1,721,068 research outputs found
Investigation of optical and structural properties of sonochemically prepared 3-mercaptopropionic acid capped bismuth sulfide nanostructures
No full text© 2016, National Institute of Optoelectronics. All rights reserved.3-mercaptopropionic acid(3-MPA) capped bismuth sulfide nanostructures have been synthesized using an ultrasound-assisted method in an aqueous medium and some of their optical and structural properties have been characterized by X-ray diffraction (XRD), Scanning electron microscope (SEM) and UV-Visible spectroscopy. Reference experiments have also been performed in the absence of capping agent to clearly illustrate the effect of capping mechanism. XRD results show broadening of peaks, suggesting formation of the nanometer sized materials and more smaller sizes in the presence of 3-MPA. UV-Vis absorption spectroscopy results show shifting toward lower wavelength, also confirming the formation of nanostructures with smaller dimension. Surface morphology of the prepared material shows the formation of nearly spherical aggregates of nanoclusters
Preparation of Cadmium Sulfide Nanostructures in Presence of Polyvinyl Alcohol and Polyvinylpyrrolidone as a Capping Agent and Investigation of Their Structural and Optical Properties
No full textIn this research, cadmium sulfide nanostructures have been prepared by an ultrasound-assisted method in presence of polyvinyl alcohol (PVA) and polyvinylpyrrolidone (PVP) as capping agents. The effects of two different capping agents on the structural and optical properties of cadmium sulfide nanostructures have been investigated by X-ray diffraction (XRD), UV-Vis spectroscopy, scanning electron microscopy (SEM) and Fourier transform Infrared (FT-IR) spectroscopy. The XRD patterns show the high purity of samples. The mean crystal's sizes have been estimated by Debye-Sherrer equation and results show the mean crystallite size is decreasing with increase capping agent concentrations. UV-Vis spectroscopy results show a shift in the peaks and broadening with the PVA and PVP increasing. The broadening of the absorbance spectrum with increasing in capping agent concentrations is due to the quantum confinement of nanostructures. The band gap of prepared samples has been estimated by Tauc equation and graph and results show that the band gaps of samples are increasing with increase in the capping agent's concentration. The SEM images show the distribution of the uncapped sample is different from capped samples. FT-IR spectroscopy results show by increasing of capping agent concentration the energy between the functional group is changed and some peaks show a slight shift
Dielectric properties of CdS-PVA nanocomposites prepared by ultrasound-assisted method
No full textThe electric and dielectric properties of ultrasound-assisted synthesized CdS nanocrystals-PVA mixture were studied in temperature range of 298 K to 498 K and frequency range from 200 Hz to 1 MHz. Scanning Electron Microscopy (SEM) shows that the morphology of CdS nanoclusters are formed in the form of mostly spherical nanoparicles with average size 10 nm. It was found that the nature of polarization processes in pure PVA and CdS-PVA nanocomposites are different. This is due to interfacial polarization in nanocompisites
Optical characterization of semiconductor CdS nanoparticles formed in polymer matrix
No full text© 2016, National Institute of Optoelectronics. All rights reserved.The optical properties of CdS nanoparticles (NPs) are explored as a function of nanoparticle size and concentration. Nanocomposite (NC) thin films with semiconductor CdS nanoparticles formed in a polymer matrix using successive ionic layer adsorption and reaction (SILAR) technique showed very attractive optical properties due to quantum confinement effects. For bulk CdS materials, the absorption peaks can only be tuned in a narrow range. The nanostructure size and shape were characterized by scanning electron microscope (SEM), the optical properties were studied by UV-Vis spectroscopy, FT-IR and photoluminescence spectroscopy (PL)
The influence of the physicochemical processes on the electrical response of Al/p-Si structure with etched surface
No full textIn this paper, the electrochemical etching process is used for surface modifcation of the p-Si wafer, named as porous silicon (PS), in the metal–semiconductor (MS) type Schottky diode (SD) with a structure of Al/p-Si. Five regions of PS wafer with diferent etching rates are selected for comparison of them which are called P2, P3, P4, and P5 (P1 is the reference area without porosity). The morphological, structural, and electrical properties of the PS used in the MS-type SD are investigated using feld-emission scanning electron microscope (FE-SEM) images, energy dispersive X-ray (EDX) analysis, and current–voltage (I–V) characteristics, respectively. The FE-SEM images show a meaningful efect on the porosity. The EDX spectrum demonstrates the importance of the chemical efects in addition to the physical changes in the porosity process of the p-Si wafer. The reverse-saturation current (I0), ideality factor (n), barrier height at zero-bias (?B0), and series/shunt electrical resistances are also computed and compared. Some of these parameters (n, Rs, BH) are determined using diferent methods, namely Thermionic emission (TE), Cheung functions, and modifed Norde, and they exhibit strong agreement with each other. The energy-dependent profles of surface states (Nss) are estimated from the I–V data by considering the voltage dependence of ?B (V) and n(V). All the experimental fndings indicate that the etching process of the p-Si wafer signifcantly infuences the electrical performance of the Al/p-Si Schottky diode by increasing the extent of etching
Comparison of quantum confinement effect on the reduced effective mass of CdSe nanocrystals prepared by different methods
