Alam Abedini - Academia.edu (original) (raw)

Papers by Alam Abedini

Abstract: ZnS and CdS nanoparticles were prepared by a simple microwave irradiation method under ... more Abstract: ZnS and CdS nanoparticles were prepared by a simple microwave irradiation method under mild conditions. The obtained nanoparticles were characterized by XRD, TEM and EDX. The results indicated that high purity of nanosized ZnS and CdS was successfully obtained with cubic and hexagonal crystalline structures, respectively. The band gap energies of ZnS and CdS nanoparticles were estimated using UV-visible absorption spectra to be about 4.22 and 2.64 eV, respectively. Photocatalytic degradation of methylene blue was carried out using physical mixtures of ZnS and CdS nanoparticles under a 500-W halogen lamp of visible light irradiation. The residual concentration of methylene blue solution was monitored using UV-visible absorption spectrometry. From the study of the variation in composition of ZnS:CdS, a composition of 1:4 (by weight) was found to be very efficient for degradation of methylene blue. In this case the degradation efficiency of the photocatalyst nanoparticles aft...

Colloidal Fe3O4 nanoparticles were synthesized using a gamma-radiolysis method in an aqueous solu... more Colloidal Fe3O4 nanoparticles were synthesized using a gamma-radiolysis method in an aqueous solution containing iron chloride in presence of polyvinyl alcohol and isopropanol as colloidal stabilizer and hydroxyl radical scavenger, respectively. Gamma irradiation was carried out in a 60Co gamma source chamber at different absorbed doses. Increasing the radiation dose above a certain critical dose (100 kGy) leads to particle agglomeration enhancement, and this can influence the structure and crystallinity, and consequently the magnetic properties of the resultant particles. The optimal condition for formation of Fe3O4 nanoparticles with a uniform and narrow size distribution occurred at a dose of 100 kGy, as confirmed by X-ray diffractometry and transmission electron microscopy. A vibrating sample magnetometry study showed that, when radiation dose increased, the saturation and remanence magnetization decreased, whereas the coercivity and the remanence ratio increased. This magnetic ...

Colloidal Cu@CuAlO 2-Al 2 O 3 bimetallic nanoparticles were prepared by a gamma irradiation metho... more Colloidal Cu@CuAlO 2-Al 2 O 3 bimetallic nanoparticles were prepared by a gamma irradiation method in an aqueous system in the presence of polyvinyl pyrrolidone (PVP) and isopropanol respectively as a colloidal stabilizer and scavenger of hydrogen and hydroxyl radicals. The gamma irradiation was carried out in a 60 Co gamma source chamber with different doses up to 120 kGy. The formation of Cu@CuAlO 2-Al 2 O 3 nanoparticles was observed initially by the change in color of the colloidal samples from colorless to brown. Fourier transform infrared spectroscopy (FTIR) confirmed the presence of bonds between polymer chains and the metal surface at all radiation doses. Results of transmission electron microscopy (TEM), energy dispersive X-ray spectrometry (EDX), and X-ray diffraction (XRD) showed that Cu@CuAlO 2-Al 2 O 3 nanoparticles are in a core-shell structure. By controlling the absorbed dose and precursor concentration, nanoclusters with different particle sizes were obtained. The average particle diameter increased with increased precursor concentration and decreased with increased dose. This is due to the competition between nucleation, growth, and aggregation processes in the formation of nanoclusters during irradiation.

The last two decades have seen remarkable progress in nanoscience and nanotechnology particularly... more The last two decades have seen remarkable progress in nanoscience and nanotechnology particularly in the synthesis of metal nanomaterials, aiming at finding better materials that have desired physical and chemical properties from enhancement of the surface and quantum confinement effects. Intermetallic aluminides such as Al-Ni and Al-Cu bimetallic nanoparticles have attractive properties for examples low densities, high strength and stiffness at elevated temperatures, strong resistances to mechanical, corrosion, acids and alkalis, and outstanding catalytic activity. They are of significant for wide potential applications in pigments, catalysts, and absorbents for Al-Cu bimetallic nanoparticles and in turbine blades, automobile engines, aircraft,electricity generation, and anode electrode materials for Al-Ni bimetallic nanoparticles. Such impressive characteristics and applications of Al-Ni and Al-Cu bimetallic nanoparticles have led us to research their functional systems with the o...

