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Vivek Subramanian

Bio: Vivek Subramanian is an academic researcher from University of California, Berkeley. The author has contributed to research in topics: Printed electronics & Thin-film transistor. The author has an hindex of 62, co-authored 271 publications receiving 16514 citations. Previous affiliations of Vivek Subramanian include SanDisk & University of Texas at Austin.


Papers
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Patent
06 Dec 2002
TL;DR: In this article, a very high density field programmable memory (FPM) is described. And the array is formed vertically above a substrate using several layers, each layer of which includes vertically fabricated memory cells.
Abstract: A very high density field programmable memory is disclosed. An array is formed vertically above a substrate using several layers, each layer of which includes vertically fabricated memory cells. The cell in an N level array may be formed with N+1 masking steps plus masking steps needed for contacts. Maximum use of self alignment techniques minimizes photolithographic limitations. In one embodiment the peripheral circuits are formed in a silicon substrate and an N level array is fabricated above the substrate.

1,212 citations

Journal ArticleDOI
16 Jan 2008-Langmuir
TL;DR: Under appropriate conditions, the coffee ring effect is able to enhance or eliminate in the authors' drying features by controlling the evaporation profile of drying drops and lines.
Abstract: We have studied inkjet-printed drops of a conductive polymer. We show how varying drop spacing and temperature lead to several different printed line morphologies and offer a simple geometric explanation for these various forms. Also, by controlling the evaporation profile of drying drops and lines, we demonstrate control of the coffee ring effect by which solute is transferred to the rim. Under appropriate conditions, we are able to enhance or eliminate the coffee ring effect in our drying features.

892 citations

Journal ArticleDOI
TL;DR: Interestingly, SEM, TEM, and HRTEM revealed a variety of structures ranging from nanostructured surface with a distinct platelike morphology to nanorod depending upon the hydrothermal reaction time employed during the preparation of the manganese oxide: increasing the amount of individual nanorods in the materials prepared with longer hydrother mal reaction time.
Abstract: The effect of varying the hydrothermal time to synthesize manganese oxide (MnO(2)) nanostructures was investigated along with their influence on structural, morphological, compositional, and electrochemical properties in supercapacitor electrode materials. XRD and TEM studies showed that the MnO(2) prepared in shorter hydrothermal dwell time was a mixture of amorphous and nanocrystalline particles, and there was an evolution of crystallinity of the nanostructures as the dwell time increased from 1 to 18 h. Interestingly, SEM, TEM, and HRTEM revealed a variety of structures ranging from nanostructured surface with a distinct platelike morphology to nanorods depending upon the hydrothermal reaction time employed during the preparation of the manganese oxide: increasing the amount of individual nanorods in the materials prepared with longer hydrothermal reaction time. The surface area of the synthesized nanomaterials varied from 100 to 150 m(2)/g. Electrochemical properties were evaluated using cyclic voltammetry (CV) and galvanostatic charge-discharge studies, and the capacitance values were in the range 72-168 F/g depending upon synthesis conditions. The formation mechanism of the nanorods and their impact on the specific capacitance were discussed in detail.

871 citations

Journal ArticleDOI
TL;DR: In this article, the use of metal and metal oxide-containing inks in the preparation of contacts and interconnects is discussed, as well as the challenges associated with processing these types of inks and ways to successfully obtain the desired features.
Abstract: Printed electronics represent an emerging area of research that promises large markets due to the ability to bypass traditional expensive and inflexible silicon-based electronics to fabricate a variety of devices on flexible substrates using high-throughput printing approaches. This article presents a summary of work to date in the field of printed electronics and the materials chemistry involved. In particular, the focus is upon the use of metal- and metal oxide-containing inks in the preparation of contacts and interconnects. The review discusses the challenges associated with processing these types of inks and ways to successfully obtain the desired features.