No full textBased on Effective Mass Approximation (EMA) and Hyperbolic Band Model (HBM), the effect of quantum confinement upon the energy band gap and reduced effective masses of CdSe nanoparticles has been examined. The size of nanoparticles were used from experimental data, such as X-ray diffraction (XRD), Scanning and transmission electron microscopy and the band gap also derived from optical spectroscopy. Also preparation of CdSe nanocrystals was achieved via ultrasound- assisted method. X-ray diffraction (XRD), Scanning electron microscopy (SEM) and Uv-visible spectroscopy were used to characterize the structural and optical properties of as-prepared nanostructures. The experimental results showed that the as-prepared CdSe nanostructures are formed with very small nanometer size, which showed a blue shift of about 0.4eV in energy gap. Theoretical study showed that the value of the reduced effective mass of charge carriers in quantum sized CdSe materials differs from its bulk crystal. The comparative analyses and the main reasons of the changes in reduced effective mass value in the case of CdSe nanoparticles are briefly discussed
The Structural and Electrical Properties of the Au/n-Si (MS) Diodes with Nanocomposites Interlayer (Ag-Doped ZnO/PVP) by Using the Simple Ultrasound-Assisted Method
No full text© 1963-2012 IEEE.In this paper, Au/Ag-doped ZnO/polyvinyl pyrrolidone (PVP)/n-Si [metal-polymer-semiconductor (MPS)] Schottky Barrier Diodes (SBDs) were fabricated. The structural properties of the Ag-doped ZnO/PVP nanocomposites have been investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive X-ray (EDX) analyses. The XRD pattern indicated that the samples have high purity ZnO and Ag materials and have not observed other peaks. The mean crystallite size of nanoparticles was calculated using Debye-Scherer's equation and the measured sizes reveal clearly the formation of small nanocrystals. The SEM and EDX results show the sheetlike ZnO nanostructures and also confirm the presence of Zn, O, and Ag materials with the nonstoichiometric ratio. The values of ideality factor (n), zero-bias barrier height (ΦB0), and series resistance (RS) of the MPS-type SBD were obtained from both the thermionic emission (TE) and Cheung function and the observed some discrepancy between them was due to the voltage-dependent of these parameters and the nature of the calculation method. The value of surface states (Nss) was changed from 2.2 × 1013 eV-1 cm-2 at (Ec ? 0.44) eV to 8.19 × 1012 eV-1 cm-2 at (Ec ? 0.69) eV and these values are more suitable for the MPS-type SBD. The values of doping-donor atoms (ND), depletion layer width (WD), and φB [capacitancevoltage (C?V )] were obtained from the reverse bias C-2?V plot as a function of frequency. While the value of ND decreases with increasing frequency,WD increases almost as exponentially. However, there is a good relationship between φB (C?V ) and ln(f )
Modified co-precipitation process effects on the structural and magnetic properties of Mn- doped nickel ferrite nanoparticles
No full textManganese doped Nickel ferrites nanoparticles (NPs) have been synthesized by modified co-precipitation method for investigating the effects of adding dopant ions after formation of nucleation centers in the reaction medium. The structure and magnetic properties of the as-synthesized samples have been studied by X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FT-IR) and Vibrating sample magnetometer (VSM). The structural results showed that all the samples have cubic spinel phase with the average 21 nm crystallite size. In addition, variation of the preferred XRD peak from (311) orientation to (440) occurred because of the compressive strain in the structure which was calculated by means of Williamson-Hall method (W-H). Adding dopant ions, after nucleation, caused strain, spin canting and reduction of saturation magnetization
The influence of post-annealing treatment on the wettability of Ag+/Na+ ion-exchanged soda-lime glasses
No full textIn this paper, the effect of thermal annealing and the duration of ion-exchange on the wetting parameters of the Ag+/Na+ ion-exchanged glasses have been reported. The analysis of wetting angle in different post-annealing temperatures shows that the wetting angle is increased by increasing the annealing temperature. The wetting parameters of Ag+/Na+ ion-exchanged glasses at different ion-exchanged periods of time have been also investigated. Scanning electron microscopy (SEM), UV-Visible spectroscopy and Fourier transform infrared (FTIR) spectroscopy have been used for determination of surface morphology and composition analysis of the prepared samples. The results of SEM show changes in the surface of the samples for different post-annealing temperatures. The optical characterization using UV-Vis spectroscopy shows an increase in the intensity of the absorption peak with increasing the ion-exchange duration. The FTIR spectroscopy confirms the formation of silver oxide material on the surface of Ag+/Na+ ion-exchanged glasses. (c) 2013 Elsevier B.V. All rights reserved
Comparison of electrical properties of MS and MPS type diode in respect of (In2O3-PVP) interlayer
No full text© 2019 Elsevier B.V.In this study, the electronic properties of Au/n-Si (MS) and Au/(In2O3-PVP)/n-Si (MPS) diode have been investigated to see the effects of an organic (In2O3-PVP) interlayer by utilizing voltage-dependent current (I) and capacitance (C) measurements. The organic indium oxide (In2O3) nanostructures were characterized by XRD, SEM and UV–Vis spectrophotometer techniques. The rectifying ratio (RR) of the fabricated MS and MPS diode at ± 3 V was found as 1.89 × 103 and 6.18 × 103, respectively. The electronic parameters for instance the ideality factor (n) and barrier height (ΦBo) of MS and MPS diode were found as 1.94 and 2.20, and 0.73 eV and 0.76 eV, respectively. Additionally, series resistance (Rs), n, and ΦBo values were calculated by using Cheung's functions as second way to see the used calculation method and voltage effects on them. Therefore, the Rs and ΦBo values were determined from both the Norde method and C–V characteristics
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