Ayana Bhaduri - Academia.edu (original) (raw)

Papers by Ayana Bhaduri

Applied Surface Science, 2012

We have probed the dopant activity of silicon B-doped by Gas Immersion Laser Doping (GILD). Here,... more We have probed the dopant activity of silicon B-doped by Gas Immersion Laser Doping (GILD). Here, we report on the comparison of optical, electrical and structural properties of Si:B, over a wide concentration range, up to 1.5 × 10 21 cm −3 by steps of 1.5 × 10 19 cm −3. Data obtained by reflectance FTIR spectroscopy are used within a Drude model to extract concentration, thickness and mobility. Resulting carrier concentration and conductivity are checked with 4-point probe electrical and X-ray diffraction measurements. FTIR proved to be very sensitive to the dopant distribution inside the layer, despite its thinness. It clearly reveals a moderate dopant accumulation at the interfaces.

Applied Surface Science, Sep 1, 2012

We have probed the dopant activity of silicon B-doped by Gas Immersion Laser Doping (GILD). Here,... more We have probed the dopant activity of silicon B-doped by Gas Immersion Laser Doping (GILD). Here, we report on the comparison of optical, electrical and structural properties of Si:B, over a wide concentration range, up to 1.5 × 10 21 cm −3 by steps of 1.5 × 10 19 cm −3. Data obtained by reflectance FTIR spectroscopy are used within a Drude model to extract concentration, thickness and mobility. Resulting carrier concentration and conductivity are checked with 4-point probe electrical and X-ray diffraction measurements. FTIR proved to be very sensitive to the dopant distribution inside the layer, despite its thinness. It clearly reveals a moderate dopant accumulation at the interfaces.

Diamond and Related Materials, May 1, 2023

International journal of innovative research in physics, Feb 1, 2020

Graphene has attracted the scientific research community due to its unique two-dimensional struct... more Graphene has attracted the scientific research community due to its unique two-dimensional structure, high conductivity, large surface area, superior charge carrier mobility, superior thermal and mechanical properties etc. To obtain graphene by chemical route, graphite oxide (GO) is used as a medium which is obtained from graphite. There is large amount of hydroxyl, carboxyl, carbonyl, epoxide etc. functional groups attached onto the basal or edge plane of GO making it strongly hydrophilic and easily exfoliated in water. Further reduction of GO get rids of unwanted accessory functional groups results in formation of reduced graphene oxide (r-GO) having desired properties. Further its properties can be manipulated by synthesis of graphene/r-GO-metal/metal oxide composites according to the applications to be drawn. These composites can be used in various applications, such as, in energy storage devices like anode materials in lithium ion batteries (LIBs), supercapacitors, photocatalysts, sensors, removal of organic pollutants etc. In the present study, Graphene Oxide-ZnO composites are synthesised by a simple chemical precipitation method. Further the structural characterizations of the samples prepared are done by X-Ray Diffraction (XRD), UV-Visible Spectrophotometry, Fourier Transform Infrared Spectroscopy and Raman spectroscopy.

Journal of Applied Physics, Sep 15, 2008

In recent times, methylammonium lead chloride (CH 3 NH 3 PbCl 3) perovskites have great significa... more In recent times, methylammonium lead chloride (CH 3 NH 3 PbCl 3) perovskites have great significance as the optoelectronic material. Besides all the promising advantages, there are some problems which need to be resolved, one of such problem is to synthesize well-crystalline, highly homogeneous and the lessdefective surface of the perovskites by reducing the synthesis complexity. In this continual search of better properties, we have synthesized of CH 3 NH 3 PbCl 3 film by replacing traditional halide source of lead with a non-halide source of lead. We have also analysed their structural, morphological and optical properties of the film using XRD, FEG-SEM and DRS UV-Vis spectroscopy techniques. The detailed study confirms the cubic structure of the as-prepared film without any contamination. Surface morphology shows the formation of homogeneous spherical particles with an average size of 0.165 μm. DRS UV-Vis data shows a wide bandgap of 3.7 eV and due to that high transparency in the visible region of light. These outcomes open up the door for CH 3 NH 3 PbCl 3 film as a vital transparent conductor.

