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Ultrafast Electron Diffraction for the Dynamical Study of 2D Materials
- A. A. Petruk, Nicolas Rivas, T. Dekker, K. Pichugin, A. W. Tsen, G. Sciaini
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- Journal:
- Microscopy and Microanalysis / Volume 24 / Issue S1 / August 2018
- Published online by Cambridge University Press:
- 01 August 2018, pp. 1598-1599
- Print publication:
- August 2018
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- Article
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- By Victoria M. Allen, Frederic Amant, Sarah Armstrong, Thomas F. Baskett, Michael A. Belfort, Meredith Birsner, Renee D. Boss, Leanne Bricker, Josaphat K. Byamugisha, Giorgio Capogna, Michael P. Casaer, Frank A. Chervenak, Vicki Clark, Filip Claus, Malachy O. Columb, Charles Cox, Jean T. Cox, Vegard Dahl, John Davison, Jan Deprest, Clifford S. Deutschman, Roland Devlieger, Karim Djekidel, Steven Dymarkowski, Roshan Fernando, Clare Fitzpatrick, Sreedhar Gaddipati, Thierry Girard, Emily Gordon, Ian A. Greer, David Grooms, Sina Haeri, Katy Harrison, Edward J. Hayes, Michelle Hladunewich, Andra H. James, Tracey Johnston, Bellal Joseph, Erin Keely, Ruth Landau, Stephen E. Lapinsky, Susanna I. Lee, Larry Leeman, Hennie Lombaard, Stephen Lu, Alison MacArthur, Laura A. Magee, Paul E. Marik, Laurence B. McCullough, Alexandre Mignon, Carlo Missant, Jack Moodley, Lisa E. Moore, Kate Morse, Warwick D. Ngan Kee, Catherine Nelson-Piercy, Clemens M. Ortner, Geraldine O’Sullivan, Luis D. Pacheco, Fathima Paruk, Melina Pectasides, Nigel Pereira, Patricia Peticca, Sharon T. Phelan, Felicity Plaat, Lauren A. Plante, Michael P. Plevyak, Dianne Plews, Wendy Pollock, Laura C. Price, Peter Rhee, Leiv Arne Rosseland, Kathryn M. Rowan, Helen Ryan, Helen Scholefield, Neil S. Seligman, Nadir Sharawi, Alex Sia, Bob Silver, Mieke Soens, Ulrich J. Spreng, Silvia Stirparo, Nova Szoka, Andrew Tang, Kha M. Tran, Els Troost, Lawrence C. Tsen, Derek Tuffnell, Kristel Van Calsteren, Marc Van de Velde, Marcel Vercauteren, Chris Verslype, Peter von Dadelszen, Carl Waldman, Michelle Walters, Linda Watkins, Paul Westhead, Cynthia A. Wong, Gerda G. Zeeman, Joost J. Zwart
- Edited by Marc van de Velde, Helen Scholefield, Lauren A. Plante
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- Book:
- Maternal Critical Care
- Published online:
- 05 July 2013
- Print publication:
- 04 July 2013, pp ix-xiv
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- By Aakash Agarwala, Linda S. Aglio, Rae M. Allain, Paul D. Allen, Houman Amirfarzan, Yasodananda Kumar Areti, Amit Asopa, Edwin G. Avery, Patricia R. Bachiller, Angela M. Bader, Rana Badr, Sibinka Bajic, David J. Baker, Sheila R. Barnett, Rena Beckerly, Lorenzo Berra, Walter Bethune, Sascha S. Beutler, Tarun Bhalla, Edward A. Bittner, Jonathan D. Bloom, Alina V. Bodas, Lina M. Bolanos-Diaz, Ruma R. Bose, Jan Boublik, John P. Broadnax, Jason C. Brookman, Meredith R. Brooks, Roland Brusseau, Ethan O. Bryson, Linda A. Bulich, Kenji Butterfield, William R. Camann, Denise M. Chan, Theresa S. Chang, Jonathan E. Charnin, Mark Chrostowski, Fred Cobey, Adam B. Collins, Mercedes A. Concepcion, Christopher W. Connor, Bronwyn Cooper, Jeffrey B. Cooper, Martha Cordoba-Amorocho, Stephen B. Corn, Darin J. Correll, Gregory J. Crosby, Lisa J. Crossley, Deborah J. Culley, Tomas Cvrk, Michael N. D'Ambra, Michael Decker, Daniel F. Dedrick, Mark Dershwitz, Francis X. Dillon, Pradeep Dinakar, Alimorad G. Djalali, D. John Doyle, Lambertus Drop, Ian F. Dunn, Theodore E. Dushane, Sunil Eappen, Thomas Edrich, Jesse M. Ehrenfeld, Jason M. Erlich, Lucinda