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93 results on '"Reed, Meredith"'

1. Exploring Preservice Teachers' Metaphor Plotlines

Author

Pinnegar, Stefinee, Mangelson, Jessica, and Reed, Meredith

Abstract

This study explores how entering female preservice teachers position themselves-the plotlines, obligations, responsibilities and duties they are prepared to enact, the expectations they hold for students, and the implications these have for teacher education. Using positioning theory, the authors analyze application letters of 20 elementary preservice teachers to uncover metaphor plotlines for teaching. Preservice teachers' application letters contained 12 metaphor plotlines presented here in terms of the definition, the role of teacher and the role of student. The paper explores implications for the content of teacher education, development as a teacher, and the ability to engage students. (Contains 1 table.)

Published
2011
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3. Into Teachers' Hands: Creating Classroom Success. The SDE Sourcebook. 11th Edition.

Author

Society for Developmental Education, Peterborough, NH., Reed, Meredith, Reed, Meredith, and Society for Developmental Education, Peterborough, NH.

Abstract

This compilation of resource materials includes article and book chapter reprints, checklists, and other materials of potential interest to early childhood and elementary school teachers. The book's seven sections are: (1) "Issues"; (2) "Multiyear Education"; (3) "Early Childhood"; (4) "Upper Elementary"; (5) "Assessment"; (6) "For Further Thought"; and (7) "Resources/Bibliography." This final section includes a variety of resources, including a classified list of World Wide Web sites, advocacy organizations, publications and publishers, and a bibliography containing 346 items. (LPP)

Published
1998

7. (super 4)(super J)COCCH and (super 4)(super J)CCCCH as probes of exocyclic hydroxymethyl group conformation in saccharides

Author

Qingfeng Pan, Klepach, Thomas, Carmichael, Ian, Reed, Meredith, and Serianni, Anthony S.

Subjects
Nuclear magnetic resonance spectroscopy -- Usage, Methyl groups -- Chemical properties, Methyl groups -- Spectra, Carbohydrates -- Chemical properties, Carbohydrates -- Spectra, Conformational analysis, Biological sciences, Chemistry
Abstract

H NMR spectra of aldohexopyranosyl rings (super 13)C-enrichment reveal the presence of long-range (super 4)(super J)C1,H6R/S and (super 4)(super J)C3,H6R/S whose magnitudes depend mainly on the O5-C5-C6-O6 torsion angle. Their magnitudes and signs are established, and their dependencies on the geometry of C1-O5-C5-C6-H6R/S and C3-C4-C5-C6-H6R/S coupling pathways are determined.

Published
2005

8. PROGRESS IN HIGH EFFICIENCY UV LED RESEARCH FOR REAGENTLESS BIOAGENT DETECTION AND WATER PURIFICATION

Author

REED, MEREDITH L., primary, GARRETT, GREGORY A., additional, SAMPATH, ANAND V., additional, SHEN, PAUL H., additional, COLLINS, CHARLES J., additional, WRABACK, MICHAEL, additional, ZHANG, JIANPING, additional, HU, XUHONG, additional, DENG, JIANYU, additional, LUNEV, ALEX, additional, BILENKO, YURIY, additional, KATONA, THOMAS, additional, and GASKA, REMIS, additional

Published
2008
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17. AlGaN/SiC Heterojunction Ultraviolet Photodiodes

Author

Sampath, Anand V., primary, Chen, Yoajia, additional, Zhou, Q., additional, Enck, Ryan W., additional, Garrett, Gregory A., additional, Vanmil, Brenda L., additional, Chung, Roy B., additional, Reed, Meredith L., additional, Shen, H., additional, Campbell, Joe C., additional, and Wraback, Michael, additional

Published
2016
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23. Fiscal Year 2011 Director's Strategic Initiative Final Report Heterogeneous Device Architectures Incorporating Nitride Semiconductors for Enhanced Functionality of Optoelectronic Devices

Author

ARMY RESEARCH LAB ADELPHI MD SENSORS AND ELECTRON DEVICES DIRECTORATE, Sampath, Anand V, Reed, Meredith L, Gerhold, Michael, Wraback, Michael, ARMY RESEARCH LAB ADELPHI MD SENSORS AND ELECTRON DEVICES DIRECTORATE, Sampath, Anand V, Reed, Meredith L, Gerhold, Michael, and Wraback, Michael