HAL (Le Centre pour la Communication Scientifique Directe), 2006

The highly precise spin-polarized density functional approach is utilized to study the structural... more The highly precise spin-polarized density functional approach is utilized to study the structural properties, chemical bonding, mechanical and optoelectronic properties of the cubic Y 2 M 2 O 7 (M = Ti, V and Nb) pyrochlores. The calculated structural parameters and geometries are consistent with experimental results. Electronic charge density explains that the nature of the bond between Y and M is covalent, whereas Ti-O, V-O and Nb-O bonds are ionic. Mechanical properties of these compounds demonstrate that Y 2 Nb 2 O 7 and Y 2 V 2 O 7 are ductile, whereas Y 2 Ti 2 O 7 is brittle in nature. The electronic band structures confirm the semiconducting nature for all the three materials with band gaps 2.8 eV, 0.2 eV, and 0.4 eV for Y 2 Ti 2 O 7 , Y 2 V 2 O 7 and Y 2 Nb 2 O 7 , respectively. Optical properties are calculated for the optically active compounds, which show that Y 2 Ti 2 O 7 and Y 2 V 2 O 7 are highly dielectric materials and are optically active in the visible and infrared regions of the electromagnetic spectrum.

Springer Proceedings in Materials

ChemBioEng Reviews

Manganese oxide nanoparticles with different crystal phases, morphologies, and structural diversi... more Manganese oxide nanoparticles with different crystal phases, morphologies, and structural diversity along with their exceptional properties like high specific surface area, a high fraction of surface atoms, non‐toxic nature, and excellent redox properties are drawing attention for various applications in storage science, especially in the batteries, super‐capacitors, energy conversion, and the environmental catalysis field. Precise control of particle size, morphology, surface area, Mnx+ oxidation state, etc. is the utmost important aspect to explore their application to the full potential. Here, the emphasis is on the recent trends in manganese oxide research – structure, synthesis, and applications. The structure of numerous crystalline phases of manganese oxide nanoparticles are summerized and several facile chemical synthesis processes to achieve the desired crystalline/amorphous structure are discoursed. Temperature and different synthesis conditions dependent phase transformat...

Diamond and Related Materials

Materials Chemistry and Physics

Environmental Science and Pollution Research

NATIONAL CONFERENCE ON PHYSICS AND CHEMISTRY OF MATERIALS: NCPCM2020, 2021

A series of ZnO-Graphene nanocomposites were synthesized by a simple and low-cost chemical coprec... more A series of ZnO-Graphene nanocomposites were synthesized by a simple and low-cost chemical coprecipitation method. GO was synthesized by using modified Hummers method. Zinc salt and graphene oxide (GO) of different mass ratios (3:1, 3:2 and 3:3 GO to Zn) were used as precursors in de-ionized water. Further the structural characterizations of the prepared samples were done by X-Ray Diffraction (XRD), UV-Visible Spectrophotometry, Fourier Transform Infrared Spectroscopy and Raman spectroscopy. FTIR studies confirmed the formation of graphene oxide with different oxygen containing functional groups. Raman studies confirmed that the samples have characteristic Raman modes D band, G band and 2D band in the range of 1340-1358 cm-1 , 1577-1583 cm-1 , and 2717-2722 cm-1 respectively. The XRD analysis has revealed that the synthesized ZnO-graphene nanocomposites have the typical peaks at ~26° and ~43°of graphene. UV-vis spectrum studies showed a slight increase in the energy band-gaps of ZnO-Graphene nanocomposites calculated by using Tauc plot.

AIP Conference Proceedings, 2019

Cupric Oxide (CuO), is an inexpensive and non-toxic p-type semiconductor material with a monoclin... more Cupric Oxide (CuO), is an inexpensive and non-toxic p-type semiconductor material with a monoclinic crystal structure having indirect band gap (Eg) 1.2 eV-1.9 eV. In this study, co-precipitation method has been employed to synthesize CuO nanoparticles. The samples were calcinated at 200 0 C or 400 0 C for decomposition of hydroxides to oxide. The XRD pattern of the CuO nanoparticles annealed at 400°C exhibited well defined peaks and are consistent with the standard values showing monoclinic structure of CuO with particle size in the range around 10 nm-12 nm and 14 nm-17 nm for slighty different precursor materials both samples annealed at 200°C. The nanoparticles size got aggregated when they are annealed at 400°C. This may be attributed to the agglomeration of the particles at high temperature. Hereby we are emphasizing the fact that the interest on old semiconductor like copper oxide still remains at a time when many new semiconductors such as the perovskites and organic semiconductors are being studied for PV applications is mainly due to sustainability. Both copper and oxygen are abundant elements like silicon and thus there can be no supply concern in the long run.

