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.

Selective photoresponse of plasmonic silver nanoparticle decorated Bi 2 Se 3 nanosheets

Abstract: The plasmon-enhanced photoresponse properties of a Ag-nanoparticle-decorated-Bialt;subagt;2alt;/subagt;Sealt;subagt;3alt;/subagt;-nanosheet (AGBS)/p-Si heterojunction device have been studied. The Ag nanoparticles, the Bialt;subagt;2alt;/subagt;Sealt;subagt;3alt;/subagt; nanosheets, and the AGBS nanocomposite are synthesized chemically. Microscopic investigations, ultimately of the AGBS nanocomposite, reveal that the Bialt;subagt;2alt;/subagt;Sealt;subagt;3alt;/subagt; nanosheets of thickness ~ 20 nm and lateral dimension ~ 1 ?m are decorated with Ag nanoparticles of sizes 20 - 40 nm in the nanocomposite. The X-ray diffraction pattern of AGBS shows that apart from being in the metallic state, Ag in AGBS is also in the form of compounds with Bi, Se, and additionally O. This observation is further complemented by the X-ray photoelectron spectrum, which shows the presence of Agalt;supagt;0alt;/supagt; and Agalt;supagt;+alt;/supagt; states of Ag in AGBS. The UV-visible absorption spectra show the plasmonic peak of the Ag nanoparticles to occur at 420 nm; the peak is shifted to ~ 500 nm in AGBSa#13; due to the modified dielectric environment of the nanoparticles. The AGBS/p-Si heterojunction shows excellent photoresponse properties, with a responsivity of 0.28 A/W, a fairly high detectivity of 4×10alt;supagt;10alt;/supagt; Jones, and an EQE of 71% under 10 V reverse bias at 500 nm wavelength. The plasmon enhanced photoresponse at the selective wavelength makes this material attractive for high performancea#13; optoelectronic devices.

NO/O2/NO plasma grown oxynitride films on silicon

Abstract: The electrical properties of high quality ultrathin (< 100A) oxide and oxynitride films grown on silicon at low temperature using O 2 , NO and NO/O 2 /NO-plasma are reported. A significant improvement in the dielectric endurance and charge trapping behavior under Fowier-Nordheim (F-N) constant current stressing is observed for NO/O 2 /NO grown oxynitride films.

THz lasing due to resonant acceptor states in strained p‐Ge and SiGe quantum‐well structures

Abstract: An intense THz emission was observed from strained SiGe/Si quantum-well structures under a strong pulsed electric field. The p-type structures were MBE-grown on n-type Si substrates and δ-doped with boron. Lines with wavelengths near 100 microns were observed in the emission spectrum. The modal structure in the spectrum gave evidence for the stimulated nature of the emission. The origin of the THz emission was attributed to intra-center optical transitions between resonant and localized boron levels similar to that in compressed p-Ge.

Phase Inhomogeneity and Electrical Characteristics of Nickel Silicide Schottky Contacts Formed on 4H-SiC

Abstract: Nickel silicide Schottky contacts were formed on 4H-SiC by consecutive deposition of a titanium adhesion layer, 4 nm thick, and nickel, 100 nm thick, followed by annealing at temperatures from 600 to 750 °C. It was found that contacts with barrier heights of 1.45 eV, consisting mainly of NiSi phase, formed in the 600-660 °C temperature range, while annealing at around 750 °C led to the formation of Ni2Si phase with barrier heights of 1.1 eV. Annealing at intermediate temperatures resulted in the nucleation of Ni2Si grains embedded in the NiSi film which were directly observed by micro-Raman mapping. It was concluded that the thermodynamically unfavourable NiSi phase appeared in the 600-660 °C temperature range due to the fact that the solid state chemical reaction between Ni and SiC at these temperatures is controlled by nickel diffusion through the titanium barrier.

Hall mobilities in B-doped strained Si1−xGex and Si1−x−yGexCy layers grown by ultrahigh vacuum chemical vapor deposition

Abstract: Hall mobilities in a temperature range of 80–300 K have been measured in fully strained Si1−xGex and partially strain-compensated p-type Si1−x−yGexCy alloy layers grown on Si (100) by ultrahigh vacuum chemical vapor deposition. The effect of the addition of C on strain compensation of Si1−xGex films has been studied by high-resolution x-ray diffraction analysis. The Hall hole mobility is found to increase with decreasing compensative strain or effective Ge content in the layer throughout the studied temperature range. The effect of a Si-cap layer on the hole mobility of Si1−x−yGexCy film has been investigated.

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