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103 results on '"VanMil, Brenda"'

1. Improvement of Morphology and Free Carrier Mobility through Argon-Assisted Growth of Epitaxial Graphene on Silicon Carbide

Author

Tedesco, Joseph L., VanMil, Brenda L., Myers-Ward, Rachael L., Culbertson, James C., Jernigan, Glenn G., Campbell, Paul M., McCrate, Joseph M., Kitt, Stephen A., Eddy, Jr., Charles R., and Gaskill, D. Kurt

Subjects
Condensed Matter - Mesoscale and Nanoscale Physics, Condensed Matter - Materials Science
Abstract

Graphene was epitaxially grown on both the C- and Si-faces of 4H- and 6H-SiC(0001) under an argon atmosphere and under high vacuum conditions. Following growth, samples were imaged with Nomarski interference contrast and atomic force microscopies and it was found that growth under argon led to improved morphologies on the C-face films but the Si-face films were not significantly affected. Free carrier transport studies were conducted through Hall effect measurements, and carrier mobilities were found to increase and sheet carrier densities were found to decrease for those films grown under argon as compared to high vacuum conditions. The improved mobilities and concurrent decreases in sheet carrier densities suggest a decrease in scattering in the films grown under argon., Comment: 215th Meeting of the Electrochemical Society (ECS 215), 14 pages, 6 figures

Published
2009
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2. Hall Effect Mobility of Epitaxial Graphene Grown on Silicon Carbide

Author

Tedesco, Joseph L., VanMil, Brenda L., Myers-Ward, Rachael L., McCrate, Joseph M., Kitt, Stephen A., Campbell, Paul M., Jernigan, Glenn G., Culbertson, James C., Eddy, Jr., Charles R., and Gaskill, D. Kurt

Subjects
Condensed Matter - Mesoscale and Nanoscale Physics, Condensed Matter - Materials Science
Abstract

Epitaxial graphene films were grown in vacuo by silicon sublimation from the (0001) and (000-1) faces of 4H- and 6H-SiC. Hall effect mobilities and sheet carrier densities of the films were measured at 300 K and 77 K and the data depended on the growth face. About 40% of the samples exhibited holes as the dominant carrier, independent of face. Generally, mobilities increased with decreasing carrier density, independent of carrier type and substrate polytype. The contributions of scattering mechanisms to the conductivities of the films are discussed. The results suggest that for near-intrinsic carrier densities at 300 K epitaxial graphene mobilities will be ~150,000 cm2V-1s-1 on the (000-1) face and ~5,800 cm2V-1s-1 on the (0001) face., Comment: Accepted for publication in Applied Physics Letters, 10 pages, 2 figures

Published
2009
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3. Epitaxial Graphene Growth on SiC Wafers

Author

Gaskill, D. Kurt, Jernigan, Glenn G., Campbell, Paul M., Tedesco, Joseph L., Culbertson, James C., VanMil, Brenda L., Myers-Ward, Rachael L., Eddy, Jr., Charles R., Moon, Jeong, Curtis, D., Hu, M., Wong, D., McGuire, C., Robinson, Joshua A., Fanton, Mark A., Stitt, Joseph P., Stitt, Thomas, Snyder, David, Weng, Xiaojun, and Frantz, Eric

Subjects
Condensed Matter - Materials Science, Condensed Matter - Mesoscale and Nanoscale Physics
Abstract

An in vacuo thermal desorption process has been accomplished to form epitaxial graphene (EG) on 4H- and 6H-SiC substrates using a commercial chemical vapor deposition reactor. Correlation of growth conditions and the morphology and electrical properties of EG are described. Raman spectra of EG on Si-face samples were dominated by monolayer thickness. This approach was used to grow EG on 50 mm SiC wafers that were subsequently fabricated into field effect transistors with fmax of 14 GHz., Comment: 215th Meeting of the Electrochemical Society, 8 pages, 8 figures

Published
2009
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4. Graphene formation on SiC substrates

