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Dissertations / Theses on the topic 'Quantum efficiency'

Author: Grafiati

Published: 4 June 2021

Last updated: 26 July 2025

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1

Özelci, Ersan. "Exploring Fundamental Limits of Quantum Efficiency Measurements Using Quantum Electrodynamics." Doctoral thesis, Humboldt-Universität zu Berlin, 2021. http://dx.doi.org/10.18452/22539.

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Photolumineszenz-Techniken spielen eine wichtige Rolle bei der Charakterisierung verschiedener funktionaler Fluorophore in den Lebens- und Materialwissenschaften, in der Biologie und bis hin zu den Quantentechnologien. Ein entscheidender und wichtiger Parameter für den Vergleich von Fluorophoren ist die Quanteneffizienz, die ein direktes Maß für die Umwandlungseffizienz von absorbierten Photonen in emittierte Photonen darstellt. Diese Größe charakterisiert die Nutzbarkeit von Emittern für Anwendungen in optischen Geräten, Einzelphotonenquellen und im biomedizinischen Bereich. Mehrere Techniken

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2

Wu, Tony Chang-Chi. "Quantum efficiency and fission rate in tetracene." Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/82360.

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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2013.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references (p. 39-40).<br>Using singlet fission in a photovoltaic cell, the theoretical energy conversion efficiency limit is larger than the Shockley-Queisser limit due to two excitons produced with one incident photon. In a singlet fission material, an absorbed photon excites a singlet exciton and then split into two triplet excitons with energy around half of the singlet exciton. Tetracene is a potential candid

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3

Özelci, Ersan [Verfasser]. "Exploring Fundamental Limits of Quantum Efficiency Measurements Using Quantum Electrodynamics / Ersan Özelci." Berlin : Humboldt-Universität zu Berlin, 2021. http://d-nb.info/1229916423/34.

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4

Li, Xing. "Efficiency droop mitigation and quantum efficiency enhancement for nitride Light-Emitting Diodes." VCU Scholars Compass, 2012. http://scholarscompass.vcu.edu/etd/395.

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In the past decade, GaN-based nitrides have had a considerable impact in solid state lighting and high speed high power devices. InGaN-based LEDs have been widely used for all types of displays in TVs, computers, cell phones, etc. More and more high power LEDs have also been introduced in general lighting market. Once widely used, such LEDs could lead to the decrease of worldwide electrical consumption for lighting by more than 50% and reduce total electricity consumption by > 10%. However, there are still challenges for current state-of-the art InGaN-based LEDs, including ‘efficiency droop

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5

Thériault, Olivier. "Analysis of the External Quantum Efficiency of Quantum Dot-enhanced Multijunction Solar Cells." Thesis, Université d'Ottawa / University of Ottawa, 2015. http://hdl.handle.net/10393/32027.

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This thesis focuses on the analysis of the external quantum efficiency of quantum dot-enhanced multi-junction solar cells. Divided in four major parts, it uses the experimental methodology developed in the SUNLAB. At first, a model is introduced to calculate the external quantum efficiency of single and multi-junction solar cells. This model takes into account the semiconductor physics governing the electrical property of the solar cell. It furthermore takes into account the optical transmission and reflection in the semiconductor structure using a transfer matrix method. The calculated curve

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6

Cham, Dit Tham Rakié. "Measurement of relative quantum efficiency of CsI photocathodes." Thesis, McGill University, 1995. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=23874.

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The response of CsI photocathodes widely used in Fast RICH detectors is greatly affected by the environment in which the CsI is deposited. It has been shown in previous studies that the exposure of the CsI to air is detrimental to the CsI photocathode response. In this work we introduce a novel spraying technique where the whole chamber is exposed to nothing but a controlled dry argon atmosphere and the ambient gas environment in which measurements are taken, i.e., methane. All results concerning the CsI are obtained relative to copper. A relative quantum efficiency of 400 to 700 was measured

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7

Bullard, Elizabeth Caryn. "High efficiency photodetection below the quantum noise limit." Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/32842.

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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Physics, 2005.<br>Includes bibliographical references (leaves 49-50).<br>Two low-noise, high quantum efficiency, high bandwidth photodetectors have constructed to form a balanced homodyne detector to detect squeezed light. The detectors have quantum efficiencies of 85% and 90%, a bandwidth of 1MHz, and a dark noise of ... at 1MHz.<br>by Elizabeth Caryn Bullard.<br>S.B.