Abstract

Heterogeneous devices combine dissimilar materials with complementary device functionalities to achieve new functionalities that may provide revolutionary advances in technology. In these novel devices the physics and engineering of the interface of the dissimilar materials plays a critical role and requires considerable research. While nitride semiconductors have had great success as materials for sources and detectors of electromagnetic radiation across the spectrum from the ultraviolet (UV) to terahertz, heterogeneous integration of these materials with others having different spontaneous polarization, different crystal structure or a new functionality hold promise for devices with improved performance. This report discusses research efforts on two representative examples, III-Nitride/silicon carbide (SiC) avalanche photodetectors and compositionally inhomogeneous indium gallium nitride (InGaN) terahertz sources. Specifically, we demonstrate the efficacy of using III-Nitride semiconductors to improve the quantum efficiency (QE) of a photodetector employing a SiC-based gain region over a wide spectral range from 240 to 365 nm by overcoming surface states and weak absorption that limit the QE of homogenous SiC-based photodetectors in the deep UV and near UV regions, respectively. Furthermore, we have observed enhanced terahertz generation due to large internal in-plane electric fields in heteroepitaxially grown semi-polar and nonpolar GaN thin films due to the presence of self-assembled zincblende inclusions in an otherwise wurtzite crystal structure., The original document contains color images.

Published
2014

24. Optical polarization switching in semipolar ð2021Þ InGaN multiple quantum wells induced by strain engineering.

Author

Chung, Roy B., Garrett, Gregory A., Enck, Ryan W., Sampath, Anand V., Wraback, Michael, and Reed, Meredith L.

Subjects
OPTICAL polarization, QUANTUM wells, INDIUM gallium nitride, PHOTOLUMINESCENCE, VALENCE bands
Abstract

Semipolar (2021) InGaN/AlGaN multiple quantum wells (MQWs) with a low In content (<0.05) were coherently grown on a partially relaxed AlxGa1-xN (0Al<0.4) layer. As XAl increased from 0.15 to 0.38, the degree of optical polarization measured by photoluminescence at 13K changed from 0.49 to -0.24, where (-) indicates the change in the dominant polarization direction from [1120] to [1014]. Regardless of XAl and thickness, no polarization switching was observed if AlxGa1-xN was fully strained to the GaN substrate. Band structure modeling based on the k·p method implies that the polarization switching is associated with strong valence band mixing induced by the one-dimensional strain relaxation in AlGaN, which leads to a significantly stronger compressive strain in MQWs along [1014] relative to [1120]. These results demonstrate that the optical polarization switching in semipolar MQWs can be controlled by engineering the strain state of the underlying layer. [ABSTRACT FROM AUTHOR]

Published
2017
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25. Exploiting the Negative Polarization Properties of Indium Gallium Nitride (InGaN)/Gallium Nitride (GaN) Heterostructures to Achieve Frequency Doubled Blue-green Lasers with Deep Ultraviolet (UV) (<250 nm) Emission

Author

ARMY RESEARCH LAB ADELPHI MD, Reed, Meredith, Readinger, Eric D., ARMY RESEARCH LAB ADELPHI MD, Reed, Meredith, and Readinger, Eric D.

Abstract

There is an Army need to develop deep ultraviolet (UV) semiconductor lasers that are compact with a low power budget for use in real-time reagentless biodetection and identification systems as well as water monitoring. Our approach is to develop a visible indium gallium nitride (InGaN) based laser that exploits the negative polarization charge at the heterointerface, which can then be frequency doubled into the deep UV. In the first year of this Director's Research Initiative (DRI), we have developed and tested single heterostructure (SH) n-InxGa1-xN/p-GaN ("p-down") light emitting diodes (LEDs) with 22% In composition and having a peak intensity at 485 nm (blue-green). Under 1% DC, the current injection peaks above 100 A/cm2, well beyond the current density, 10-25 A/cm2, at which conventional p-up, Ga-polar InGaN/GaN multiple quantum well (MQW) LEDs exhibit significant efficiency droop. The achievement of a blue-green LED with reduced efficiency droop at high current densities is a necessary step for achieving a blue-green laser that uses the benefits of the negative polarization charge., The original document contains color images.

