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38 results on '"Biswas, Robin"'

5. Application of Entrainment Velocity Concept for Evaluation of River Morphology: A Numerical Model Study.

Author

Biswas, Robin K., Egashira, Shinji, and Harada, Daisuke

Subjects
SUSPENDED sediments, ADVECTION-diffusion equations, FIELD research, BED load, TWO-dimensional models, SEDIMENT transport
Abstract

Conventionally, fine sediment transport is evaluated in terms of advection-diffusion equation of suspended sediment in which the erosion rate of sediment from the bedload layer plays a significant role. The present study aims to evaluate the riverbed evolution and associated morphological changes in fine sediment dominated Bhairab River of Bangladesh by a depth integrated two-dimensional numerical model. The erosion rate of bed sediment has been evaluated by two approaches. The first approach applies the fall velocity of the sediment particle and equilibrium reference sediment concentration. The other employs the entrainment velocity concept. The results obtained from numerical simulations are verified by the field investigations. The results suggest that the riverbed evolution and morphological changes predicted with the entrainment velocity concept show better agreement with the data obtained from the field investigations. [ABSTRACT FROM AUTHOR]

Published
2024
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6. Electrical properties of high resolution doping structures

Author

Biswas, Robin Gopal

Subjects
530.41, QC Physics
Abstract

The electrical transport properties and device applications of certain high resolution doping structures in silicon are discussed in this thesis. The promise of enhanced device properties from a high resolution doping structure was envisaged through the use of doping supeelattices. These structures are unobtainable by typical high temperature silicon processing technology and are well suited to fabrication by Molecular Beam Epitaxy. The potential for enhanced mobilities in Boron and Antimony doping superlattices has been investigated by the author. Interpretation of mobility data proved complex due to the number of parallel conduction paths, however, some apparent mobility enhancement was found. Sample fabrication during this work has evolved from the use of crude in house contacts, to microfabricated structures produced by the Edinburgh Microfabrication Facility. This allowed the use of well-defined sample geometries and ohmic contacts to buried doping spikes. Conductivity and Hall coefficient studies are continued by a study of Si:Sb layers of widths between 5 to SOOnm. A metal-insulator transition is observed as the width of the dopant spike is reduced to Snm. Further measurements on Si:Sb doping spikes of widths 10,20, 80nm at low temperatures 300mK-25K, have been interpreted through the use of weak localisation and electron-electron interaction corrections to the Boltzmann conductivity. Also obtained through magnetoresistance experiments is the first observation of a 2D to 3D transition in the low temperature electrical properties. The simplest doping profile available in MBE is believed to be one in which the dopant atoms are confined to a few lattice constants, known as a "Delta" layer. This allows the study of two dimensional phenomena in a homoepitaxial system without the presence of an hetero-interface as in the Si-MOSFET. The two dimensional quantisation of the electric subbands in Boron and Antimony delta layers has been investigated via tunnelling spectroscopy. The resultant spectra were found to be consistent with theoretical calculations of subband structure. Finally, the device application of a delta layer was investigated through the development of the first p-channel boron delta doped FET, which may offer advantages for submicron VLSI technology.

Published
1992

10. Understanding Volumetric Water Storage in Monsoonal Wetlands of Northeastern Bangladesh

Author

Ahmad, Shahryar Khalique, primary, Hossain, Faisal, additional, Pavelsky, Tamlin, additional, Parkins, Grant M., additional, Yelton, Sarah, additional, Rodgers, Megan, additional, Little, Sarina, additional, Haldar, Debolina, additional, Ghafoor, Sheikh, additional, Khan, Raihanul Haque, additional, Shawn, Nazmul Ahsan, additional, Haque, Aminul, additional, and Biswas, Robin Kumar, additional

Published
2020
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14. Transconductance and mobility of Si:B delta MOSFET's

Author

Wood, Andrew C.G., O'Neill, Anthony G., Phillips, Peter J., Biswas, Robin G., Whall, Terry E., and Parker, Evan H.C.

Subjects
Metal oxide semiconductor field effect transistors -- Research, Semiconductor doping -- Research, Secondary ion mass spectrometry -- Usage, Business, Electronics, Electronics and electrical industries
Abstract

Boron delta-doped, p-channel, silicon metal oxide semiconductor field effect transistors fabricated via molecular beam epitaxy are reported. A profile of the devices's shift from delta-channel operation to surface-channel operation is made possible by an analysis of the current-voltage characteristics and transconductance measurements. The results also enable the determination of thecarrier mobility during the former mode of operation.

Published
1993

33. Public health service interagency guidelines for screening donors of blood, plasma, organs, tissues, and semen for evidence of hepatitis B and hepatitis C

Author

Alter, Miriam J., primary, Evatt, Bruce L., additional, Margolis, Harold S., additional, Biswas, Robin, additional, Epstein, Jay S., additional, Feinstone, Stephen M., additional, Finlayson, John S., additional, Tankersley, Donald, additional, Alter, Harvey J., additional, and Hoofnagel, Jay H., additional

Published
1991
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35. Electrical properties of high resolution doping structures

Author

Biswas, Robin Gopal

Subjects
Condensed Matter::Materials Science, Condensed Matter::Superconductivity, QC
Abstract

The electrical transport properties and device applications of certain high resolution doping structures in silicon are discussed in this thesis. The promise of enhanced device properties from a high resolution doping structure was envisaged through the use of doping supeelattices. These structures are unobtainable by typical high temperature silicon processing technology and are well suited to fabrication by Molecular Beam Epitaxy. The potential for enhanced mobilities in Boron and Antimony doping superlattices has been investigated by the author. Interpretation of mobility data proved complex due to the number of parallel conduction paths, however, some apparent mobility enhancement was found. Sample fabrication during this work has evolved from the use of crude in house contacts, to microfabricated structures produced by the Edinburgh Microfabrication Facility. This allowed the use of well-defined sample geometries and ohmic contacts to buried doping spikes.\ud \ud Conductivity and Hall coefficient studies are continued by a study of Si:Sb layers of widths between 5 to SOOnm. A metal-insulator transition is observed as the width of the dopant spike is reduced to Snm. Further measurements on Si:Sb doping spikes of widths 10,20, 80nm at low temperatures 300mK-25K, have been interpreted through the use of weak localisation and electron-electron interaction corrections to the Boltzmann conductivity. Also obtained through magnetoresistance experiments is the first observation of a 2D to 3D transition in the low temperature electrical properties.\ud \ud The simplest doping profile available in MBE is believed to be one in which the dopant atoms are confined to a few lattice constants, known as a "Delta" layer. This allows the study of two dimensional phenomena in a homoepitaxial system without the presence of an hetero-interface as in the Si-MOSFET. The two dimensional quantisation of the electric subbands in Boron and Antimony delta layers has been investigated via tunnelling spectroscopy. The resultant spectra were found to be consistent with theoretical calculations of subband structure.\ud Finally, the device application of a delta layer was investigated through the development of the first p-channel boron delta doped FET, which may offer advantages for submicron VLSI technology.\ud

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