Silicon, 2017

In this paper, the effect of channel width variation on performance of double lateral gate juncti... more In this paper, the effect of channel width variation on performance of double lateral gate junctionless transistors in the depletion and accumulation regimes is investigated. The characteristics of the device with various channel widths is comprehensively examined through analysis of on and off state current, threshold voltage (V th), transconductance (g m) and drain conductance (g D) variation in each operating regime. The carriers’ density distribution, electric field components and mobility are investigated through 3-D numerical simulations of the device to illustrate the variation of output characteristics. The results show that as the width decreases, the off-current (IOFF) decreases significantly as a result of better electrostatic control of the lateral gates over the channel. The on-current (ION) is also decreased mainly due to the doping-dependent mobility degradation.It is also indicated that between the flat-band and fully depleted (pinch off) variation of the majority carriers is the main parameter that modifies the characteristics of the device, while the mobility variation is recognized as the basic factor in the accumulation regime.

Plasmonics, 2017

There is increasing interest in tuning the physical properties of semiconductor nanostructures us... more There is increasing interest in tuning the physical properties of semiconductor nanostructures using metal nanoparticles. In this work, ZnO nanosphere covered with Ag nanoparticles were synthesized using gamma–radiation-assisted method. The amount of deposited Ag nanoparticles is controlled by changing irradiation dose in the range of 30–100 kGy in order to tune the semiconductor–metal interaction. The successful deposition of Ag on the ZnO nanoparticles is examined by analyzing the morphology, microstructure, optical, and magnetic properties of ZnO/Ag nanoparticles through field emission scanning electron (FESEM), microscopy X-ray diffraction spectra, UV-visible absorption, photoluminescence measurement, and vibrating sample magnetometer. FESEM and elemental mapping results confirmed that Ag nanoparticles have been concentrated at the surface of spherical ZnO particles. Moreover, formation of pure metallic Ag nanoparticles has been confirmed by XRD analysis. UV-visible absorption spectra of obtained ZnO/Ag showed two combined peaks, a weak peak at the shoulder around 360 nm corresponds to ZnO and a sharp absorption at 420 nm refers to spherical Ag nanoparticles. Obtained results from photoluminescence revealed that the near-band-edge emission and defect-related visible emission bands of ZnO could be enhanced dramatically at the same time by deposition of Ag nanoparticles, which was ascribed to localized surface plasmon–exciton coupling and surface plasmon scattering. Controlling the semiconductor and metal coupling effect is interesting because of its application in highly efficient optoelectronic devices and biosensor.

Journal of Alloys and Compounds, 2017

Hydrous Fe/Ni-based oxide components nanoparticles in core/shell structure were successfully synt... more Hydrous Fe/Ni-based oxide components nanoparticles in core/shell structure were successfully synthesized by radiolytic reduction method. Structural analysis confirmed the formation of double-layered nanoparticles with iron oxide core, which are more easily reducible by gamma radiation rather than Ni ions, and (Fe, Ni)OOH shell at lower irradiation dose. At high irradiation doses, the formation of triple-layered nanoparticles with the core of iron oxide and the outer shell of nickel/nickel oxide and middle layer made of hydroxide of both kinds of metals were observed. The modification of core, shell and middle layer effectively influence on final structure which consequently affect on the magnetic and mechanical properties of the final products. By increasing radiation dose, the phase transition between super-paramagnetic to ferromagnetic has been observed. Moreover, the stiffness value increased by irradiation dose increasing. The phase transition can be explained by variation of Ni content at the surface of iron oxide core, while the increase in the stiffness of the final product is mainly due to the increasing in Ni content of final products.