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8

Maldei, Michael. "Quantum efficiency measurements of a-C:H based photovoltaic cells." Ohio : Ohio University, 1997. http://www.ohiolink.edu/etd/view.cgi?ohiou1177092277.

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9

DUARTE, MARCOS. "Eficiencia quantica de luminescencia de alguns meios laser ativos." reponame:Repositório Institucional do IPEN, 1992. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10305.

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Made available in DSpace on 2014-10-09T12:37:07Z (GMT). No. of bitstreams: 0<br>Made available in DSpace on 2014-10-09T13:56:35Z (GMT). No. of bitstreams: 1 01910.pdf: 4062868 bytes, checksum: 7a2c99911af143a5328f337d491e3f2f (MD5)<br>Dissertacao (Mestrado)<br>IPEN/D<br>Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

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10

Kara, Abdullah. "Quantum efficiency as a function of temperature in metal photocathodes." Monterey, California: Naval Postgraduate School, 2013. http://hdl.handle.net/10945/34684.

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Approved for public release; distribution is unlimited<br>Photocathodes, in which light is used to extract electrons from materials by the photoelectric effect, are the principal electron sources for many linear accelerators and Free Electron Lasers (FELs). There is an increasing interest in the use of superconducting radiofrequency electron guns, which work at cryogenic temperatures, and therefore require photocathodes that work at cryogenic temperatures as well. The primary metric used to quantify photocathode performance is the cathodes Quantum Efficiency (QE), which is the ratio between th

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11

Daboo, Cyrus. "Surface plasmon enhanced quantum efficiency of GaAs-Au Schottky diodes." Thesis, University of Cambridge, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.386416.

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12

Shirasaki, Yasuhiro. "Efficiency loss mechanisms in colloidal quantum-dot light-emitting diodes." Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/82365.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2013.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references (p. 135-147).<br>Saturated and tunable emission colors make colloidal quantum-dot light-emitting diodes (QD-LEDs) interesting for the next generation of display and lighting technologies. However, there still remain various hurdles to the commercialization of QD-LEDs, including their relatively low external quantum efficiencies (EQE). In this thesis, we study the efficiency loss mechanisms present in

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13

Puttaswamy, Gowda Yashvanth Basaralu. "Engineering Efficiency Droop in InGaN/GaN Multiple Quantum Well LEDs." OpenSIUC, 2012. https://opensiuc.lib.siu.edu/theses/810.

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In this work, we propose a model to address the challenge of droop in internal quantum efficiency in InGaN/GaN Multiple Quantum Well LEDs. Efficiency droop limits the performance of high brightness LEDs as they operate at currents greater than 350mA. The efficiency droop is a multi-physics problem posed by various entities such as (1) dislocation recombination, (2) Auger recombination in active region, (3) non-radiative recombination, and (4) current overflow in the active region. This work aims at reducing the droop associated with non-radiative recombination by engineering the quantum well b

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Patalay, Dinkar. "64-bit high efficiency binary comparator in quantum-dot cellular automata." Thesis, California State University, Long Beach, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10111200.

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<p> Quantum-dot Cellular Automata (QCA) are proposed models of quantum computation, which are articulated in analogy to Von Neumann's conventional models of cellular automata. These models are worthy for the architecture of ultra-dense low-power and high-performance digital circuits. Efficient solutions have recently been proposed for several arithmetic circuits, such as adders, multipliers, and comparators. Since the design of digital circuits in QCA still poses several challenges, novel implementation strategies and methodologies are highly desirable. This project demonstrates a new design

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15

Wilson, Brent R. "Accuracy and Efficiency in Computational Chemistry: The Correlation Consistent Composite Approach." Thesis, University of North Texas, 2011. https://digital.library.unt.edu/ark:/67531/metadc84300/.

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One of the central concerns of computational chemistry is that of efficiency (i.e. the development of methodologies which will yield increased accuracy of prediction without requiring additional computational resources – RAM, disk space, computing time). Though the equations of quantum mechanics are known, the solutions to these equations often require a great deal of computing power. This dissertation primarily concerns the theme of improved computational efficiency (i.e. the achievement of greater accuracy with reduced computational cost). Improvements in the efficiency of computational ch

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Rasin, Ahmed Tasnim. "High efficiency quantum dot-sensitised solar cells by material science and device architecture." Thesis, Queensland University of Technology, 2014. https://eprints.qut.edu.au/78822/1/Ahmed%20Tasnim_Rasin_Thesis.pdf.

