 48-volt) stand-alone photovoltaic (PV) power systems use series fuses on each module or string of modules. Tests and simulations at the Southwest Technology Development Institute (TDI) and at Sandia National Laboratories (SNL) have e… more
Date: November 1, 1997
Creator: Wiles, J.C. & King, D.L.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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PIN diode array x-ray imaging. Final Technical report

Description: We have completed constructing an x-ray camera based on a solid state imaging device and have obtained images of Omega laser targets. A Si PIN diode array is used. Objective of this project is to investigate the use of a PIN diode array readout device for obtaining images of 1-20 keV x-ray emission from laser targets. The PIN array detector was successfully used for obtaining hard x-ray images in the high powered laser environment and real time images of the x-ray emission from laser targets.
Date: September 1, 1996
Creator: Jernigan, J.G.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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High-speed vertical cavity surface emitting lasers

Description: High speed modulation and pulsing are reported for oxide-confined vertical cavity surface emitting laser diodes (VCSELs) with inverted doping and proton implantation to reduce the extrinsic limitations.
Date: March 1, 1997
Creator: Lear, K.L.; Ochiai, M. & Hietala, V.M.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Multi-Staged, InAsSb Mid-Infrared Lasers and Light-Emitting Diodes, Grown by MOCVD

Description: Due to lower nonradiative rates, mid-infrared (2-6 micron) lasers with strained, narrow bandgap, Sb-based active regions have the potential to operate at lower current density and higher temperature than competing devices. Superior performance may be achieved through the {open_quotes}band structure engineered{close_quotes} reduction of Auger recombination and the implementation of multi-stage (or {open_quotes}cascaded{close_quotes}) active regions. We describe the first lasers and LEDs utilizin… more
Date: September 1, 1997
Creator: Kurtz, S. R.; Allerman, A. A.; Biefeld, R. M. & Baucom, K. C.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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