Nanoscale research letters, 2016

This paper focuses on the recent advances on radiolysis-assisted shape-controlled synthesis of no... more This paper focuses on the recent advances on radiolysis-assisted shape-controlled synthesis of noble metal nanostructures. The techniques and protocols for producing desirable shapes of noble metal nanoparticles are discussed through introducing the critical parameters which can influence the nucleation and growth mechanisms. Nucleation rate plays a vital role on the crystallinity of seeds while growth rate of different seeds' facets determines the final shape of resultant nanoparticles. Nucleation and growth rate both can be altered with factors such as absorbed dose, capping agents, and experimental environment condition to control the final shape. Remarkable physical and chemical properties of synthesized noble metal nanoparticles by controlled morphology have been systematically evaluated to fully explore their applications.

Journal of Radioanalytical and Nuclear Chemistry, 2015

ABSTRACT In this work, luminescent triangular silver nanoparticles were synthesized by radiolytic... more ABSTRACT In this work, luminescent triangular silver nanoparticles were synthesized by radiolytic reduction method. The results showed that by variation of irradiation dose, morphology of silver nanoparticles can be converted from spherical to triangular. These shape variations mainly arise from competition between adsorption rate of polymer chains on (111) facets and reduction rate of the Ag+ ions along (110) facets during increasing dose. Furthermore, the dramatically enhanced photoluminescence spectra were observed from triangular Ag nanoparticles. This unusual behavior can be explained by excitation of dipolar and quadrupolar resonance in triangular nanoparticles which increase the electric fields at the surface.

Kerntechnik, 2013

ABSTRACT Cu – Al bimetallic nanoparticles were synthesized by gamma irradiation technique in aque... more ABSTRACT Cu – Al bimetallic nanoparticles were synthesized by gamma irradiation technique in aqueous solutions containing metal chlorides as precursors, polyvinyl alcohol (PVA) as a capping agent, isopropanol as a radical scavenger, and distilled water as a solvent. The Cu – Al bimetallic nanoparticles were characterized by transmission electron microscopy (TEM), UV-visible absorption spectrometry, powder X-ray diffractometer (XRD), and Energy-dispersive X-ray spectroscopy (EDX). The TEM, XRD, EDX, and absorption analyses confirmed the formation of core-shell structure of Cu – Al bimetallic nanoparticles at lower Cu2+/Al3+ mole ratio, and the formation of Cu – Al alloy nanoparticles at higher Cu2+/Al3+ mole ratio. The TEM analysis for particle size and size distribution revealed that the average particle size of Cu – Al bimetallic nanoparticles decreased with the increase of absorbed dose. It may be explained due to the competition between nucleation and aggregation processes in the formation of metallic nanoparticles under irradiation.

Journal of Radioanalytical and Nuclear Chemistry, 2012

Your article is protected by copyright and all rights are held exclusively by Akadémiai Kiadó, Bu... more Your article is protected by copyright and all rights are held exclusively by Akadémiai Kiadó, Budapest, Hungary. This e-offprint is for personal use only and shall not be selfarchived in electronic repositories. If you wish to self-archive your work, please use the accepted author's version for posting to your own website or your institution's repository. You may further deposit the accepted author's version on a funder's repository at a funder's request, provided it is not made publicly available until 12 months after publication.

In this letter, we investigate the fabrication of Double gate and Single gate Junctionless silico... more In this letter, we investigate the fabrication of Double gate and Single gate Junctionless silicon nanowire transistor using silicon nanowire patterned on lightly doped (10 5 cm-3) p-type Silicon on insulator wafer fabricated by Atomic force microscopy nanolithography technique. Local anodic oxidation followed by two wet etching steps, Potassium hydroxide etching for Silicon removal and Hydrofluoric acid etching for oxide removal, were implemented to reach the structures. Writing speed and applied tip voltage were held in 0.6 µm/s and 8 volt respectively for Cr/Pt tip. Scan speed was held in 1.0µm/s. The etching processes were elaborately performed and optimized by 30%wt. Potassium hydroxide + 10%vol. Isopropyl alcohol in appropriate time, temperature and humidity. The structure is a gated resistor turned off based on a pinch-off effect principle, when essential positive gate voltage is applied. Negative gate voltage is unable to make significant effect on drain current to drive the device into accumulation mode.