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This thesis studied cadmium sulfide and cadmium selenide quantum dots and their performance as light absorbers in quantum dot-sensitised solar cells. This research has made contributions to the understanding of size dependent photodegradation, passivation and particle growth mechanism of cadmium sulfide quantum dots using SILAR method and the role of ZnSe shell coatings on solar cell performance improvement.

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Århus, Åsne. "Wet-chemical deposition of silicon quantum dots for enhanced solar cell efficiency." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for materialteknologi, 2011. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-16318.

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Silicon quantum dots were synthesised wet-chemically by three different methods based on reduction of silicon tetrachloride with the reduction agents potassium naphthalide, sodium cyclopentadiene and the alkalide of potassium. The purpose of these quantum dots was to deposit them on a substrate in order to use them as down converters on top of photovoltaic solar cells for enhanced solar cell efficiency. One possible method for the formation of down converting layers is to incorporate quantum dots into silica thin films by deposition of quantum dots in an ethanol based silica sol, followed by s

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Ford, J. S. "Applied molecular quantum electrodynamics : geometric aspects of the efficiency of photonic interactions." Thesis, University of East Anglia, 2015. https://ueaeprints.uea.ac.uk/59366/.

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This thesis presents applications of molecular quantum electrodynamics (MQED) to the analysis of resonance energy transfer (RET), molecular absorption and emission, and light scattering by molecules. An MQED framework describes such processes as a series of microscopic photonic interaction events. Multi-interaction processes entail intermediate states of the system’s evolution remaining unspecified, requiring careful interpretation. RET, as modified by coupling with the nearest molecule of the surrounding refractive medium, is investigated. Special attention is given to a system geometry where

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Li, Ying. "Fluorescence quantum efficiency determination of potential laser materials using a photocalorimetric technique." Thesis, Queen's University Belfast, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.334570.

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Hoffmann, Eric A. 1982. "The thermoelectric efficiency of quantum dots in indium arsenide/indium phosphide nanowires." Thesis, University of Oregon, 2009. http://hdl.handle.net/1794/10552.

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xi, 193 p. : ill. (some col.) A print copy of this thesis is available through the UO Libraries. Search the library catalog for the location and call number.<br>State of the art semiconductor materials engineering provides the possibility to fabricate devices on the lower end of the mesoscopic scale and confine only a handful of electrons to a region of space. When the thermal energy is reduced below the energetic quantum level spacing, the confined electrons assume energy levels akin to the core-shell structure of natural atoms. Such "artificial atoms", also known as quantum dots, can be lo

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21

Osorio, Carlos Ivan Henao. "Robustness against noise and efficiency of two-way quantum key distribution protocols." reponame:Repositório Institucional da UFABC, 2014.

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Orientador: Prof. Dr Carlos Ivan Henao Osorio<br>Dissertação (mestrado) - Universidade Federal do ABC, Programa de Pós-Graduação em Física, 2014.<br>Neste trabalho, apresentamos novos resultados sobre segurança de protocolos de distribuição quântica de chave de duas vías (TWQKD por suas iniciáis em inglês) que utilizam estados não ortogonáis. Trabalhamos no cenário de protocolos para os quais o pós-processamento é feito com comunicação clássica de uma via e não há pre-processamento. O análise de segurança é implementado com tecnicas que permitem cubrir conjuntos de protocolos bastante amplos.

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Cheriton, Ross. "Design and Characterization of InGaN/GaN Dot-in-Nanowire Heterostructures for High Efficiency Solar Cells." Thesis, Université d'Ottawa / University of Ottawa, 2018. http://hdl.handle.net/10393/37905.

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Light from the sun is an attractive source of energy for its renewability, supply, scalability, and cost. Silicon solar cells are the dominant technology of choice for harnessing solar energy in the form of electricity, but the designs are approaching their practical efficiency limits. New multijunction designs which use the tunable properties of the more expensive III-V semiconductors have historically been relegated to space applications where absolute power conversion efficiency, resilience to radiation, and weight are more important considerations than cost. Some of the more recent develop

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23

Massabuau, Fabien Charles-Paul. "The impact of the nanostructure of InGaN/GaN quantum wells on LED efficiency." Thesis, University of Cambridge, 2015. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.708520.

