Narayanamurti, Venkatesh

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Narayanamurti, Venkatesh

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Narayanamurti

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Venkatesh

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Narayanamurti, Venkatesh

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University-Industry Collaboration in Science and Technology in Kuwait and the United Arab Emirates
(Belfer Center for Science and International Affairs, 2017-03) Stern, Rebecca; Siddiqi, Afreen; Diaz Anadon, Laura; Narayanamurti, Venkatesh
Policymakers in the Gulf region recognize the importance of strengthening science and technology (S&T) to boost competitiveness and economic development. A number of efforts have been made in recent years to bolster higher education, establish technology parks, and invest in regional research and development (R&D). Collaboration between local universities and the private sector is instrumental to advancing S&T and the national innovation agenda, and countries in the Gulf have the opportunity to benefit from enhancing university-industry linkages (UILs). In order to target policies and identify strategies for increasing UILs, a better understanding about the state, nature, and output of existing linkages is necessary. To address this, our research team at the Harvard Kennedy School’s Belfer Center for Science and International Affairs conducted detailed surveys of faculty and administrative staff at seven leading universities in Kuwait and the UAE. The data of the surveys was analyzed in conjunction with a bibliometric analysis of publications from those seven universities. Additionally, the bibliometric data was collected for three S&T universities in Singapore and three S&T universities in Norway for comparative analysis were chosen as a comparison group to characterize UILs because of their population size, the richness of fossil fuel resources in Norway, and the relatively recent development of Singapore in building a strong innovation ecosystem compared to other OECD countries to characterize UILs. Analysis of the surveys and bibliometrics elucidated new insights about the current state of and future opportunities for strengthening university-industry collaboration in science and engineering. This report presents key findings and concludes with several policy recommendations.
Bandgap and Band Offsets Determination of Semiconductor Heterostructures Using Three-Terminal Ballistic Carrier Spectroscopy
(AIP Publishing, 2009-09-14) Yi, Wei; Narayanamurti, Venkatesh; Lu, Hong; Scarpulla, Michael A.; Gossard, Arthur C.; Huang, Yong; Ryou, Jae-Hyun; Dupuis, Russell D.
Utilizing ambipolar tunnel emission of ballistic electrons and holes, we have developed a model-independent method to self-consistently measure bandgaps of semiconductors and band offsets at semiconductor heterojunctions. Lattice-matched GaAs/AlxGa1-xAs and GaAs/(AlxGa1-x)(0.51)In0.49P(100) single-barrier heterostructures are studied at 4.2 K. For the GaAs/AlGaAs interface, the measured Gamma band offset ratio is 60.4:39.6 (+/- 2%). For the heteroanion GaAs/AlGaInP (100) interface, this ratio varies with the Al composition and is distributed more in the valence band. The indirect-gap X band offsets observed at the GaAs/AlGaInP interface deviates from predictions by the transitivity rule.
Transistors Formed from a Single Lithography Step Using Information Encoded in Topography
(Wiley-Blackwell, 2010) Dickey, Michael D.; Russell, Kasey; Lipomi, Darren J.; Narayanamurti, Venkatesh; Whitesides, George
This paper describes a strategy for the fabrication of functional electronic components (transistors, capacitors, resistors, conductors, and logic gates but not, at present, inductors) that combines a single layer of lithography with angle-dependent physical vapor deposition; this approach is named topographically encoded microlithography (abbreviated as TEMIL). This strategy extends the simple concept of ‘shadow evaporation’ to reduce the number and complexity of the steps required to produce isolated devices and arrays of devices, and eliminates the need for registration (the sequential stacking of patterns with correct alignment) entirely. The defining advantage of this strategy is that it extracts information from the 3D topography of features in photoresist, and combines this information with the 3D information from the angle-dependent deposition (the angle and orientation used for deposition from a collimated source of material), to create ‘shadowed’ and ‘illuminated’ regions on the underlying substrate. It also takes advantage of the ability of replica molding techniques to produce 3D topography in polymeric resists. A single layer of patterned resist can thus direct the fabrication of a nearly unlimited number of possible shapes, composed of layers of any materials that can be deposited by vapor deposition. The sequential deposition of various shapes (by changing orientation and material source) makes it possible to fabricate complex structures—including interconnected transistors—using a single layer of topography. The complexity of structures that can be fabricated using simple lithographic features distinguishes this procedure from other techniques based on shadow evaporation.