We present the fabrication, electrical characteristics, and effect of lateral gates in a junction... more We present the fabrication, electrical characteristics, and effect of lateral gates in a junctionless silicon nanowire transistor. The transistor uses silicon nanowire on silicon-on-insulator wafer fabricated with an atomic force microscope nanolithography technique. Using AFM nanolithography allows us to make a chemical contrast between locally oxidized part of the surface and unexposed surface. This chemical contrast affects as a mask and the active part of the device is finally obtained after two step etching. The structure is uniformly low-doped for source, drain, channel, and the lateral gates regions, and confirms the behavior of junctionless nanowire transistors. The output current is controlled by channel doping and mobility of carriers instead of gate capacitance and it basically uses bulk conduction instead of surface channel conduction. The fabricated device exhibits an on-off ratio of 2×10 6 and a subthreshold swing of 160 mV/decade.

Journal of Radioanalytical and Nuclear Chemistry, 2015

ABSTRACT Hollow Fe x Ni(1−x)OOH nanospheres with average diameter and shell thickness of about 15... more ABSTRACT Hollow Fe x Ni(1−x)OOH nanospheres with average diameter and shell thickness of about 15 and 5 nm were successfully synthesized for the first time through the radiation induced self-template method. The fast outward diffusion of Fe(III) ions due to Kirkendall effect between the core (FeOOH) and the shell (Fe x Ni(1−x)OOH) is the main reason for appearing the hollow nanoparticles. The results showed that a passive layer of Fe(III) species was formed at core and shell interface and Ni(II) ions play an important role in hollowing process of nanoparticles.

Beilstein journal of nanotechnology, 2012

A double-lateral-gate p-type junctionless transistor is fabricated on a low-doped (10(15)) silico... more A double-lateral-gate p-type junctionless transistor is fabricated on a low-doped (10(15)) silicon-on-insulator wafer by a lithography technique based on scanning probe microscopy and two steps of wet chemical etching. The experimental transfer characteristics are obtained and compared with the numerical characteristics of the device. The simulation results are used to investigate the pinch-off mechanism, from the flat band to the off state. The study is based on the variation of the carrier density and the electric-field components. The device is a pinch-off transistor, which is normally in the on state and is driven into the off state by the application of a positive gate voltage. We demonstrate that the depletion starts from the bottom corner of the channel facing the gates and expands toward the center and top of the channel. Redistribution of the carriers due to the electric field emanating from the gates creates an electric field perpendicular to the current, toward the bottom...

Journal of Materials Science

The structural changes of radiolytically prepared aluminium-copper (Al-Cu) bimetallic nanoparticl... more The structural changes of radiolytically prepared aluminium-copper (Al-Cu) bimetallic nanoparticles by adjusting the precursors' mole ratio and gamma radiation dose were investigated by transmission electron microscopy, field emission scanning electron microscopy/ energy dispersive spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy (FTIR), and X-band continuous wave electron paramagnetic resonance (EPR). The EPR spectrum was also analysed through the simulation of the powder-like EPR spectra. The results note that in prepared samples with higher Al contents, formation of coreshell structure is dominant, whereas in Cu-rich samples, the final structures are primarily in alloy and oxide forms. According to the analysis of data obtained from X-ray diffraction, FTIR, and EPR, we found that the unpaired electron of the Cu 2? ion in various phases play the main role in structural phase transformation of Al-Cu nanoparticles. Additionally, based on the information extracted from simulated EPR peaks of Cu-Cu, the diameter of the Cu core in core-shell structures was obtained. We showed that by increasing the gamma radiation dose from 80 to 120 kGy, the overall size of nanoparticles decreases from 9.47 to 3.75 nm, but the contribution of copper core increases from 11 to 22 % of overall particle size.