Published
2010

26. Improved UV Nitride Light Emitting Diode With Engineered Spontaneous and Piezoelectric Charges

Author

ARMY RESEARCH LAB ADELPHI MD, Shen, Paul H., Reed, Meredith L., Readinger, Eric D., Wraback, Michael, ARMY RESEARCH LAB ADELPHI MD, Shen, Paul H., Reed, Meredith L., Readinger, Eric D., and Wraback, Michael

Abstract

Most III-V nitride light emitting diodes have an n-type down structure with Ga polarity. In such a device, the active layer is grown on top of the n-cladding layer and the p-type cladding layer is grown on top of the active layer. We have analyzed the band structure of such a device and found a reduced effective conduction band barrier due to the positive spontaneous and piezoelectric polarization charge, resulting in large electron overshoot and necessitating the introduction of the commonly employed electron blocking layer. On the other hand, the polarization charge at the corresponding interface for a p-type down device with Ga polarity is negative, resulting in a significant enhancement of the electron barrier and the existence of a 2D hole gas near the interface. These are beneficial to the performance of single heterojunction LEDs. We have fabricated and tested such a device with a peak efficiency above 100A/sq cm and only approx. 10% droop up to 500A/sq cm, which was achieved without the implementation of an AlGaN electron-blocking layer or a second hetero-interface., See also ADM002187. Proceedings of the Army Science Conference (26th) Held in Orlando, Florida on 1-4 December 2008, The original document contains color images.

Published
2008

27. Study of Temperature-Dependent Carrier Transport in a p-GaN/i-InGaN/n-GaN Solar Cell Heterostructure using Ultrafast Spectroscopy

Author

Connelly, Blair C., primary, Woodward, Nathaniel T., additional, Metcalfe, Grace D., additional, Rodak, Lee E., additional, Das, Naresh C., additional, Reed, Meredith L., additional, Sampath, Anand V., additional, Shen, Hongen, additional, Wraback, Michael, additional, Farrell, Robert M., additional, Iza, Michael, additional, Cruz, Samantha C., additional, Lang, Jordan R., additional, Young, Nathan G., additional, Terao, Yutaka, additional, Neufeld, Carl J., additional, Keller, Stacia, additional, Nakamura, Shuji, additional, DenBaars, Steven P., additional, Mishra, Umesh K., additional, and Speck, James S., additional

Published
2013
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30. Current-induced degradation of high performance deep ultraviolet light emitting diodes

Author

Moe, Craig G., primary, Reed, Meredith L., additional, Garrett, Gregory A., additional, Sampath, Anand V., additional, Alexander, Troy, additional, Shen, Hongen, additional, Wraback, Michael, additional, Bilenko, Yuriy, additional, Shatalov, Maxim, additional, Yang, Jinwei, additional, Sun, Wenhong, additional, Deng, Jianyu, additional, and Gaska, Remis, additional

Published
2010
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32. Degradation mechanisms beyond device self-heating in deep ultraviolet light emitting diodes

Author

Moe, Craig G., primary, Reed, Meredith L., additional, Garrett, Gregory A., additional, Metcalfe, Grace D., additional, Alexander, Troy, additional, Shen, Hongen, additional, Wraback, Michael, additional, Lunev, Alex, additional, Bilenko, Yuriy, additional, Hu, Xuhong, additional, Sattu, Ajay, additional, Deng, Jianyu, additional, Shatalov, Maxim, additional, and Gaska, Remis, additional

Published
2009
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34. Faculty continues Winter Term debate

Author

Reed, Meredith

Subjects
News, opinion and commentary, Sports and fitness
Abstract

Byline: Meredith Reed Nearly 30 members of the DePauw faculty debated potential changes to the current Winter Term model in an open forum yesterday afternoon. Proposed changes to Winter Term [...]

Published
2013

35. A look at DePauw's African American history

Author

Reed, Meredith

Subjects
African Americans, News, opinion and commentary, Sports and fitness
Abstract

Byline: Meredith Reed Swanky big band music played in Peeler Art Center room 203 on Friday evening as the 'More than Uncommon: an African American Experience' exhibit celebrated African American [...]

Published
2013

36. Peer education program on mental illness to begin next school year

Author

Reed, Meredith

Subjects
Mental disorders, Education, Mental health services, News, opinion and commentary, Sports and fitness
Abstract

Byline: Meredith Reed This semester, DePauw Counseling Services will be recruiting upperclassmen for a new Peer Education Program, which will start during the 2013-2014 academic school year. According to the [...]

Published
2013

37. Faculty discuss search for VPAA, new courses in March meeting

Author

Reed, Meredith

Subjects
News, opinion and commentary, Sports and fitness
Abstract

Byline: Meredith Reed With 20 faculty members missing, attendance was low at the monthly faculty meeting on Monday. 'Call a colleague?' Bridget Gourley, chair of faculty, quipped about the small [...]

