Samit K. Ray

Bio: Samit K. Ray is an academic researcher from Indian Institute of Technology Kharagpur. The author has contributed to research in topics: Photoluminescence & Thin film. The author has an hindex of 44, co-authored 507 publications receiving 8085 citations. Previous affiliations of Samit K. Ray include University of Delaware & Indian Institute of Technology Kanpur.

Ga2O3(Gd2O3) film as high-k gate dielectric for SiGe MOSFET devices

Abstract: Dielectric films from gadolinium gallium garnet single crystal were deposited by electron-beam evaporation on strained Si1-xGex/Si layers at 300 K to form high-k metal-insulator-semiconductor (MIS) structures The p-Si074Ge026/Ga2O3(Gd2O3) interface properties were studied through C-V and G-V measurements of the MIS capacitors, which showed encouraging electrical characteristics with oxide k = 123 and minimum interface state density Dit of 48 × 1011 cm-2eV-1

Charge trapping characteristics of ultrathin oxynitrides on Si/Si1-x-yGexCy/Si heterolayers

Abstract: Ultrathin oxynitride films have been grown on partially strain compensated Si/Si 1− x − y Ge x C y /Si layers by microwave plasma at a low temperature. Significant improvements in charge-to-breakdown ( Q BD ) and charge trapping under static and dynamic electric field stress are observed for O 2 /NH 3 /NO-plasma treated films due to efficient removal of H species from the interface. The trapped charge generation and charge centroid show a frequency dependence for bipolar stress and polarity dependence in case of unipolar stress.

Influence of untreated and novel electron beam modified surface coated silica filler on rheometric and mechanical properties of ethylene-octene copolymer

Abstract: Surface modified silica fillers have been developed by coating these with a silane coupling agent, triethoxyvinyl silane (TEVS) followed by electron beam irradiation at room temperature. These have been incorporated in an ethylene-octene copolymer rubber. Rheometric, mechanical, volume swelling and aging properties of the gum as well as the filled elastomers have been studied in details. A significant improvement in the above properties has been noticed for these vulcanizates, which clearly emphasizes that novel surface modified silica improves polymer-filler adhesion by the introduction of covalent bonds between the filler surface and the rubber chains. Filler-filler and polymer-filler interactions have been quantified with the help of a mathematical model correlating the modulus and the volume concentration of filler. The influence of electron beam treatment on silanized silica filler has also been demonstrated from the above model.

Vapor condensation growth and evolution mechanism of ZnO nanorod flower structures

Abstract: ZnO flower-like nanostructures were grown on Ge (100) substrate, by a modified chemical vapor condensation technique of zinc acetate dihydrate at 300 °C, without using any catalyst. These self-organized three-dimensional nanostructures were composed of hierarchical arrangement of ZnO nanorods of diameter ~50 nm around a common nucleus and were distributed uniformly over the entire substrate surface. Evolution study of these structures indicates that the growth begins with a two-dimensional planar arrangement of (0001)-oriented ZnO nanorods. With increasing growth time, the expanding adjacent two-dimensional growth fronts approach each other, followed by which, the formation of three-dimensional flower-like structures evolve. Surface diffusion mechanism seems to play an important role in forming these nanostructures, which has been discussed in detail. Elaborate electron microscopic (SEM, TEM) techniques have been used to investigate the growth characteristics of the flower structures. The photoluminescence measurements showed pure free excitonic transition centered at about 3.249 eV with full width at half-maximum of about 141 meV at 300 K, which blue shifted to 3.361 eV at 10 K with corresponding half width of 7 meV with no defect-related bandgap peak due to relatively low growth temperature. The optical emission area was imaged through a cathodoluminescence technique. Scanning electron micrograph of a typical ZnO nanorod flower structure grown at 300 °C on Ge (100).

Ultrafast real-time observation of double Fano resonances in discrete excitons and single plasmon-continuum

Abstract: Ultrafast observation of multiple asymmetric Fano line shapes in energetically overlapped single continuum and multiple discrete states is of great theoretical interest in different domains of physics, though their real-time experimental demonstrations are yet to be achieved. Here, we present an experimental observation on time-domain response of the double Fano asymmetries in a metal--two-dimensional semiconductor hybrid prototype at room temperature. The ultrafast interactions in two discrete spin-resolved excitons of ${\mathrm{MoS}}_{2}$ and a single metal plasmon-continuum allow us to observe the generation and evolution of the double Fano line profiles in real time. Apart from the subpicosecond development of double Fano line shapes, we calculate all the time-dependent nonlinear double Fano parameters. These results suggest a better understanding of ultrafast Fano physics in condensed-matter systems and have potential prospects in ultrafast photonic devices using double Fano resonances even at room temperature.