Abstract: ZnS and CdS nanoparticles were prepared by a simple microwave irradiation method under ... more Abstract: ZnS and CdS nanoparticles were prepared by a simple microwave irradiation method under mild conditions. The obtained nanoparticles were characterized by XRD, TEM and EDX. The results indicated that high purity of nanosized ZnS and CdS was successfully obtained with cubic and hexagonal crystalline structures, respectively. The band gap energies of ZnS and CdS nanoparticles were estimated using UV-visible absorption spectra to be about 4.22 and 2.64 eV, respectively. Photocatalytic degradation of methylene blue was carried out using physical mixtures of ZnS and CdS nanoparticles under a 500-W halogen lamp of visible light irradiation. The residual concentration of methylene blue solution was monitored using UV-visible absorption spectrometry. From the study of the variation in composition of ZnS:CdS, a composition of 1:4 (by weight) was found to be very efficient for degradation of methylene blue. In this case the degradation efficiency of the photocatalyst nanoparticles aft...

Colloidal Fe3O4 nanoparticles were synthesized using a gamma-radiolysis method in an aqueous solu... more Colloidal Fe3O4 nanoparticles were synthesized using a gamma-radiolysis method in an aqueous solution containing iron chloride in presence of polyvinyl alcohol and isopropanol as colloidal stabilizer and hydroxyl radical scavenger, respectively. Gamma irradiation was carried out in a 60Co gamma source chamber at different absorbed doses. Increasing the radiation dose above a certain critical dose (100 kGy) leads to particle agglomeration enhancement, and this can influence the structure and crystallinity, and consequently the magnetic properties of the resultant particles. The optimal condition for formation of Fe3O4 nanoparticles with a uniform and narrow size distribution occurred at a dose of 100 kGy, as confirmed by X-ray diffractometry and transmission electron microscopy. A vibrating sample magnetometry study showed that, when radiation dose increased, the saturation and remanence magnetization decreased, whereas the coercivity and the remanence ratio increased. This magnetic ...

Colloidal Cu@CuAlO 2-Al 2 O 3 bimetallic nanoparticles were prepared by a gamma irradiation metho... more Colloidal Cu@CuAlO 2-Al 2 O 3 bimetallic nanoparticles were prepared by a gamma irradiation method in an aqueous system in the presence of polyvinyl pyrrolidone (PVP) and isopropanol respectively as a colloidal stabilizer and scavenger of hydrogen and hydroxyl radicals. The gamma irradiation was carried out in a 60 Co gamma source chamber with different doses up to 120 kGy. The formation of Cu@CuAlO 2-Al 2 O 3 nanoparticles was observed initially by the change in color of the colloidal samples from colorless to brown. Fourier transform infrared spectroscopy (FTIR) confirmed the presence of bonds between polymer chains and the metal surface at all radiation doses. Results of transmission electron microscopy (TEM), energy dispersive X-ray spectrometry (EDX), and X-ray diffraction (XRD) showed that Cu@CuAlO 2-Al 2 O 3 nanoparticles are in a core-shell structure. By controlling the absorbed dose and precursor concentration, nanoclusters with different particle sizes were obtained. The average particle diameter increased with increased precursor concentration and decreased with increased dose. This is due to the competition between nucleation, growth, and aggregation processes in the formation of nanoclusters during irradiation.

The last two decades have seen remarkable progress in nanoscience and nanotechnology particularly... more The last two decades have seen remarkable progress in nanoscience and nanotechnology particularly in the synthesis of metal nanomaterials, aiming at finding better materials that have desired physical and chemical properties from enhancement of the surface and quantum confinement effects. Intermetallic aluminides such as Al-Ni and Al-Cu bimetallic nanoparticles have attractive properties for examples low densities, high strength and stiffness at elevated temperatures, strong resistances to mechanical, corrosion, acids and alkalis, and outstanding catalytic activity. They are of significant for wide potential applications in pigments, catalysts, and absorbents for Al-Cu bimetallic nanoparticles and in turbine blades, automobile engines, aircraft,electricity generation, and anode electrode materials for Al-Ni bimetallic nanoparticles. Such impressive characteristics and applications of Al-Ni and Al-Cu bimetallic nanoparticles have led us to research their functional systems with the o...