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Kamiya, Norikazu. "Classical Reduction of Quantum Master Equations as Similarity Transformation." 京都大学 (Kyoto University), 2015. http://hdl.handle.net/2433/199085.

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Anishchenko, Anastasiia [Verfasser], and Oliver [Akademischer Betreuer] Mülken. "Efficiency of continuous-time quantum walks: from networks with disorder to deterministic fractals." Freiburg : Universität, 2015. http://d-nb.info/1122592876/34.

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26

Lu, Kyle Benjamin. "Microwave Instrumentation and Sensing Techniques for Quantum Efficiency and Minority-Carrier Lifetime Measurements." PDXScholar, 2017. https://pdxscholar.library.pdx.edu/open_access_etds/3503.

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A non-contact method characterizing the quantum efficiency of a solar cell using the microwave reflectance signature is presented in this thesis. Traditional solar cell quantum efficiency (QE) measurements are only possible near the completion of the fabrication process using contacts in direct physical connection with the metalized surface tabs to probe and extract charge carriers from the device. However, pressure within the solar metrology industry to report the spectral performance of the device earlier in the manufacturing process as part of the process control loop requires that a new no

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Tabor, Steven Alan. "Spectral and Spatial Quantum Efficiency of AlGaAs/GaAs and InGaAs/InP PIN Photodiodes." PDXScholar, 1991. https://pdxscholar.library.pdx.edu/open_access_etds/4760.

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This thesis reports a novel system capable of testing both the spectral responsivity and the spatial quantum efficiency uniformity of heterostructure photodiodes using optical fiber coupled radiation. Testing was performed to confirm device specifications. This study undertakes to quantify the spectral bandwidth of an AlGaAs I GaAs double heterostructure photodiode and two InGaAs I InP double heterostructure PIN photodiodes at D.C., through the use of spatial scanning. The spatial scanning was done using lasers at 670 nm, 780 nm, 848 nm, 1300 nm, and 1550 nm, coupled through singlemode optical

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Snyman, LW, H. Aharoni, and Plessis M. du. "A dependency of quantum efficiency of silicon CMOS n+pp+ LEDs on current density." IEEE Photonics Technology Letters, 2005. http://encore.tut.ac.za/iii/cpro/DigitalItemViewPage.external?sp=1001057.

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Abstract—A dependency of quantum efficiency of nn+pp+ silicon complementary metal–oxide–semiconductor integrated lightemitting devices on the current density through the active device areas is demonstrated. It was observed that an increase in current density from 1 6 10+2 to 2 2 10+4 A cm 2 through the active regions of silicon n+pp+ light-emitting diodes results in an increase in the external quantum efficiency from 1 6 10 7 to 5 8 10 6 (approximately two orders of magnitude). The light intensity correspondingly increase from 10 6 to 10 1 W cm 2 mA (approximately five orders of magnitude). In

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Davies, Matthew John. "Optical studies of InGaN/GaN quantum well structures." Thesis, University of Manchester, 2014. https://www.research.manchester.ac.uk/portal/en/theses/optical-studies-of-ingangan-quantum-well-structures(f6c6e59b-8366-44aa-b149-9338d3f03dc0).html.

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In this thesis I present and discuss the results of optical spectroscopy performed on InGaN/GaN single and multiple quantum well (QW) structures. I report on the optical properties of InGaN/GaN single and multiple QW structures, measured at high excitation power densities. I show a correlation exists between the reduction in PL efficiency at high excitation power densities, the phenomenon so-called ``efficiency-droop'', and a broadening of the PL spectra. I also show a distinct change in recombination dynamics, measured by time-resolved photoluminescence (PL), which occurs at the excitation po

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Ekins-Daukes, Nicholas John. "An investigation into the efficiency enhancement of strained and strain-balanced quantum well solar cells." Thesis, Imperial College London, 2000. http://hdl.handle.net/10044/1/8093.

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HU, CHENXI. "Simulation studies and design of AlInGaN-ZnSiGeN2 quantum wells for high-efficiency ultraviolet light emitters." The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1589300145090549.