DOE FY 2011 Budget Request for Energy Research, Development, Demonstration, and Deployment: Analysis and Recommendations
(Belfer Center for Science and International Affairs, Harvard Kennedy School, 2010) Anadon, Laura Diaz; Bunn, Matthew; Chan, Gabriel; Chan, Melissa; Gallagher, Kelly Sims; Jones, Charles; Kempener, Ruud; Lee, Audrey; Narayanamurti, Venkatesh
Confinement-Enhanced Electron Transport across a Metal-Semiconductor Interface
(American Physical Society (APS), 2001) Altfeder, I. B.; Golovchenko, Jene; Narayanamurti, Venkatesh
We present a combined scanning tunneling microscopy and ballistic electron emission microscopy study of electron transport across an epitaxial Pb/Si(111) interface. Experiments with a self-assembled Pb nanoscale wedge reveal the phenomenon of confinement-enhanced interfacial transport: a proportional increase of the electron injection rate into the semiconductor with the frequency of electron oscillations in the Pb quantum well.
High-Current-Density Monolayer CdSe/ZnS Quantum Dot Light-Emitting Devices with Oxide Electrodes
(Wiley-Blackwell, 2011) Likovich, Edward Michael; Jaramillo, Rafael; Russell, Kasey; Ramanathan, Shriram; Narayanamurti, Venkatesh
Patterned growth of single-walled carbon nanotube arrays from a vapor-deposited Fe catalyst
(AIP Publishing, 2003) Peng, H. B.; Ristroph, T. G.; Schurmann, G. M.; King, G. M.; Yoon, J.; Narayanamurti, Venkatesh; Golovchenko, Jene
Single-walled carbon nanotubes have been grown on a variety of substrates by chemical vapor deposition using low-coverage vacuum-deposited iron as a catalyst. Ordered arrays of suspended nanotubes ranging from submicron to several micron lengths have been obtained on Si, SiO2,SiO2, Al2O3,Al2O3, and Si3N4Si3N4 substrates that were patterned on hundred nanometer length scales with a focused ion beam machine. Electric fields applied during nanotubegrowth allow the control of growth direction. Nanotube circuits have been constructed directly on contacting metal electrodes of Pt/Cr patterned with catalysts. Patterning with solid iron catalyst is compatible with modern semiconductor fabrication strategies and may contribute to the integration of nanotubes in complex device architectures.
Scientific Wealth in Middle East and North Africa: Productivity, Indigeneity, and Specialty in 1981–2013
(Public Library of Science, 2016) Siddiqi, Afreen; Stoppani, Jonathan; Anadon, Laura Diaz; Narayanamurti, Venkatesh
Several developing countries seek to build knowledge-based economies by attempting to expand scientific research capabilities. Characterizing the state and direction of progress in this arena is challenging but important. Here, we employ three metrics: a classical metric of productivity (publications per person), an adapted metric which we denote as Revealed Scientific Advantage (developed from work used to compare publications in scientific fields among countries) to characterize disciplinary specialty, and a new metric, scientific indigeneity (defined as the ratio of publications with domestic corresponding authors) to characterize the locus of scientific activity that also serves as a partial proxy for local absorptive capacity. These metrics—using population and publications data that are available for most countries–allow the characterization of some key features of national scientific enterprise. The trends in productivity and indigeneity when compared across other countries and regions can serve as indicators of strength or fragility in the national research ecosystems, and the trends in specialty can allow regional policy makers to assess the extent to which the areas of focus of research align (or not align) with regional priorities. We apply the metrics to study the Middle East and North Africa (MENA)—a region where science and technology capacity will play a key role in national economic diversification. We analyze 9.8 million publication records between 1981–2013 in 17 countries of MENA from Morocco to Iraq and compare it to selected countries throughout the world. The results show that international collaborators increasingly drove the scientific activity in MENA. The median indigeneity reached 52% in 2013 (indicating that almost half of the corresponding authors were located in foreign countries). Additionally, the regional disciplinary focus in chemical and petroleum engineering is waning with modest growth in the life sciences. We find repeated patterns of stagnation and contraction of scientific activity for several MENA countries contributing to a widening productivity gap on an international comparative yardstick. The results prompt questions about the strength of the developing scientific enterprise and highlight the need for consistent long-term policy for effectively addressing regional challenges with domestic research.