Silicon, 2017

In this paper, the effect of channel width variation on performance of double lateral gate juncti... more In this paper, the effect of channel width variation on performance of double lateral gate junctionless transistors in the depletion and accumulation regimes is investigated. The characteristics of the device with various channel widths is comprehensively examined through analysis of on and off state current, threshold voltage (V th), transconductance (g m) and drain conductance (g D) variation in each operating regime. The carriers’ density distribution, electric field components and mobility are investigated through 3-D numerical simulations of the device to illustrate the variation of output characteristics. The results show that as the width decreases, the off-current (IOFF) decreases significantly as a result of better electrostatic control of the lateral gates over the channel. The on-current (ION) is also decreased mainly due to the doping-dependent mobility degradation.It is also indicated that between the flat-band and fully depleted (pinch off) variation of the majority carriers is the main parameter that modifies the characteristics of the device, while the mobility variation is recognized as the basic factor in the accumulation regime.

Plasmonics, 2017

There is increasing interest in tuning the physical properties of semiconductor nanostructures us... more There is increasing interest in tuning the physical properties of semiconductor nanostructures using metal nanoparticles. In this work, ZnO nanosphere covered with Ag nanoparticles were synthesized using gamma–radiation-assisted method. The amount of deposited Ag nanoparticles is controlled by changing irradiation dose in the range of 30–100 kGy in order to tune the semiconductor–metal interaction. The successful deposition of Ag on the ZnO nanoparticles is examined by analyzing the morphology, microstructure, optical, and magnetic properties of ZnO/Ag nanoparticles through field emission scanning electron (FESEM), microscopy X-ray diffraction spectra, UV-visible absorption, photoluminescence measurement, and vibrating sample magnetometer. FESEM and elemental mapping results confirmed that Ag nanoparticles have been concentrated at the surface of spherical ZnO particles. Moreover, formation of pure metallic Ag nanoparticles has been confirmed by XRD analysis. UV-visible absorption spectra of obtained ZnO/Ag showed two combined peaks, a weak peak at the shoulder around 360 nm corresponds to ZnO and a sharp absorption at 420 nm refers to spherical Ag nanoparticles. Obtained results from photoluminescence revealed that the near-band-edge emission and defect-related visible emission bands of ZnO could be enhanced dramatically at the same time by deposition of Ag nanoparticles, which was ascribed to localized surface plasmon–exciton coupling and surface plasmon scattering. Controlling the semiconductor and metal coupling effect is interesting because of its application in highly efficient optoelectronic devices and biosensor.

Journal of Alloys and Compounds, 2017

Hydrous Fe/Ni-based oxide components nanoparticles in core/shell structure were successfully synt... more Hydrous Fe/Ni-based oxide components nanoparticles in core/shell structure were successfully synthesized by radiolytic reduction method. Structural analysis confirmed the formation of double-layered nanoparticles with iron oxide core, which are more easily reducible by gamma radiation rather than Ni ions, and (Fe, Ni)OOH shell at lower irradiation dose. At high irradiation doses, the formation of triple-layered nanoparticles with the core of iron oxide and the outer shell of nickel/nickel oxide and middle layer made of hydroxide of both kinds of metals were observed. The modification of core, shell and middle layer effectively influence on final structure which consequently affect on the magnetic and mechanical properties of the final products. By increasing radiation dose, the phase transition between super-paramagnetic to ferromagnetic has been observed. Moreover, the stiffness value increased by irradiation dose increasing. The phase transition can be explained by variation of Ni content at the surface of iron oxide core, while the increase in the stiffness of the final product is mainly due to the increasing in Ni content of final products.