Prospects of Colloidal Nanocrystals for Electronic and Optoelectronic Applications

Abstract: Nanocrystals (NCs) discussed in this Review are tiny crystals of metals, semiconductors, and magnetic material consisting of hundreds to a few thousand atoms each. Their size ranges from 2-3 to about 20 nm. What is special about this size regime that placed NCs among the hottest research topics of the last decades? The quantum mechanical coupling * To whom correspondence should be addressed. E-mail: dvtalapin@uchicago.edu. † The University of Chicago. ‡ Argonne National Lab. Chem. Rev. 2010, 110, 389–458 389

Principles Of Fluorescence Spectroscopy

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Nanoscale metal oxide-based heterojunctions for gas sensing: A review

Abstract: Metal oxide-based resistive-type gas sensors are solid-state devices which are widely used in a number of applications from health and safety to energy efficiency and emission control. Nanomaterials such as nanowires, nanorods, and nanoparticles have dominated the research focus in this field due to their large number of surface sites facilitating surface reactions. Previous studies have shown that incorporating two or more metal oxides to form a heterojunction interface can have drastic effects on gas sensor performance, especially the selectivity. Recently, these effects have been amplified by designing heterojunctions on the nano-scale. These designs have evolved from mixed commercial powders and bi-layer films to finely-tuned core–shell and hierarchical brush-like nanocomposites. This review details the various morphological classes currently available for nanostructured metal-oxide based heterojunctions and then presents the dominant electronic and chemical mechanisms that influence the performance of these materials as resistive-type gas sensors. Mechanisms explored include p–n and n–n potential barrier manipulation, n–p–n response type inversions, spill-over effects, synergistic catalytic behavior, and microstructure enhancement. Tables are presented summarizing these works specifically for SnO2, ZnO, TiO2, In2O3, Fe2O3, MoO3, Co3O4, and CdO-based nanocomposites. Recent developments are highlighted and likely future trends are explored.

Diversity of life

Abstract: It is clear that the above can lead to confusion when scientists of different countries are trying to communicate with each other. Another example is the burrowing rodent called a gopher found throughout the western United States. In the southeastern United States the term gopher refers to a burrowing turtle very similar to the desert tortoise found in the American southwest. One final example; two North American mammals known as the elk and the caribou are known in Europe as the reindeer and the elk. We never sing “Rudolph the Red-nosed elk”! Confused? This was the reason for creating an internationally recognized system of naming organisms. To avoid confusion, living organisms are assigned a scientific name based on Latin or Latinized words. The English sparrow is Passer domesticus or Passer domesticus (italics or underlining these two names is the official written representation of a scientific name). Using a uniform naming system allows scientists from all over the world to recognize exactly which life form a scientist is referring to. The naming process is called the binomial system of nomenclature. Passer is comparable to a surname and is called the genus, while domesticus is the specific or species name (like your given name) of the English sparrow. Now scientists can give all sparrow-like birds the genus Passer but the species name will vary. All similar genera (plural for genus) can be grouped into another, “higher” category (see below). Study the following for a more through understanding of taxonomy. Taxonomy Analogy Kingdom: Animalia Country

Environmental applications of graphene-based nanomaterials.

Abstract: Graphene-based materials are gaining heightened attention as novel materials for environmental applications The unique physicochemical properties of graphene, notably its exceptionally high surface area, electron mobility, thermal conductivity, and mechanical strength, can lead to novel or improved technologies to address the pressing global environmental challenges This critical review assesses the recent developments in the use of graphene-based materials as sorbent or photocatalytic materials for environmental decontamination, as building blocks for next generation water treatment and desalination membranes, and as electrode materials for contaminant monitoring or removal The most promising areas of research are highlighted, with a discussion of the main challenges that we need to overcome in order to fully realize the exceptional properties of graphene in environmental applications