Solar Energy Materials and Solar Cells, 2010

Amorphous silicon-germanium (a-Si 1 À x Ge x :H) alloy thin films were studied over a wide range ... more Amorphous silicon-germanium (a-Si 1 À x Ge x :H) alloy thin films were studied over a wide range of Ge content (x ¼0-1.00) grown by radio frequency plasma CVD (rf PECVD) technique with variation of different deposition parameters such as H 2 dilution, rf power and square wave pulse modulation (SWPM) of rf amplitude. Structural properties like microstructure factor (R n) and AFM surface roughness (R RMS) were correlated with the transport properties such as mobility-lifetime product (mt) and ambipolar diffusion length (L d) of these films. Near the middle composition range (x¼ 0.32-0.70), the R n in these films varies between 0.20 and 0.42 and L d ranges between 50 and 60 nm. Films deposited near the pure silicon and pure germanium ends have improved structural and transport properties. By SWPM method we have been able to significantly lower the R n value of the a-Si 1 À x Ge x :H films to 0.15 with x ¼0.40-0.45 resulting in L d ¼ 100 nm and mt¼1.0 Â 10 À 6 cm 2 V À 1 .

Solar Energy Materials and Solar Cells, 2009

Microstructures in silicon germanium thin films deposited by pulsed rf plasma CVD have been studi... more Microstructures in silicon germanium thin films deposited by pulsed rf plasma CVD have been studied with the help of small-angle X-ray scattering (SAXS) and high-resolution transmission electron microscopy (HRTEM). With lowering of the pulse duty cycle the size of the particles incorporated in the films from the plasma decreases. However, the particles become more symmetric in shape and crystalline in

Semiconductor Science and Technology, 2012

ABSTRACT We deposited polycrystalline silicon (poly-Si) thin films on commercial float glass by c... more ABSTRACT We deposited polycrystalline silicon (poly-Si) thin films on commercial float glass by chemical vapour deposition from trichlorosilane at temperatures between 735 and 870 °C. The structural properties of the films were evaluated by means of scanning electron microscopy, x-ray diffraction, atomic force microscopy, reflectance in the ultraviolet region and Raman spectroscopy. The electrical characterization involved measurements of dark conductivity and photoconductivity as a function of temperature, Hall effect, ambipolar diffusion length from the steady-state photocarrier grating technique and density of defects by means of modulated photoconductivity. By using boron tribromide as a doping agent, degrees of doping ranging from intrinsic to clearly p-doped were obtained. The process, the reactants and the substrate used are of low cost, and proved to be adequate for direct poly-Si deposition, giving films of good structural and electrical properties.

physica status solidi (c), 2010

ABSTRACT We have regulated the number density and the size of the fine particles/clusters called ... more ABSTRACT We have regulated the number density and the size of the fine particles/clusters called nanoparticles into the a-SiGe:H films deposited from silane and germane diluted in hydrogen by applying a square wave pulse modulations (SWPM) of the rf (13.56 MHz) amplitude in plasma enhanced chemical vapor deposition (PECVD). The plasma “on” time Ton and “off” time Toff were controlled over a wide range from 300 μsec to 30 msec. Growth rate (r) of the number density (Nr) of the particles of size r shows a lognormal dependence on r. Tendency towards formation of nanocrystallites was observed on reducing the Ton. Ge content within nanocrystallites was found to increase with decrease in nanocrystallites size. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

physica status solidi (c), 2010

Abstract Formation of nanocrystallites in the amorphous silicon carbide thin films deposited from... more Abstract Formation of nanocrystallites in the amorphous silicon carbide thin films deposited from silane methane mixture diluted in argon by plasma enhanced CVD has been studied under different levels of rf power density and Ar dilution. Systematic transformations ...