Nanoscale research letters, 2016

This paper focuses on the recent advances on radiolysis-assisted shape-controlled synthesis of no... more This paper focuses on the recent advances on radiolysis-assisted shape-controlled synthesis of noble metal nanostructures. The techniques and protocols for producing desirable shapes of noble metal nanoparticles are discussed through introducing the critical parameters which can influence the nucleation and growth mechanisms. Nucleation rate plays a vital role on the crystallinity of seeds while growth rate of different seeds' facets determines the final shape of resultant nanoparticles. Nucleation and growth rate both can be altered with factors such as absorbed dose, capping agents, and experimental environment condition to control the final shape. Remarkable physical and chemical properties of synthesized noble metal nanoparticles by controlled morphology have been systematically evaluated to fully explore their applications.

Journal of Radioanalytical and Nuclear Chemistry, 2015

ABSTRACT In this work, luminescent triangular silver nanoparticles were synthesized by radiolytic... more ABSTRACT In this work, luminescent triangular silver nanoparticles were synthesized by radiolytic reduction method. The results showed that by variation of irradiation dose, morphology of silver nanoparticles can be converted from spherical to triangular. These shape variations mainly arise from competition between adsorption rate of polymer chains on (111) facets and reduction rate of the Ag+ ions along (110) facets during increasing dose. Furthermore, the dramatically enhanced photoluminescence spectra were observed from triangular Ag nanoparticles. This unusual behavior can be explained by excitation of dipolar and quadrupolar resonance in triangular nanoparticles which increase the electric fields at the surface.

Kerntechnik, 2013

ABSTRACT Cu – Al bimetallic nanoparticles were synthesized by gamma irradiation technique in aque... more ABSTRACT Cu – Al bimetallic nanoparticles were synthesized by gamma irradiation technique in aqueous solutions containing metal chlorides as precursors, polyvinyl alcohol (PVA) as a capping agent, isopropanol as a radical scavenger, and distilled water as a solvent. The Cu – Al bimetallic nanoparticles were characterized by transmission electron microscopy (TEM), UV-visible absorption spectrometry, powder X-ray diffractometer (XRD), and Energy-dispersive X-ray spectroscopy (EDX). The TEM, XRD, EDX, and absorption analyses confirmed the formation of core-shell structure of Cu – Al bimetallic nanoparticles at lower Cu2+/Al3+ mole ratio, and the formation of Cu – Al alloy nanoparticles at higher Cu2+/Al3+ mole ratio. The TEM analysis for particle size and size distribution revealed that the average particle size of Cu – Al bimetallic nanoparticles decreased with the increase of absorbed dose. It may be explained due to the competition between nucleation and aggregation processes in the formation of metallic nanoparticles under irradiation.

Journal of Radioanalytical and Nuclear Chemistry, 2012

Your article is protected by copyright and all rights are held exclusively by Akadémiai Kiadó, Bu... more Your article is protected by copyright and all rights are held exclusively by Akadémiai Kiadó, Budapest, Hungary. This e-offprint is for personal use only and shall not be selfarchived in electronic repositories. If you wish to self-archive your work, please use the accepted author's version for posting to your own website or your institution's repository. You may further deposit the accepted author's version on a funder's repository at a funder's request, provided it is not made publicly available until 12 months after publication.

In this letter, we investigate the fabrication of Double gate and Single gate Junctionless silico... more In this letter, we investigate the fabrication of Double gate and Single gate Junctionless silicon nanowire transistor using silicon nanowire patterned on lightly doped (10 5 cm-3) p-type Silicon on insulator wafer fabricated by Atomic force microscopy nanolithography technique. Local anodic oxidation followed by two wet etching steps, Potassium hydroxide etching for Silicon removal and Hydrofluoric acid etching for oxide removal, were implemented to reach the structures. Writing speed and applied tip voltage were held in 0.6 µm/s and 8 volt respectively for Cr/Pt tip. Scan speed was held in 1.0µm/s. The etching processes were elaborately performed and optimized by 30%wt. Potassium hydroxide + 10%vol. Isopropyl alcohol in appropriate time, temperature and humidity. The structure is a gated resistor turned off based on a pinch-off effect principle, when essential positive gate voltage is applied. Negative gate voltage is unable to make significant effect on drain current to drive the device into accumulation mode.