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Zhang, Fan. "QUANTUM EFFICIENCY ENHANCEMENT FOR GAN BASED LIGHT-EMITTING DIODES AND VERTICAL CAVITY SURFACE-EMITTING LASERS." VCU Scholars Compass, 2014. http://scholarscompass.vcu.edu/etd/3655.

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This thesis explores the improvement of quantum efficiencies for InGaN/GaN heterostructures and their applications in light-emitting diodes (LEDs) and vertical cavity surface-emitting lasers (VCSELs). Different growth approaches and structural designs were investigated to identify and address the major factors limiting the efficiency. (1) Hot electron overflow and asymmetrical electron/hole injection were found to be the dominant reasons for efficiency degradation in nitride LEDs at high injection; (2) delta p-doped InGaN quantum barriers were employed to improve hole concentration inside th

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Chanlek, Narong. "Quantum efficiency lifetime studies using the photocathode preparation experimental facility developed for the ALICE Accelerator." Thesis, University of Manchester, 2012. https://www.research.manchester.ac.uk/portal/en/theses/quantum-efficiency-lifetime-studies-using-the-photocathode-preparation-experimental-facility-developed-for-the-alice-accelerator(197791f0-518e-4257-aa0e-04f9942b4110).html.

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This thesis describes the development of a gallium arsenide (GaAs) photocathode preparation facility (PPF) with a load-lock interface as part of an upgrade to the ALICE photo-injector electron gun. The PPF has the capacity to prepare up to six negative electron affinity (NEA) GaAs photocathodes, and permits the rapid and reliable replacement of the degraded photocathode in the gun, while maintaining the integrity of the gun vacuum system. The photocathode preparation has been studied and developed using a custum-built surface characterisation system which permitsthe preparation of NEA GaAs pho

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Dajczgewand, Julian. "Optical memory in an erbium doped crystal : efficiency, bandwidth and noise studies for quantum memory applications." Thesis, Université Paris-Saclay (ComUE), 2015. http://www.theses.fr/2015SACLS198/document.

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Le traitement quantique de l’information comme moyen de surmonter les limites de l’électronique classique a connu un développement rapide dans les deux dernières décennies. Plusieurs composants pour générer, traiter et envoyer l’information quantique sont nécessaires. Dans ce contexte, les mémoires quantiques optiques apparaissent comme des composantes principales capables de communiquer l’information quantique sur de longues distances en surmontant les pertes des fibres optiques dans un schéma de répéteur quantique. Durant la dernière décennie, plusieurs protocoles de stockage pour stocker l’

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WANG, WEN-CHUN, and 王文駿. "Photoconductivities in SnO2 nanowires: Photoconduction Efficiency and Quantum Efficiency." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/51014177860346944648.

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碩士<br>國立臺灣科技大學<br>電子工程系<br>101<br>In this thesis, We report on the superior photoconduction (PC) efficiency and the dynamic study of the wide-bandgap single-crystalline tin dioxide (SnO2) nanowires (NWs). The photoconductive gain of the single-wire device can go up to 8x10^8 at a low bias of 3.0 V, which is the highest reported value to date for the single nanostructure photodetectors. Especially, the optimal normalized gain with the physical meaning of intrinsic PC efficiency of SnO2 NWs reaches 20 cm^2/V, which is over one to five orders of magnitude higher than the other highly efficient me

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Lee, Kuo-Chang, and 李國彰. "High Qubit Efficiency Quantum Key Distributions." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/13469574998704329480.

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博士<br>國立成功大學<br>資訊工程學系碩博士班<br>97<br>The security of key distribution in the classical cryptography is usually based on the fact that an attacker is unable to solve a certain mathematical problem, such as the discrete logarithm problem or the factoring problem. In the environment of quantum computation, the discrete logarithm problem and the factoring problem have been found solvable in the polynomial time. More classical mathematical problems may become insecure against the quantum computation in the future. Without using the mathematical problem, the quantum key distribution provides the unco

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Lin, Szu-Min, and 林思閩. "2-Dimensional Quantum Effect on Quantum Efficiency of Internal Photoemission Devices." Thesis, 1994. http://ndltd.ncl.edu.tw/handle/98458217701626012728.