Applied Surface Science, 2012

We have probed the dopant activity of silicon B-doped by Gas Immersion Laser Doping (GILD). Here,... more We have probed the dopant activity of silicon B-doped by Gas Immersion Laser Doping (GILD). Here, we report on the comparison of optical, electrical and structural properties of Si:B, over a wide concentration range, up to 1.5 × 10 21 cm −3 by steps of 1.5 × 10 19 cm −3. Data obtained by reflectance FTIR spectroscopy are used within a Drude model to extract concentration, thickness and mobility. Resulting carrier concentration and conductivity are checked with 4-point probe electrical and X-ray diffraction measurements. FTIR proved to be very sensitive to the dopant distribution inside the layer, despite its thinness. It clearly reveals a moderate dopant accumulation at the interfaces.

Applied Surface Science, Sep 1, 2012

We have probed the dopant activity of silicon B-doped by Gas Immersion Laser Doping (GILD). Here,... more We have probed the dopant activity of silicon B-doped by Gas Immersion Laser Doping (GILD). Here, we report on the comparison of optical, electrical and structural properties of Si:B, over a wide concentration range, up to 1.5 × 10 21 cm −3 by steps of 1.5 × 10 19 cm −3. Data obtained by reflectance FTIR spectroscopy are used within a Drude model to extract concentration, thickness and mobility. Resulting carrier concentration and conductivity are checked with 4-point probe electrical and X-ray diffraction measurements. FTIR proved to be very sensitive to the dopant distribution inside the layer, despite its thinness. It clearly reveals a moderate dopant accumulation at the interfaces.

Diamond and Related Materials, May 1, 2023

International journal of innovative research in physics, Feb 1, 2020

Graphene has attracted the scientific research community due to its unique two-dimensional struct... more Graphene has attracted the scientific research community due to its unique two-dimensional structure, high conductivity, large surface area, superior charge carrier mobility, superior thermal and mechanical properties etc. To obtain graphene by chemical route, graphite oxide (GO) is used as a medium which is obtained from graphite. There is large amount of hydroxyl, carboxyl, carbonyl, epoxide etc. functional groups attached onto the basal or edge plane of GO making it strongly hydrophilic and easily exfoliated in water. Further reduction of GO get rids of unwanted accessory functional groups results in formation of reduced graphene oxide (r-GO) having desired properties. Further its properties can be manipulated by synthesis of graphene/r-GO-metal/metal oxide composites according to the applications to be drawn. These composites can be used in various applications, such as, in energy storage devices like anode materials in lithium ion batteries (LIBs), supercapacitors, photocatalysts, sensors, removal of organic pollutants etc. In the present study, Graphene Oxide-ZnO composites are synthesised by a simple chemical precipitation method. Further the structural characterizations of the samples prepared are done by X-Ray Diffraction (XRD), UV-Visible Spectrophotometry, Fourier Transform Infrared Spectroscopy and Raman spectroscopy.

Journal of Applied Physics, Sep 15, 2008

In recent times, methylammonium lead chloride (CH 3 NH 3 PbCl 3) perovskites have great significa... more In recent times, methylammonium lead chloride (CH 3 NH 3 PbCl 3) perovskites have great significance as the optoelectronic material. Besides all the promising advantages, there are some problems which need to be resolved, one of such problem is to synthesize well-crystalline, highly homogeneous and the lessdefective surface of the perovskites by reducing the synthesis complexity. In this continual search of better properties, we have synthesized of CH 3 NH 3 PbCl 3 film by replacing traditional halide source of lead with a non-halide source of lead. We have also analysed their structural, morphological and optical properties of the film using XRD, FEG-SEM and DRS UV-Vis spectroscopy techniques. The detailed study confirms the cubic structure of the as-prepared film without any contamination. Surface morphology shows the formation of homogeneous spherical particles with an average size of 0.165 μm. DRS UV-Vis data shows a wide bandgap of 3.7 eV and due to that high transparency in the visible region of light. These outcomes open up the door for CH 3 NH 3 PbCl 3 film as a vital transparent conductor.