Author

VanMil, Brenda L., Myers-Ward, Rachael L., Tedesco, Joseph L., Eddy, Jr., Charles R., Jernigan, Glenn G., Culbertson, James C., Campbell, Paul M., McCrate, Joseph M., Kitt, Stephen A., and Gaskill, D. Kurt

Subjects
Condensed Matter - Materials Science, Condensed Matter - Mesoscale and Nanoscale Physics
Abstract

Graphene layers were created on both C and Si faces of semi-insulating, on-axis, 4H- and 6H-SiC substrates. The process was performed under high vacuum (<10-4 mbar) in a commercial chemical vapor deposition SiC reactor. A method for H2 etching the on-axis sub-strates was developed to produce surface steps with heights of 0.5 nm on the Si-face and 1.0 to 1.5 nm on the C-face for each polytype. A process was developed to form graphene on the substrates immediately after H2 etching and Raman spectroscopy of these samples confirmed the formation of graphene. The morphology of the graphene is described. For both faces, the underlying substrate morphology was significantly modified during graphene formation; sur-face steps were up to 15 nm high and the uniform step morphology was sometimes lost. Mo-bilities and sheet carrier concentrations derived from Hall Effect measurements on large area (16 mm square) and small area (2 and 10 um square) samples are presented and shown to compare favorably to recent reports., Comment: European Conference on Silicon Carbide and Related Materials 2008 (ECSCRM '08), 4 pages, 4 figures

Published
2009
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5. Correlating Raman Spectral Signatures with Carrier Mobility in Epitaxial Graphene: A Guide to Achieving High Mobility on the Wafer Scale

Author

Robinson, Joshua A., Wetherington, Maxwell, Tedesco, Joseph L., Campbell, Paul M., Weng, Xiaojun, Stitt, Joseph, Fanton, Mark A., Frantz, Eric, Snyder, David, VanMil, Brenda L., Jernigan, Glenn G., Myers-Ward, Rachael L., Eddy, Jr., Charles R., and Gaskill, D. Kurt

Subjects
Condensed Matter - Materials Science
Abstract

We report a direct correlation between carrier mobility and Raman topography of epitaxial graphene (EG) grown on silicon carbide (SiC). We show the Hall mobility of material on the Si-face of SiC [SiC(0001)] is not only highly dependent on thickness uniformity but also on monolayer strain uniformity. Only when both thickness and strain are uniform over a significant fraction (> 40%) of the device active area does the mobility exceed 1000 cm2/V-s. Additionally, we achieve high mobility epitaxial graphene (18,100 cm2/V-s at room temperature) on the C-face of SiC [SiC(000-1)] and show that carrier mobility depends strongly on the graphene layer stacking. These findings provide a means to rapidly estimate carrier mobility and provide a guide to achieve very high mobility in epitaxial graphene. Our results suggest that ultra-high mobilities (>50,000 cm2/V-s) are achievable via the controlled formation of uniform, rotationally faulted epitaxial graphene., Comment: 13 pages including supplimental material. Submitted to Nature Materials 2/23/2009

Published
2009
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10. 4H-SiC Visible-blind single-photon avalanche diode for ultraviolet detection at 280 and 350 nm

Author

Jun Hu, Xiaobin Xin, Xueqing Li, Jian H. Zhao, VanMil, Brenda L., Kok-Keong Lew, Myers-Ward, Rachael L., Eddy, Charles R., Jr., and Gaskill, D. Kurt

Subjects
Photon detectors -- Evaluation, Silicon carbide -- Electric properties, Ultraviolet radiation -- Usage, Business, Electronics, Electronics and electrical industries
Abstract

A 4H-SiC single-photon avalanche diode (SPAD) operating at ultraviolet (UV) wavelengths of 280 and 350 nm is described. The combination of high single-photon detection efficiency (SPDE) and high photon count rate, low dark current rate (DCR) and low dark current have shown the emergence of the SiC SPAD as a powerful competitor in the area of UV single-photon detectors.