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博士<br>國立清華大學<br>材料科學(工程)研究所<br>83<br>Internal photoemission infrared detectors have been widely used, such as PtSi/p-Si for the 3-5 um range, IrSi /p-Si for the 8-12 um range, as well as p+-SiGe/p-Si for 8-12 um range. Many models based on 3-dimensional concepts have been applied to explainning the transportation behavior of photoexcited carriers and characteristics of quantum efficiency. However, the thicknesses of the active layers of Schottky-barrier infrared photodiodes are in the orde

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Hou, Zou-Ying, and 侯志穎. "Effects of the profile of quantum well potentials on quantum engine efficiency." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/kp6kh4.

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碩士<br>國立東華大學<br>物理學系<br>105<br>This thesis studies the effects of perturbing the potential energy, which confines a quantum particle, on the efficiency of the quantum engine. The perturbations include the harmonic trap potential and the potential barrier that respectively are superimposed on the infinite potential well. Using quantum mechanics perturbation theory, the corresponding energy eigenstates with its eigenenergy of the particle are obtained. The efficiency of the quantum engine constructed from the ground state and the first excited state is analyzed. We find that the quantum engine b

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Wu, Kun-Cheng, and 吳崑誠. "Quantum Efficiency Measurement of Multi-Junction Solar Cell." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/80338720941960067925.

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碩士<br>國立彰化師範大學<br>電子工程學系<br>99<br>This thesis is aimed at studying the measurement principle of quantum efficiency for multi-junction solar cells and establishing a functional measurement system by integrating individual instruments. We measure GaAs multi-junction solar cells and then correlate the electrical characteristics with quantum efficiency of each epitaxial solar cell. We have been able to extract approximate quantum efficiency by using the theory and procedures presented in this thesis. However, due to some uncertain material parameters, the measurement parameters need to be fine tun

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"Quantum Efficiency Measurement of Nanowires Using Integrating Sphere." Master's thesis, 2012. http://hdl.handle.net/2286/R.I.14704.

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abstract: This thesis mainly focuses on the study of quantum efficiency (QE) and its measurement, especially for nanowires (NWs). First, a brief introduction of nano-technology and nanowire is given to describe my initial research interest. Next various fundamental kinds of recombination mechanisms are described; both for radiative and non-radiative processes. This is an introduction for defining the internal quantum efficiency (IQE). A relative IQE measurement method is shown following that. Then it comes to the major part of the thesis discussing a procedure of quantum efficiency measurement

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Yao, Liang-Yu, and 姚良雨. "Study on external quantum efficiency of AlGaInP LEDs." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/23779035181382773322.

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碩士<br>國立中興大學<br>精密工程研究所<br>93<br>In the study, the surface of AlGaInP light emitting diodes were roughened by dry and wet etching methods. Textured surface can increase the emitting area and allow more lights to escape from the surface of LEDs. It will enhance the light intensity and output power. In the dry etching process, polystyrene spheres were used to as natural mask. Polystyrene spheres were coated on the surface of AlGaInP LEDs in a randomly close-packed array. The surface of LEDs was roughened by ICP employing the mixture of Cl2 and Ar gases. After roughing, the light intensity and th

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XU, JIONG-SHENG, and 徐炯升. "High quantum efficiency narrow band self-filtering detectors." Thesis, 1990. http://ndltd.ncl.edu.tw/handle/68679957056780633809.

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Chen, Chih-Hao, and 陳之皓. "Suppression of Efficiency Droop and Improvement of Quantum Efficiency in Green Light Emitting Diodes using the Gradual InGaN Quantum Wells Structure." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/30314588759661593022.

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碩士<br>國立臺灣師範大學<br>光電科技研究所<br>98<br>The effect of gradual indium gallium nitride (InGaN) quantum wells (QWs) on the suppression of efficiency-droop in green light-emitting diodes (LEDs) is numerically investigated. The presented scheme increases the internal quantum efficiency (IQE) by 45.5% at I=20mA and 55.7% at I=100mA, indicating a considerable reduction of efficiency-droop. This improvement is attributable mainly to the use of the gradual InGaN QWs structure that significantly alleviates band bending in the valence band, improving the transport efficiency of injected holes above that of co

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May-Jaue, Huang, and 黃美嬌. "Improved external quantum efficiency and increase light-extraction efficiency of GaN Light-Emitting Diodes." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/26489271103271196162.