HAL (Le Centre pour la Communication Scientifique Directe), 2006

The highly precise spin-polarized density functional approach is utilized to study the structural... more The highly precise spin-polarized density functional approach is utilized to study the structural properties, chemical bonding, mechanical and optoelectronic properties of the cubic Y 2 M 2 O 7 (M = Ti, V and Nb) pyrochlores. The calculated structural parameters and geometries are consistent with experimental results. Electronic charge density explains that the nature of the bond between Y and M is covalent, whereas Ti-O, V-O and Nb-O bonds are ionic. Mechanical properties of these compounds demonstrate that Y 2 Nb 2 O 7 and Y 2 V 2 O 7 are ductile, whereas Y 2 Ti 2 O 7 is brittle in nature. The electronic band structures confirm the semiconducting nature for all the three materials with band gaps 2.8 eV, 0.2 eV, and 0.4 eV for Y 2 Ti 2 O 7 , Y 2 V 2 O 7 and Y 2 Nb 2 O 7 , respectively. Optical properties are calculated for the optically active compounds, which show that Y 2 Ti 2 O 7 and Y 2 V 2 O 7 are highly dielectric materials and are optically active in the visible and infrared regions of the electromagnetic spectrum.

Springer Proceedings in Materials

ChemBioEng Reviews

Manganese oxide nanoparticles with different crystal phases, morphologies, and structural diversi... more Manganese oxide nanoparticles with different crystal phases, morphologies, and structural diversity along with their exceptional properties like high specific surface area, a high fraction of surface atoms, non‐toxic nature, and excellent redox properties are drawing attention for various applications in storage science, especially in the batteries, super‐capacitors, energy conversion, and the environmental catalysis field. Precise control of particle size, morphology, surface area, Mnx+ oxidation state, etc. is the utmost important aspect to explore their application to the full potential. Here, the emphasis is on the recent trends in manganese oxide research – structure, synthesis, and applications. The structure of numerous crystalline phases of manganese oxide nanoparticles are summerized and several facile chemical synthesis processes to achieve the desired crystalline/amorphous structure are discoursed. Temperature and different synthesis conditions dependent phase transformat...

Diamond and Related Materials

Materials Chemistry and Physics

Environmental Science and Pollution Research

NATIONAL CONFERENCE ON PHYSICS AND CHEMISTRY OF MATERIALS: NCPCM2020, 2021

A series of ZnO-Graphene nanocomposites were synthesized by a simple and low-cost chemical coprec... more A series of ZnO-Graphene nanocomposites were synthesized by a simple and low-cost chemical coprecipitation method. GO was synthesized by using modified Hummers method. Zinc salt and graphene oxide (GO) of different mass ratios (3:1, 3:2 and 3:3 GO to Zn) were used as precursors in de-ionized water. Further the structural characterizations of the prepared samples were done by X-Ray Diffraction (XRD), UV-Visible Spectrophotometry, Fourier Transform Infrared Spectroscopy and Raman spectroscopy. FTIR studies confirmed the formation of graphene oxide with different oxygen containing functional groups. Raman studies confirmed that the samples have characteristic Raman modes D band, G band and 2D band in the range of 1340-1358 cm-1 , 1577-1583 cm-1 , and 2717-2722 cm-1 respectively. The XRD analysis has revealed that the synthesized ZnO-graphene nanocomposites have the typical peaks at ~26° and ~43°of graphene. UV-vis spectrum studies showed a slight increase in the energy band-gaps of ZnO-Graphene nanocomposites calculated by using Tauc plot.

AIP Conference Proceedings, 2019

Cupric Oxide (CuO), is an inexpensive and non-toxic p-type semiconductor material with a monoclin... more Cupric Oxide (CuO), is an inexpensive and non-toxic p-type semiconductor material with a monoclinic crystal structure having indirect band gap (Eg) 1.2 eV-1.9 eV. In this study, co-precipitation method has been employed to synthesize CuO nanoparticles. The samples were calcinated at 200 0 C or 400 0 C for decomposition of hydroxides to oxide. The XRD pattern of the CuO nanoparticles annealed at 400°C exhibited well defined peaks and are consistent with the standard values showing monoclinic structure of CuO with particle size in the range around 10 nm-12 nm and 14 nm-17 nm for slighty different precursor materials both samples annealed at 200°C. The nanoparticles size got aggregated when they are annealed at 400°C. This may be attributed to the agglomeration of the particles at high temperature. Hereby we are emphasizing the fact that the interest on old semiconductor like copper oxide still remains at a time when many new semiconductors such as the perovskites and organic semiconductors are being studied for PV applications is mainly due to sustainability. Both copper and oxygen are abundant elements like silicon and thus there can be no supply concern in the long run.