670 citations

Proceedings ArticleDOI
01 Dec 1999
TL;DR: In this article, a self-aligned double-gate MOSFET structure (FinFET) is used to suppress the short channel effect, and a 45 nm gate-length PMOS FinEET is presented.
Abstract: High performance PMOSFETs with gate length as short as 18-nm are reported. A self-aligned double-gate MOSFET structure (FinFET) is used to suppress the short channel effect. A 45 nm gate-length PMOS FinEET has an I/sub dsat/ of 410 /spl mu/A//spl mu/m (or 820 /spl mu/A//spl mu/m depending on the definition of the width of a double-gate device) at Vd=Vg=1.2 V and Tox=2.5 nm. The quasi-planar nature of this variant of the double-gate MOSFETs makes device fabrication relatively easy using the conventional planar MOSFET process technologies. Simulation shows possible scaling to 10-nm gate length.

550 citations


Cited by
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Journal ArticleDOI
TL;DR: This work has shown that combination of pseudo-capacitive nanomaterials, including oxides, nitrides and polymers, with the latest generation of nanostructured lithium electrodes has brought the energy density of electrochemical capacitors closer to that of batteries.
Abstract: Electrochemical capacitors, also called supercapacitors, store energy using either ion adsorption (electrochemical double layer capacitors) or fast surface redox reactions (pseudo-capacitors). They can complement or replace batteries in electrical energy storage and harvesting applications, when high power delivery or uptake is needed. A notable improvement in performance has been achieved through recent advances in understanding charge storage mechanisms and the development of advanced nanostructured materials. The discovery that ion desolvation occurs in pores smaller than the solvated ions has led to higher capacitance for electrochemical double layer capacitors using carbon electrodes with subnanometre pores, and opened the door to designing high-energy density devices using a variety of electrolytes. Combination of pseudo-capacitive nanomaterials, including oxides, nitrides and polymers, with the latest generation of nanostructured lithium electrodes has brought the energy density of electrochemical capacitors closer to that of batteries. The use of carbon nanotubes has further advanced micro-electrochemical capacitors, enabling flexible and adaptable devices to be made. Mathematical modelling and simulation will be the key to success in designing tomorrow's high-energy and high-power devices.

14,213 citations

Journal ArticleDOI
TL;DR: Two important future research directions are indicated and summarized, based on results published in the literature: the development of composite and nanostructured ES materials to overcome the major challenge posed by the low energy density.
Abstract: In this critical review, metal oxides-based materials for electrochemical supercapacitor (ES) electrodes are reviewed in detail together with a brief review of carbon materials and conducting polymers. Their advantages, disadvantages, and performance in ES electrodes are discussed through extensive analysis of the literature, and new trends in material development are also reviewed. Two important future research directions are indicated and summarized, based on results published in the literature: the development of composite and nanostructured ES materials to overcome the major challenge posed by the low energy density of ES (476 references).

7,642 citations

Journal ArticleDOI
TL;DR: Electronic Coupling in Oligoacene Derivatives: Factors Influencing Charge Mobility, and the Energy-Splitting-in-Dimer Method 3.1.
Abstract: 2.2. Materials 929 2.3. Factors Influencing Charge Mobility 931 2.3.1. Molecular Packing 931 2.3.2. Disorder 932 2.3.3. Temperature 933 2.3.4. Electric Field 934 2.3.5. Impurities 934 2.3.6. Pressure 934 2.3.7. Charge-Carrier Density 934 2.3.8. Size/molecular Weight 935 3. The Charge-Transport Parameters 935 3.1. Electronic Coupling 936 3.1.1. The Energy-Splitting-in-Dimer Method 936 3.1.2. The Orthogonality Issue 937 3.1.3. Impact of the Site Energy 937 3.1.4. Electronic Coupling in Oligoacene Derivatives 938

3,635 citations

Journal ArticleDOI
TL;DR: The impact of nanoencapsulation of various disease related drugs on biodegradable nanoparticles such as PLGA, PLA, chitosan, gelatin, polycaprolactone and poly-alkyl-cyanoacrylates is highlighted.

3,116 citations

Journal ArticleDOI
TL;DR: In this paper, the entire process leading to polymer solar cells is broken down into the individual steps and the available techniques and materials for each step are described with focus on the particular advantages and disadvantages associated with each case.

3,090 citations