Publications Portal

You searched on:
Author: Angela Hight Walker

Displaying records 1 to 10 of 72 records.
Resort by: Date / Title

1. Determination of graphene work function and graphene-insulator-semiconductor band alignment by internal photoemission spectroscopy
Published: 7/11/2012
Authors: Rusen Yan, Qin Zhang, Wei Li, Irene G. Calizo, Tian T. Shen, Curt A Richter, Angela R Hight Walker, Xuelei X. Liang, David J Gundlach, Nhan V Nguyen, Huili Grace Xing, Alan Seabaugh
Abstract: We determined the band alignment of a graphene-oxide-silicon structure using internal photoemission spectroscopy. From the flatband voltage and Dirac voltage we infer a 4.3  10e11 cm-2 negative extrinsic charge present on the graphene surface. Als ...
http://nist.gov/manuscript-publication-search.cfm?pub_id=911396

2. Characteristics of Graphene for Quantized Hall Effect Measurements
Published: 6/1/2012
Authors: Randolph E Elmquist, Mariano A. Real, Irene G. Calizo, Brian Griffith Bush, Tian T. Shen, Nikolai Nikolayevich Klimov, David B Newell, Angela R Hight Walker, Randall M. Feenstra
Abstract: This paper describes concepts and measurement techniques necessary for characterization of graphene in the development of graphene-based quantized Hall effect (QHE) devices and resistance standards. We briefly contrast the properties of graphene prod ...
http://nist.gov/manuscript-publication-search.cfm?pub_id=910365

3. Towards clean and crackless transfer of graphene
Published: 1/2/2012
Authors: Xuelei X. Liang, Brent A Sperling, Irene G. Calizo, Guangjun Cheng, Christina Ann Hacker, Qin Zhang, Yaw S Obeng, Kai Yan, Hailin Peng, Qiliang Li, Xiaoxiao Zhu, Hui Yuan, Angela R Hight Walker, Zhongfan Liu, Lianmao Peng, Curt A Richter
Abstract: We present the results of a thorough study of wet chemical methods for transferring chemical vapor deposition grown graphene from the metal growth substrate to a device compatible substrate. Based on these results, we have developed a “modified RCA c ...
http://nist.gov/manuscript-publication-search.cfm?pub_id=908399

4. A Highly Practical Route for Large-Area, Single Layer Graphene from Liquid Carbon Sources such as Benzene and Methanol
Published: 10/28/2011
Authors: Gadipelli Srinivas, Irene G. Calizo, Jamie Ford, Guangjun Cheng, Angela R Hight Walker, Taner Yildirim
Abstract: Through a detailed systematic study, we determined the parameters critical for high-quality, single-layer graphene formation and developed a straightforward synthesis that requires no explosive hydrogen or methane gas flow. The synthesis is further ...
http://nist.gov/manuscript-publication-search.cfm?pub_id=907820

5. Evolution of Microscopic Localization in Graphene in a Magnetic Field: From Scattering Resonances to Quantum Dots.
Published: 1/9/2011
Authors: Suyong S. Jung, Gregory M. Rutter, Nikolai Nikolayevich Klimov, David B Newell, Irene G. Calizo, Angela R Hight Walker, Nikolai B Zhitenev, Joseph A Stroscio
Abstract: Graphene is a unique material displaying high-mobility transport in monolayer-thin films. However, its properties are strongly dependent on interactions with substrates, local charges and environment. Scanned probe microscopies can be used to local ...
http://nist.gov/manuscript-publication-search.cfm?pub_id=905753

6. Monodisperse Gold-Copper bimetallic Nanocubes: Facile One-Step Synthesis with Controllable Sizes and Compositions
Published: 8/16/2010
Authors: Yonglin Liu, Angela R Hight Walker
Abstract: We demonstrate a one-pot polyol strategy for the synthesis of Au - Cu perfect nanocubes. To the best of the authors knowledge, this represents the first-time production of Au - Cu bimetallic nanocubes. By carefully adjusting the reaction parameter ...
http://nist.gov/manuscript-publication-search.cfm?pub_id=904214

7. Separation and Characterization of Double Wall Carbon Nanotube Sub-Populations
Published: 7/8/2010
Authors: JiYeon Huh, Angela R Hight Walker, Hyun Wook Ro, Jan Obrzut, Jeffrey A Fagan
Abstract: We present the separation of surfactant encapsulated double wall carbon nanotubes (DWCNTs) synthesized by the high pressure carbon monoxide decomposition (HiPco) process by length and electronic characteristics using density gradient ultracentrifugat ...
http://nist.gov/manuscript-publication-search.cfm?pub_id=903752

8. Facile One-Pot Synthesis of Metal-Semiconductor Hybrid Nanocrystals via Chemical Transformation: The Case of Cu-CuxS Heterodimers and Hetero-Oligomers
Published: 3/18/2010
Authors: Yonglin Liu, Angela R Hight Walker
Abstract: Metal-semiconductor hybrid nanocrystals (HNCs) hold great potential in the fields of photocatalysis, biomedical imaging, and anticancer nanomedicine. However, their chemical synthetic procedures remain complex and challenging. Here, we apply chemical ...
http://nist.gov/manuscript-publication-search.cfm?pub_id=903039

9. Sample Preparation Protocols for Realization of Reproducible Characterization of Single-walled Carbon Nanotubes
Published: 12/1/2009
Authors: Angela R Hight Walker, Jeffrey A Fagan, Stephanie A Hooker, Michael T Postek, Stephen A Wise, Andras Vladar, Rolf Louis Zeisler
Abstract: Harmonized sample pre-treatment is an integral first step in ensuring metrological quality of measurements as regards repeatability, inter-laboratory reproducibility and commutability. The development of standard preparation methods for SWCNT sample ...
http://nist.gov/manuscript-publication-search.cfm?pub_id=901229

10. The effect of dispersant on defects in length-separated single-wall carbon nanotubes measured by Raman spectroscopy
Published: 11/1/2009
Authors: Jeffrey Ray Simpson, Jeffrey A Fagan, Matthew Becker, Erik K. Hobbie, Angela R Hight Walker
Abstract: The fluorescence quantum yield of single-wall carbon nanotubes (SWCNTs) in solution depends dramatically on dispersant. To evaluate the role of defects in this dependence, we compare Raman spectra from aqueous suspensions of SWCNTs dispersed using ei ...
http://nist.gov/manuscript-publication-search.cfm?pub_id=842611