Solar Energy Materials and Solar Cells, 2010

Amorphous silicon-germanium (a-Si 1 À x Ge x :H) alloy thin films were studied over a wide range ... more Amorphous silicon-germanium (a-Si 1 À x Ge x :H) alloy thin films were studied over a wide range of Ge content (x ¼0-1.00) grown by radio frequency plasma CVD (rf PECVD) technique with variation of different deposition parameters such as H 2 dilution, rf power and square wave pulse modulation (SWPM) of rf amplitude. Structural properties like microstructure factor (R n) and AFM surface roughness (R RMS) were correlated with the transport properties such as mobility-lifetime product (mt) and ambipolar diffusion length (L d) of these films. Near the middle composition range (x¼ 0.32-0.70), the R n in these films varies between 0.20 and 0.42 and L d ranges between 50 and 60 nm. Films deposited near the pure silicon and pure germanium ends have improved structural and transport properties. By SWPM method we have been able to significantly lower the R n value of the a-Si 1 À x Ge x :H films to 0.15 with x ¼0.40-0.45 resulting in L d ¼ 100 nm and mt¼1.0 Â 10 À 6 cm 2 V À 1 .

Solar Energy Materials and Solar Cells, 2009

Microstructures in silicon germanium thin films deposited by pulsed rf plasma CVD have been studi... more Microstructures in silicon germanium thin films deposited by pulsed rf plasma CVD have been studied with the help of small-angle X-ray scattering (SAXS) and high-resolution transmission electron microscopy (HRTEM). With lowering of the pulse duty cycle the size of the particles incorporated in the films from the plasma decreases. However, the particles become more symmetric in shape and crystalline in

Semiconductor Science and Technology, 2012

ABSTRACT We deposited polycrystalline silicon (poly-Si) thin films on commercial float glass by c... more ABSTRACT We deposited polycrystalline silicon (poly-Si) thin films on commercial float glass by chemical vapour deposition from trichlorosilane at temperatures between 735 and 870 °C. The structural properties of the films were evaluated by means of scanning electron microscopy, x-ray diffraction, atomic force microscopy, reflectance in the ultraviolet region and Raman spectroscopy. The electrical characterization involved measurements of dark conductivity and photoconductivity as a function of temperature, Hall effect, ambipolar diffusion length from the steady-state photocarrier grating technique and density of defects by means of modulated photoconductivity. By using boron tribromide as a doping agent, degrees of doping ranging from intrinsic to clearly p-doped were obtained. The process, the reactants and the substrate used are of low cost, and proved to be adequate for direct poly-Si deposition, giving films of good structural and electrical properties.

physica status solidi (c), 2010

ABSTRACT We have regulated the number density and the size of the fine particles/clusters called ... more ABSTRACT We have regulated the number density and the size of the fine particles/clusters called nanoparticles into the a-SiGe:H films deposited from silane and germane diluted in hydrogen by applying a square wave pulse modulations (SWPM) of the rf (13.56 MHz) amplitude in plasma enhanced chemical vapor deposition (PECVD). The plasma “on” time Ton and “off” time Toff were controlled over a wide range from 300 μsec to 30 msec. Growth rate (r) of the number density (Nr) of the particles of size r shows a lognormal dependence on r. Tendency towards formation of nanocrystallites was observed on reducing the Ton. Ge content within nanocrystallites was found to increase with decrease in nanocrystallites size. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

physica status solidi (c), 2010

Abstract Formation of nanocrystallites in the amorphous silicon carbide thin films deposited from... more Abstract Formation of nanocrystallites in the amorphous silicon carbide thin films deposited from silane methane mixture diluted in argon by plasma enhanced CVD has been studied under different levels of rf power density and Ar dilution. Systematic transformations ...