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.

Pt-functionalized reduced graphene oxide for excellent hydrogen sensing at room temperature

Abstract: Cost effective and faster detection of H2 has always remained a challenge. We report synthesis of reduced graphene oxide (RGO)–Pt composite and its application as highly sensitive and selective H2 sensors at room temperature. Four samples by varying the ratio of RGO and Pt were prepared to test their sensing performance. The tests were carried out in inert (N2) ambience as well as air ambience. It was observed that the RGO:Pt (1:3) 1 h reduced sample demonstrated the best H2 sensing performance in terms of sensitivity, response time, and recovery time at room temperature. Its response varied from ∼19% (200 ppm) to 57% (5000 ppm) against H2 in air ambience. Also, the response time and recovery time of the RGO:Pt (1:3) sample were found to be as fast as 65 s and 230 s against 5000 ppm, respectively, in air ambience. In N2 ambience, the RGO:Pt (1:3) sample demonstrated the best response of −97% (500 ppm), but its recovery was found to be poor. The RGO–Pt composite formation was verified by high resolution transmission electron microscopy and X-ray photoelectron spectroscopy. The detailed physics behind the sensing mechanisms have been explained and experimentally verified in this work.

Bonding, vibrational, and electrical characteristics of CdS nanostructures embedded in polyvinyl alcohol matrix

Abstract: CdS nanocomposites have been grown in polyvinyl alcohol matrix by a chemical synthesis process. The transmission electron micrographs of nanocomposites synthesized at 70–90 °C temperature showed the growth of needlelike and junctionlike nanostructures. X-ray photoelectron spectroscopy analysis revealed the growth of stoichiometric CdS without the formation of any intermediate phases at the CdS-polyvinyl alcohol interface. Raman spectra of first order longitudinal optical phonon peak has been analyzed using phonon dispersion model to detect the surface phonon modes in CdS nanoneedles and wires. The origin of negative differential resistance behavior in current-voltage characteristics for junctionlike CdS nanocomposites has been discussed.

High-k gate oxide for silicon heterostructure MOSFET devices

Abstract: Very exciting and promising results from recent developments in group-IV alloy heterostructures (viz., SiGe, SiGeC, SiC, GeC and strained-Si) have led to the belief that SiGe-based devices will open up an entirely new dimension to the future of VLSI/ULSI technology. The growth of ultrathin dielectric films on a strained group-IV alloy layer is a challenging task. As metal-oxide-semiconductor devices are being aggressively scaled down, high permittivity dielectrics are being widely investigated as alternative gate insulating layers in advanced MOS devices. The present paper reviews the recent results of different gate and high-k dielectrics on group-IV alloy layers for scaled CMOS devices, high-mobility pure-Ge channel devices and nanocrystal floating gate memories.

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