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碩士<br>國防大學中正理工學院<br>電子工程研究所<br>93<br>ABSTRACT The quantum efficiency of GaN-base light - emitting diodes (LED) has been significantly improved with the development of relative semiconductor epitaxy and process technology recently. However, the luminescence efficiency of LEDs is still not good due to the reasons of poor current-spreading, abrupt refractive index, and high defect density…etc. In this article, we report on the light-extraction and sulfide treatment of a blue GaN LED. In order to increase light-extraction efficiency from the GaN LEDs, we have used inductively coupled plasma (IC

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Tu, Chia-Cheng, and 杜佳政. "Study of Internal Quantum Efficiency and Efficiency Droop of GaN Based Near UV-LEDs." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/44aud9.

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碩士<br>中原大學<br>電子工程研究所<br>99<br>In this thesis, we focus on and improve the epitaxial structure of near-ultraviolet GaN-based light emitting diodes (LEDs), specifically in the internal quantum efficiency (IQE) and the droop effect at high current operation, respectively. In the first part, a novel grown method has been proposed by inserting the Si high-doped-layer (Si-HDL) between u-GaN and n-GaN layer through metal organic chemical vapor deposition (MOCVD). This method could greatly reduce defects density and improve the device performance due to the threading dislocations (TDs) from the u-G

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Chen, Kun-Cheng, and 陳坤成. "Conversion Efficiency Optimization on Broadband Quantum Dots Solar Cells." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/prpgxu.

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碩士<br>國立中山大學<br>光電工程學系研究所<br>101<br>III-V multi-junction solar cells (MJSC), which consist of different energy bandgap materials to match the solar spectrum, have been used in high concentrated photovoltaic (HCPV) to achieve high solar power conversion efficiency (η). Self-assembled InGaAs quantum dots (QDs) structure is expected to be a good candidate for solar cells capable of absorbing light near 1.0 eV. Furthermore, the energy bandgaps for the QDs can be tuned by changing the material compositions and the dot size. By stacking these QD layers of different energy bandgaps, the optical absor

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Yang, Chiao-Chih, and 楊喬智. "Improvement in external quantum efficiency of GaN-based LEDs." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/54443675258936458496.

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碩士<br>國立中興大學<br>精密工程研究所<br>93<br>In this thesis, we use surface-textured to increase light extraction to improve the external quantum efficiency of GaN-based LEDs . There is a significant gap between the internal and external efficiencies of conventional GaN light-emitting diodes (LEDs). The reason for this shortfall is the narrow escape cone for light in high refractive index GaN (n~2.5) to the air (n~1). In this paper, we choose five transparent film (ITO, SiO2, Polyimide, Photoresist 1, Photoresist 2) as the ITO/GaN LEDs widow layers and etching layers. Then we drop polystyrene spheres (PS)

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Chung, Yi-Heng, and 鍾易亨. "Improvement on External Quantum Efficiency of AlGaInP-Based LEDs." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/66311915588117177029.

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碩士<br>國立成功大學<br>微電子工程研究所碩博士班<br>91<br>Recently, with the quick development technique of metal organic chemical vapor deposition (MOCVD), the internal quantum efficiency of AlGaInP light emitting diodes (LEDs) can achieve near 100%. However, there is still a lot of hard work needed to improve the external quantum efficiency. The main purpose of this thesis is to improve external quantum efficiency of LEDs by investigating several different fabrication methods, which can help increase the brightness of LEDs. The first method proposed is the application of current blocking layer to LED struct

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Cheng-HsuehLu and 呂政學. "Improvement of internal quantum efficiency for InGaN/GaN multiple quantum wells based light-emitting diodes." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/aj6c5u.

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博士<br>國立成功大學<br>材料科學及工程學系<br>102<br>This research is focused on light emission efficiency enhancement of InGaN/GaN multiple quantum wells (MQWs) based blue or green light-emitting diodes (LEDs), which were grown by metalorganic chemical vapor deposition (MOCVD). With respect to the major manufacturing procedures of the LEDs from epitaxial growth of MQWs, wafer fabrication to chip fabrication, the corresponding methods are proposed and demonstrated to improve internal quantum efficiency (IQE) for better lighting performance. The main techniques and concepts include (1) fabrication of high-densi

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Maria, Ahmed. "Improving the photoluminescence quantum efficiency of size-tunable, solution-processed lead-sulfide quantum dots in film." 2004. http://link.library.utoronto.ca/eir/EIRdetail.cfm?Resources__ID=95027&T=F.

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