Published
2013

41. Fabrication and Characterization of Ultraviolet Light Emitting Diodes with Nanometer Scale Compositionally Inhomogeneous Active Regions

Author

Sampath, Anand V., primary, Reed, Meredith, additional, Garrett, Gregory, additional, Readinger, Eric D., additional, Shen, P., additional, Wraback, Michael, additional, Chua, Christoper, additional, Johnson, Noble, additional, Usikov, Alexander, additional, Kovalenkov, Oleg, additional, Shapovalova, Lisa, additional, and Dimtriev, Vladimir, additional

Published
2007
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46. Investigation of Nucleation and Intermixing at Hetero-Interface in III-Nitride-4H-SiC Structures

Author

Wade, Ryan, Sampath, Anand V, Chung, Roy, Knorr, Daniel B, Garrett, Gregory A, and Reed, Meredith L

Abstract

III-Nitride/SiC heterostructure devices are a promising approach for improving the performance of SiC devices such as bipolar transistors and avalanche photodiodes. However, the performance of these devices should critically depend on the properties of the hetero-interface that will likely lie within an active region of the device and impact carrier transport. Importantly, intermixing at the hetero-interface can effect doping profiles in these structures as constituent atoms of each semiconductor act as a dopant in the other. In this paper we explore the impact of in situ substrate preparation and migration enhanced epitaxy (MEE) on the nucleation and impurity concentration of thin AlN films grown by plasma-assisted molecular beam epitaxy on 4H-SiC. The surface morphology of the samples were examined by atomic force microscopy and the composition of the films were studies by secondary ion mass spectroscopy (SIMS) and depth profiling x-ray photoemission spectroscopy (XPS). The MEE approach promotes the nucleation of AlN growth on SiC in a 2D mode while suppressing the migration of Al into SiC. Active N that leaks around the closed shutter during in-situ preparation prevents the nucleation of AlN in a 2D growth mode at lower substrate temperatures that is attributed to GaN island formation at the hetero-interface.

Published
2016

47. PROGRESS IN HIGH EFFICIENCY UV LED RESEARCH FOR REAGENTLESS BIOAGENT DETECTION AND WATER PURIFICATION.

Author

Reed, Meredith L., Garrett, Gregory A., Sampath, Anand V., Shen, Paul H., Collins, Charles J., Wraback, Michael, Jianping Zhang, Xuhong Hu, Jianyu Deng, Lunev, Alex, Yuriy Bilenko, Katona, Thomas, and Gaska, Remis

Subjects
*ULTRAVIOLET radiation, *WATER purification, *LIGHT emitting diodes, *SEMICONDUCTOR diodes, *ELECTROLUMINESCENT devices, *PHOTOLUMINESCENCE, *LUMINESCENCE, *SEMICONDUCTORS, *ELECTRONICS, *LIGHT sources
Abstract

We present material and device characterization of 280 nm semiconductor ultraviolet light emitting diodes. These devices exhibit low series resistance, wavelength stability with increasing current, and have a half-life in excess of 570hrs, depending upon the injection current. Time-resolved photoluminescence studies of these materials prior to fabrication have been correlated with the device performance. We also discuss the potential for use in water purification. [ABSTRACT FROM AUTHOR]

Published
2008
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49. Exploiting the Benefits of Negative Polarization in n-InGaN/p-GaN Single Heterostructure Light Emitting Diode with p-side Down

Author

Reed, Meredith, Shen, Paul, Wraback, Mike, Syrkin, Alexander, and Usikov, Alexander

Abstract

In this paper we demonstrate the electrical and optical effects of negative polarization charge at the n-InGaN/p-GaN interface on the performance of single heterostructure n-InGaN/p-GaN LEDs with p-side down. This negative polarization charge at the interface leads to a reduced barrier for hole injection from p-GaN to n-InGaN, with a hole accumulation layer forming within the InGaN near the n-InGaN/p-GaN interface. Electrons encounter a significant barrier for injection from the n-InGaN into p-GaN, compounded by the heterobarrier, making p-GaN behave like an effective electron blocking layer. We show that the combination of 2D hole-gas formation on the n-InGaN side of the hetero-interface and enhancement of the electron barrier to transport across this interface may reduce efficiency droop at high current density without the need for an AlGaN electron blocking layer.

Published
2008

50. Time-Resolved Photoluminescence of Wideband Gap Semiconductor Devices

Author

Garrett, Gregory, Reed, Meredith, Sampath, Anand V., and, Shen, and Wraback, Michael

Abstract

The use of optical gating by frequency downconversion to study UV optoelectronic devices provides information on carrier recombination dynamics with sub-picosecond resolution. Measurement of active LEDs undergoing current injection and measurement of stimulated emission from UV laser cavities is demonstrated.

Published
2007

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