Published
2008

12. Near ultraviolet enhanced 4H-SiC Schottky diode

Author

Shen, Yang, primary, Jones, Andrew H., additional, Yuan, Yuan, additional, Zheng, Jiyuan, additional, Peng, Yiwei, additional, VanMil, Brenda, additional, Olver, Kimberley, additional, Sampath, Anand V., additional, Parker, Cory, additional, Opila, Elizabeth, additional, and Campbell, Joe C., additional

Published
2019
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13. Development toward Wafer-Scale Graphene RF Electronics

Author

Moon, Jeong, primary, Curtis, D, additional, Hu, M, additional, Wong, D, additional, Campbell, Paul, additional, Jernigan, Glenn, additional, Tedesco, Joseph L., additional, VanMil, Brenda, additional, Myers-Ward, R. L., additional, Eddy, Charles, additional, Gaskill, D. K., additional, Robinson, Joshua, additional, Fanton, Mark, additional, and Asbeck, P, additional

Published
2019
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15. Effect of polarity on the growth of InN films by metalorganic chemical vapor deposition.

Author

Jain, Abhishek, Weng, Xiaojun, Raghavan, Srinivasan, VanMil, Brenda L., Myers, Thomas, and Redwing, Joan M.

Subjects
ORGANOMETALLIC compounds, INDIUM, NITROGEN, CHEMICAL vapor deposition, DIFFRACTION patterns, SURFACE roughness, ELECTRON diffraction
Abstract

The effect of surface polarity on InN growth on GaN by metalorganic chemical vapor deposition (MOCVD) was investigated. The polarity of the InN was found to follow that of the initial GaN template as determined by a comparison of experimental and simulated convergent beam electron diffraction patterns. Under identical MOCVD growth conditions, In-polar InN was observed to nucleate and grow on Ga-polar GaN as pyramidal-shaped islands with [formula] as the stable surface facet. In contrast, enhanced lateral growth and reduced surface roughness were observed for N-polar InN grown on N-polar GaN. InN films grown on (0001) sapphire substrates using a thin AlN buffer under identical conditions to those used for growth on the GaN templates also exhibited reduced surface roughnesses and were determined to be N polar. A qualitative model based on the difference in surface terminations and crystal structures is proposed to explain the observed differences in the structural properties and growth modes of the In-polar and N-polar InN films. [ABSTRACT FROM AUTHOR]

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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18. Studies of spatial uniformity and jitter in SiC UV SPADs

Author

Itzler, Mark A., Bienfang, Joshua C., McIntosh, K. Alex, Sampath, Anand V., Garrett, Gregory A., Schuster, Jonathan, Smith, Jeremy L., Derenge, Michael A., Habersat, Daniel B., VanMil, Brenda, Gandhi, Reza, Dolinsky, Sergei, Heilweil, Edwin J., Bienfang, Joshua C., Bellotti, Enrico, and Wraback, Michael

Published
2023
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19. Mercury cadmium selenide for infrared detection

Author

Doyle, Kevin, primary, Swartz, Craig H., additional, Dinan, John H., additional, Myers, Thomas H., additional, Brill, Gregory, additional, Chen, Yuanping, additional, VanMil, Brenda L., additional, and Wijewarnasuriya, Priyalal, additional

Published
2013
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24. On the high curvature coefficient rectifying behavior of nanocrystalline diamond heterojunctions to 4H-SiC

Author

Tadjer, Marko J., primary, Feygelson, Tatyana I., additional, Hobart, Karl D., additional, Caldwell, Joshua D., additional, Anderson, Travis J., additional, Butler, James E., additional, Eddy, Charles R., additional, Gaskill, D. Kurt, additional, Lew, K. K., additional, VanMil, Brenda L., additional, Myers-Ward, Rachael L., additional, Kub, Fritz J., additional, Sollenberger, Gregory, additional, and Brillson, Leonard, additional

Published
2010
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28. Correlating Raman Spectral Signatures with Carrier Mobility in Epitaxial Graphene: A Guide to Achieving High Mobility on the Wafer Scale