L. Everett, Elliott S. Farber, Khaldoun Faris, Eddy M. Feliz, Massimo Ferrigno, Richard S. Field, Michael G. Fitzsimons, Hugh L. Flanagan Jr., Vladimir Formanek, Amanda A. Fox, John A. Fox, Gyorgy Frendl, Tanja S. Frey, Samuel M. Galvagno Jr., Edward R. Garcia, Jonathan D. Gates, Cosmin Gauran, Brian J. Gelfand, Simon Gelman, Alexander C. Gerhart, Peter Gerner, Omid Ghalambor, Christopher J. Gilligan, Christian D. Gonzalez, Noah E. Gordon, William B. Gormley, Thomas J. Graetz, Wendy L. Gross, Amit Gupta, James P. Hardy, Seetharaman Hariharan, Miriam Harnett, Philip M. Hartigan, Joaquim M. Havens, Bishr Haydar, Stephen O. Heard, James L. Helstrom, David L. Hepner, McCallum R. Hoyt, Robert N. Jamison, Karinne Jervis, Stephanie B. Jones, Swaminathan Karthik, Richard M. Kaufman, Shubjeet Kaur, Lee A. Kearse Jr., John C. Keel, Scott D. Kelley, Albert H. Kim, Amy L. Kim, Grace Y. Kim, Robert J. Klickovich, Robert M. Knapp, Bhavani S. Kodali, Rahul Koka, Alina Lazar, Laura H. Leduc, Stanley Leeson, Lisa R. Leffert, Scott A. LeGrand, Patricio Leyton, J. Lance Lichtor, John Lin, Alvaro A. Macias, Karan Madan, Sohail K. Mahboobi, Devi Mahendran, Christine Mai, Sayeed Malek, S. Rao Mallampati, Thomas J. Mancuso, Ramon Martin, Matthew C. Martinez, J. A. Jeevendra Martyn, Kai Matthes, Tommaso Mauri, Mary Ellen McCann, Shannon S. McKenna, Dennis J. McNicholl, Abdel-Kader Mehio, Thor C. Milland, Tonya L. K. Miller, John D. Mitchell, K. Annette Mizuguchi, Naila Moghul, David R. Moss, Ross J. Musumeci, Naveen Nathan, Ju-Mei Ng, Liem C. Nguyen, Ervant Nishanian, Martina Nowak, Ala Nozari, Michael Nurok, Arti Ori, Rafael A. Ortega, Amy J. Ortman, David Oxman, Arvind Palanisamy, Carlo Pancaro, Lisbeth Lopez Pappas, Benjamin Parish, Samuel Park, Deborah S. Pederson, Beverly K. Philip, James H. Philip, Silvia Pivi, Stephen D. Pratt, Douglas E. Raines, Stephen L. Ratcliff, James P. Rathmell, J. Taylor Reed, Elizabeth M. Rickerson, Selwyn O. Rogers Jr., Thomas M. Romanelli, William H. Rosenblatt, Carl E. Rosow, Edgar L. Ross, J. Victor Ryckman, Mônica M. Sá Rêgo, Nicholas Sadovnikoff, Warren S. Sandberg, Annette Y. Schure, B. Scott Segal, Navil F. Sethna, Swapneel K. Shah, Shaheen F. Shaikh, Fred E. Shapiro, Torin D. Shear, Prem S. Shekar, Stanton K. Shernan, Naomi Shimizu, Douglas C. Shook, Kamal K. Sikka, Pankaj K. Sikka, David A. Silver, Jeffrey H. Silverstein, Emily A. Singer, Ken Solt, Spiro G. Spanakis, Wolfgang Steudel, Matthias Stopfkuchen-Evans, Michael P. Storey, Gary R. Strichartz, Balachundhar Subramaniam, Wariya Sukhupragarn, John Summers, Shine Sun, Eswar Sundar, Sugantha Sundar, Neelakantan Sunder, Faraz Syed, Usha B. Tedrow, Nelson L. Thaemert, George P. Topulos, Lawrence C. Tsen, Richard D. Urman, Charles A. Vacanti, Francis X. Vacanti, Joshua C. Vacanti, Assia Valovska, Ivan T. Valovski, Mary Ann Vann, Susan Vassallo, Anasuya Vasudevan, Kamen V. Vlassakov, Gian Paolo Volpato, Essi M. Vulli, J. Matthias Walz, Jingping Wang, James F. Watkins, Maxwell Weinmann, Sharon L. Wetherall, Mallory Williams, Sarah H. Wiser, Zhiling Xiong, Warren M. Zapol, Jie Zhou
- Edited by Charles Vacanti, Scott Segal, Pankaj Sikka, Richard Urman
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- Book:
- Essential Clinical Anesthesia
- Published online:
- 05 January 2012
- Print publication:
- 11 July 2011, pp xv-xxviii
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Analysis of Electron Transport in a High-Mobility Freestanding GaN Substrate Grown by Hydride Vapor-Phase Epitaxy
- F. Yun, H. Morkoc, D. L. Rode, K. T. Tsen, L. Farina, C. Kurdak, S. S. Park, K. Y. Lee
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- Journal:
- MRS Online Proceedings Library Archive / Volume 680 / 2001
- Published online by Cambridge University Press:
- 21 March 2011, E2.2
- Print publication:
- 2001
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Semiconductor nitrides grown on substrates with a large lattice mismatch typically contain extended and point defects that prevent the full potential of this material system from being attained. Among allthe substrate options explored so far, freestanding GaN templates appear ideal for homoepitaxial growth of GaN films. To this end, hydride vapor-phase epitaxial (HVPE) grown GaN templates with a thickness of more than 200 μm were thermally lifted off from the sapphire substrate and mechanically polished. The defect densityof such a template is expected to be non-uniform in the growth direction, especially near the back surface which was in close vicinity of the sapphire substrate. We, therefore, studied the transport properties of this template before and after the removal of a 30 μm region from the back-side. For as-prepared GaN, Hall mobilities of 1100 cm2/V-s and 6800 cm2/V-s were obtained at 295 K and 50 K, respectively. A simultaneous fitting of mobility and carrier concentration was used to quantify the contribution ofdifferent scattering mechanisms. When the backside was etched by ∼30 μm, Hall mobilities improved to 1200 cm2/V-s at 295 K and 7385 cmsup2/V-s at 48 K, respectively. A numerical solution of the Boltzmann transport equation (BTE) that deals with the inelastic nature of electron scattering by polar optical mode was employed to determine the acceptor concentration. Raman spectroscopy was employed to obtain LO and TO phonon energies, which were then used in the above-mentioned calculations. The best fittings of the mobility and carrier concentration data yield an average acceptor concentration of 4.9×1015 cm-3 and a donor concentration of 2.1×1016 cm-3 for the as-prepared GaN. The average acceptor concentration decreased to 2.4×1015 cm-3 after etching of the backside, which confirms that the etched-away region contained higher density of defects. The donor activation energy is derived to be 25.2 meV. Our analysis demonstrated high quality of the freestanding GaN substrate with the highest reported electron mobility for wurtzite GaN.
Subpicosecond Time-Resolved Raman Studies of Nonequilibrium Excitations in Wurtzite GaN
- K. T. Tsen, R. P. Joshi, D. K. Ferry, A. Botchkarev, B. Sverdlov, A. Salvador, H. Morkoc
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- Journal:
- MRS Online Proceedings Library Archive / Volume 449 / 1996
- Published online by Cambridge University Press:
- 10 February 2011, 737
- Print publication:
- 1996
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Non-equilibrium electron distributions as well as phonon dynamics in wurtzite GaN have been measured by subpicosecond time-resolved Raman spectroscopy. Our experimental results have demonstrated that for electron densities n ≥ 5 × l017cm−3, the non-equilibrium electron distributions in wurtzite GaN can be very well described by Fermi-Dirac distribution functions with the temperature of electrons substantially higher than that of the lattice. The population relaxation time of longitudinal optical phonons was directly measured to be τ ≅ 5 ± 1 ps at T = 25 K. The experimental results on the temperature dependence of the lifetime of longitudinal optical phonons suggest that the primary decay channels for these phonons are the decay into (1) one transverse optical phonon and one high energy, longitudinal or transverse acoustical phonons; and (2) one transverse optical phonon and one E2 phonon.