We present the fabrication, electrical characteristics, and effect of lateral gates in a junction... more We present the fabrication, electrical characteristics, and effect of lateral gates in a junctionless silicon nanowire transistor. The transistor uses silicon nanowire on silicon-on-insulator wafer fabricated with an atomic force microscope nanolithography technique. Using AFM nanolithography allows us to make a chemical contrast between locally oxidized part of the surface and unexposed surface. This chemical contrast affects as a mask and the active part of the device is finally obtained after two step etching. The structure is uniformly low-doped for source, drain, channel, and the lateral gates regions, and confirms the behavior of junctionless nanowire transistors. The output current is controlled by channel doping and mobility of carriers instead of gate capacitance and it basically uses bulk conduction instead of surface channel conduction. The fabricated device exhibits an on-off ratio of 2×10 6 and a subthreshold swing of 160 mV/decade.

Journal of Radioanalytical and Nuclear Chemistry, 2015

ABSTRACT Hollow Fe x Ni(1−x)OOH nanospheres with average diameter and shell thickness of about 15... more ABSTRACT Hollow Fe x Ni(1−x)OOH nanospheres with average diameter and shell thickness of about 15 and 5 nm were successfully synthesized for the first time through the radiation induced self-template method. The fast outward diffusion of Fe(III) ions due to Kirkendall effect between the core (FeOOH) and the shell (Fe x Ni(1−x)OOH) is the main reason for appearing the hollow nanoparticles. The results showed that a passive layer of Fe(III) species was formed at core and shell interface and Ni(II) ions play an important role in hollowing process of nanoparticles.

Beilstein journal of nanotechnology, 2012

A double-lateral-gate p-type junctionless transistor is fabricated on a low-doped (10(15)) silico... more A double-lateral-gate p-type junctionless transistor is fabricated on a low-doped (10(15)) silicon-on-insulator wafer by a lithography technique based on scanning probe microscopy and two steps of wet chemical etching. The experimental transfer characteristics are obtained and compared with the numerical characteristics of the device. The simulation results are used to investigate the pinch-off mechanism, from the flat band to the off state. The study is based on the variation of the carrier density and the electric-field components. The device is a pinch-off transistor, which is normally in the on state and is driven into the off state by the application of a positive gate voltage. We demonstrate that the depletion starts from the bottom corner of the channel facing the gates and expands toward the center and top of the channel. Redistribution of the carriers due to the electric field emanating from the gates creates an electric field perpendicular to the current, toward the bottom...

Journal of Materials Science

The structural changes of radiolytically prepared aluminium-copper (Al-Cu) bimetallic nanoparticl... more The structural changes of radiolytically prepared aluminium-copper (Al-Cu) bimetallic nanoparticles by adjusting the precursors' mole ratio and gamma radiation dose were investigated by transmission electron microscopy, field emission scanning electron microscopy/ energy dispersive spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy (FTIR), and X-band continuous wave electron paramagnetic resonance (EPR). The EPR spectrum was also analysed through the simulation of the powder-like EPR spectra. The results note that in prepared samples with higher Al contents, formation of coreshell structure is dominant, whereas in Cu-rich samples, the final structures are primarily in alloy and oxide forms. According to the analysis of data obtained from X-ray diffraction, FTIR, and EPR, we found that the unpaired electron of the Cu 2? ion in various phases play the main role in structural phase transformation of Al-Cu nanoparticles. Additionally, based on the information extracted from simulated EPR peaks of Cu-Cu, the diameter of the Cu core in core-shell structures was obtained. We showed that by increasing the gamma radiation dose from 80 to 120 kGy, the overall size of nanoparticles decreases from 9.47 to 3.75 nm, but the contribution of copper core increases from 11 to 22 % of overall particle size.