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.

Fe x Ni (1-x) O/NiO Heterojunction-Based Selective VOC Sensor Device by Using Temperature Tunability

Abstract: Monitoring air quality is quintessential for maintaining sound human health. In our work, a p-p heterojunction device based on Fe x Ni(1-x)O/NiO was fabricated via mild solvent based approach. The device was subjected to calculated concentrations of VOC vapors (viz. 2-propanol, toluene and formaldehyde) at varying operating temperatures between 150 °C and 350 °C. It was seen that the sensor could be made selective towards the different VOCs (e.g. 2-propanol at 200 °C, toluene at 250 °C and formaldehyde at 300 °C) by tuning the operating temperature. The sensor response was maximum for formaldehyde (2.1 with 76 ppm) and was found to be reasonably fast (response time 58 sec and recovery time 46 sec). The theoretical LOD was obtained as 0.77 ppm for 2-propanol, 0.83 ppm for toluene and 0.78 ppm for formaldehyde. Thus, it was possible for selectively sense different VOCs by a single sensor device by varying its operating temperature which may introduce a smart sensing solution with high market feasibility in the future.

Growth of Ge nanoislands on Si (001) using molecular beam epitaxy

Abstract: Self-assembled nano-sized Ge islands have been grown on Si (001) substrates using a solid source molecular beam epitaxy Detailed island morphological studies at different deposition temperatures and flux rate of as-grown and annealed nanocrystals are reported Both the alloy composition and in-plane strain in the grown islands have been determined from high-resolution XRD and Raman study The shape and size of the grown islands and the coarsening mechanism are explicitly discussed with the help of data obtained from AFM topographic images The current-voltage characteristics of a single isolated island exhibits Coulomb blockade behaviour at room temperature

Ion Assisted Growth and Characterization of Polycrystalline Silicon and Silicon-Germanium Films

Abstract: Polysilicon films have been deposited at a low temperature by single and dual ion beam sputtering. The structural and electrical properties of as-deposited and annealed films have been characterized by X-ray diffraction, secondary ion mass spectroscopy, atomic force microscopy and Hall mobility measurements at room temperature as well as low temperature region (290°K-70°K). The study revealed that the films are microcrystalline with average grain size ranging from 200 A to 400 A. The films exposed to low energy secondary ion beam during deposition has exhibited smoother surface topography and better electrical properties than that of films deposited without any secondary ion bombardment. Some preliminary results on ion beam sputtered SiGe films using a composite target (Si, Ge) have also been presented.

Synthesis, Properties and Applications of Polymeric Matrix-Based Phosphor Hybrids

Abstract: AbstractPhosphors are special types of compounds which emit lights when exposed to visible light, ultraviolet radiation or electron beam. In general, these compounds are prepared from inorganic transition metal or rare earth compounds. The radiation causes movement of its valence electron to the conduction or exciton band leaving behind a hole in the valence band. The electron–hole pairs moves to the impurities in the crystal of the phosphor which rapidly de-excite by emitting light. The inhomogeneity in the crystal structure of phosphor is created by addition of the impurities or dopants which is also called activator. Accordingly, a phosphor consists of a host which is oxides, nitrides, sulfides, halides, silicates or selenides of Zn, Cd, Mn, Al, Si or different rare earth metals and an activator metal such as Cu or Ag activated ZnS or Bi activated CaS phosphor. Apart from inorganic phosphors, more energy efficient phosphors for lighting and other optoelectronic applications are prepared from metal–organic frameworks (MOF) or coordination polymers. MOF consists of single metal ions or clusters of metal ions linked by organic ligands having multiple binding sites to form extended network structures. However, the inorganic or MOF based phosphors have several drawbacks like limited resources, high toxicity and also high cost. In contrast to inorganic or MOF based phosphors, metal-free small organic molecules or polymer based room temperature phosphors (RTP) are environment friendly and easy to process. These two types of RTPs are characterized by its long-lived triplet excitons and larger Stokes shift. However, easy processing, good flexibility and stretching ability, low cost, excellent electron mobility and thermal conductivity have made polymer based RTPs more attractive than small organic molecules based RTPs. Thus, Polymer based RTPs are widely used in organic light emitting diodes, solar cells, field effect transistors, memory devices and many other similar applications. The phosphors are prepared by (1) intersystem crossing (ICS) from the lowest excited singlet state (S1) to a triplet state (Tn) and (2) radiative transition from the lowest excited triplet state (T1) to the ground state (S0). The emission from T1 state is quenched at room temperature under ambient conditions. Accordingly, the challenge to get efficient RTP is to suppress nonradiative decay. Polymers are of high molecular weight with long chains that can cause entanglement and a high degree of rigidity making them ideal candidates to observe phosphorescence from organic lumiphores. In this book chapter synthesis, properties and applications of (1) non-doped and (2) doped polymer based RTPs will be discussed with reference to recent literature with the following possible.

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

Abstract: Thank you very much for downloading principles of fluorescence spectroscopy. As you may know, people have look hundreds times for their favorite novels like this principles of fluorescence spectroscopy, but end up in malicious downloads. Rather than reading a good book with a cup of tea in the afternoon, instead they cope with some harmful bugs inside their desktop computer. principles of fluorescence spectroscopy is available in our digital library an online access to it is set as public so you can download it instantly. Our digital library spans in multiple locations, allowing you to get the most less latency time to download any of our books like this one. Kindly say, the principles of fluorescence spectroscopy is universally compatible with any devices to read.

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