Scattering-Assisted Tunneling: Energy Dependence, Magnetic Field Dependence, and Use as an External Probe of Two-Dimensional Transport
(American Physical Society, 2010) Russell, Kasey; Capasso, Federico; Narayanamurti, Venkatesh; Lu, H.; Zide, J. M. O.; Gossard, A. C.
For more than three decades, research on tunneling through planar barriers has focused principally on processes that conserve momentum parallel to the barrier. Here we investigate transport in which scattering destroys lateral momentum conservation and greatly enhances the tunneling probability. We have measured its energy dependence using capacitance spectroscopy, and we show that for electrons confined in a quantum well, the scattering enhancement can be quenched in an applied magnetic field, enabling this mechanism to function as an external probe of the origin of the quantum Hall effect.
Transforming U.S. Energy Innovation
(Belfer Center for Science and International Affairs, Harvard Kennedy School, 2011) Diaz Anadon, Laura; Bunn, Matthew; Chan, Melissa; Jones, Charles; Kempener, Ruud; Chan, Gabriel Angelo; Lee, Audrey; Logar, Nathaniel James; Narayanamurti, Venkatesh
The United States and the world need a revolution in energy technology—a revolution that would improve the performance of our energy systems to face the challenges ahead. A dramatic increase in the pace of energy innovation is crucial to meet the challenges of: • Energy and national security, to address the dangers of undue reliance on dwindling supplies of oil increasingly concentrated in some of the most volatile regions of the world, and to limit the connection between nuclear energy and the spread of nuclear weapons; • Environmental sustainability, to reduce the wide range of environmental damages due to energy production and use, from fine particulate emissions at coal plants, to oil spills, to global climate disruption; and • Economic competitiveness, to seize a significant share of the multi-trillion-dollar clean energy technology market and improve the balance of payments by increasing exports, while reducing the hundreds of billions of dollars spent every year on importing oil. In an intensely competitive and interdependent global landscape, and in the face of large climate risks from ongoing U.S. reliance on a fossil-fuel based energy system, it is important to maintain and expand long-term investments in the energy future of the U.S. even at a time of budget stringency. It is equally necessary to think about how to improve the efficiency of those investments, through strengthening U.S. energy innovation institutions, providing expanded incentives for private-sector innovation, and seizing opportunities where international cooperation can accelerate innovation. The private sector role is key: in the United States the vast majority of the energy system is owned by private enterprises, whose innovation and technology deployment decisions drive much of the country’s overall energy systems. Efficiently utilizing government investments in energy innovation requires understanding the market incentives that drive private firms to invest in advanced energy technologies, including policy stability and predictability. The U.S. government has already launched new efforts to accelerate energy innovation. In particular, the U.S. Department of Energy is undertaking a Quadrennial Technology Review to identify the most promising opportunities and provide increased coherence and stability. Our report offers analysis and recommendations designed to accelerate the pace at which better energy technologies are discovered, developed, and deployed, and is focused in four key areas: • Designing an expanded portfolio of federal investments in energy research, development, demonstration (ERD&D), and complementary policies to catalyze the deployment of novel energy technologies; • Increasing incentives for private-sector innovation and strengthening federal-private energy innovation partnerships; • Improving the management of energy innovation institutions to maximize the results of federal investments; and • Expanding and coordinating international energy innovation cooperation to bring ideas and resources together across the globe to address these global challenges.