Author

Robinson, Joshua A., primary, Wetherington, Maxwell, additional, Tedesco, Joseph L., additional, Campbell, Paul M., additional, Weng, Xiaojun, additional, Stitt, Joseph, additional, Fanton, Mark A., additional, Frantz, Eric, additional, Snyder, David, additional, VanMil, Brenda L., additional, Jernigan, Glenn G., additional, Myers-Ward, Rachael L., additional, Eddy, Charles R., additional, and Gaskill, D. Kurt, additional

Published
2009
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30. Epitaxial Graphene Growth on SiC Wafers

Author

Gaskill, D. K., primary, Jernigan, Glenn, additional, Campbell, Paul, additional, Tedesco, Joseph L., additional, Culbertson, James, additional, VanMil, Brenda, additional, Myers-Ward, R. L., additional, Eddy, Charles, additional, Moon, Jeong, additional, Curtis, D, additional, Hu, M, additional, Wong, D, additional, McGuire, C, additional, Robinson, Joshua, additional, Fanton, Mark, additional, Stitt, T., additional, Snyder, David, additional, Wang, X., additional, and Frantz, Eric, additional

Published
2009
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33. Microhardness of 6H- and 4H-SiC Substrates

Author

Eddy, Charles R., primary, Wu, Ping, additional, Zwieback, Ilya, additional, VanMil, Brenda L., additional, Myers-Ward, Rachael L., additional, Tedesco, Joseph L., additional, Souzis, Andrew E., additional, and Gaskill, D. Kurt, additional

Published
2009
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34. Graphene Formation on SiC Substrates

Author

VanMil, Brenda L., primary, Myers-Ward, Rachael L., additional, Tedesco, Joseph L., additional, Eddy, Charles R., additional, Jernigan, Glenn G., additional, Culbertson, James C., additional, Campbell, Paul M., additional, McCrate, J.M., additional, Kitt, S.A., additional, and Gaskill, D. Kurt, additional

Published
2009
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43. Nanocrystalline diamond films as UV-semitransparent Schottky contacts to 4H-SiC

Author

Tadjer, Marko J., primary, Hobart, Karl D., additional, Caldwell, Joshua D., additional, Butler, James E., additional, Liu, Kendrick X., additional, Eddy, Charles R., additional, Gaskill, D. Kurt, additional, Lew, K. K., additional, VanMil, Brenda L., additional, Myers-Ward, Rachael L., additional, Ancona, Mario G., additional, Kub, Fritz J., additional, and Feygelson, Tatyana I., additional

Published
2007
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50. Exploring the Optical Properties of HgCdSe Films Using IR-Spectroscopic Ellipsometry.

Author

Peiris, F.C., Brill, G., Doyle, Kevin, VanMil, Brenda, and Myers, Thomas

Subjects
OPTICAL properties, DIELECTRIC devices, ELLIPSOMETRY, DIELECTRIC measurements, CRYSTAL oscillators
Abstract

We have used infrared spectroscopic ellipsometry to interrogate the dielectric response of a series of HgCdSe samples in a spectral range between 2000 and 40000 nm. Using a standard inversion technique, the experimental data obtained at multiple angles of incidence were modeled to deduce the dielectric function of each sample. The dielectric functions obtained for HgCdSe samples allowed us to predict the band gaps for the samples, which increase as a function of the Cd concentration. Next, we modeled the dielectric function as a collection of oscillators, each of which represented a particular transition manifested in the spectrum. The most significant result obtained from this work is the recovery of their doping characteristics from the ellipsometric data. Specifically, two HgCdSe samples with x = 0.21 and 0.28, grown on GaSb substrates, show a carrier concentration of 1.6 × 10 and 1.8 × 10 cm, respectively. These results are particularly helpful because conventional Hall measurements cannot be used for these specific samples due to the substrates (i.e., GaSb) used to grow them being highly conductive. [ABSTRACT FROM AUTHOR]

Published
2014
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