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04- International Journal of Thin Films Science and Technology



Cross sectional TEM characterization of epitaxial silicon film grown using hot wire chemical vapor deposition

Abul Hossion,
Abstract :
We have investigated epitaxial growth of poly crystalline intrinsic silicon film grown on glass and Si/SiO2 substrate using hot wire chemical vapour deposition technique. We have grown 20 nm nucleation layer at 400C followed by an epitaxial growth of 200 nm thick at 600C. Further 800 nm thick layer grown on top using high hydrogen silane ratio of 15:5. Hydrogen soaking was performed for well passivated film. Evaluation of different layers was performed by cross sectional transmission electron microscopy. Poly crystalline as well as epitaxial and columnar growth regions were well observed.


Enhanced activity of chemically Synthesized nanorod Mn3O4 thin films for high performance Supercapacitors

Immanuel P, G.Senguttuvan, K. Mohanraj,
Abstract :
Herein we describe a cost effective method for fabricating high performance and flexible supercapacitor based on the transition metel oxides of Mn3O4 thin films. The Mn3O4 prepared by SILAR method at different cycles such as 25, 50, 75 and 100 cycles. The prepared Mn3O4 thin films were characterized by means of structural, morphological and electrochemical studies. The structural studies of X-ray diffraction (XRD) revels that 75 cycles have a good crystalline nature with tetrahedral structure. Fourier transform infrared spectroscopy (FTIR) indicates the functional group of Mn-O. Raman spectra revels that formation of Mn3O4 thin films. SEM analysis depicted the structure of the Mn3O4 thin films have a rod-like structure, TEM images shown the SAED pattern and lattice fringes of Mn3O4. The electrochemical measurements of CV, GCD and impedance measurements are investigated using the 1M Na2SO4 electrolyte. In the electrochemical measurement Mn3O4 thin films exhibits the maximum specific capacitance value of 295 Fg-1 at the scan rate of 2 mVs-1.


Investigation of crystal growth techniques and advantages

Maryam Kiani,
Abstract :
An ideal crystal is built with regular and unlimited recurring of crystal unit in the space. Crystal growth is defined as the phase shift control. Regarding the diversity crystals and the need to produce crystals of high optical quality, nowadays many methods have been proposed for crystal growth. Crystal growth of any specific matter requires careful and proper selection of growth method. Based on material properties, the considered quality of the crystal, and crystal size, crystal growth methods can be classified as the following: solid phase crystal growth process, and liquid phase crystal growth process which is divided into two major sub-groups of growth from the melt and growth from solution, vapor phase crystal growth process. Methods of growth from solution are generally very important. So, most materials can growth by these methods. Methods of crystal growth from the melt are Czochralski method (tensile), the Kyropoulos, Bridgman-Stockbarger, and zone melting method. In growth of oxide crystals with good laser quality, Czochralski method is still predominant, and it has wide commercial uses in production of most solid-phase laser materials


Analytical Modeling and Simulation of Highly Sensitive n-RADFET Dosimeter

Shweta Tripathi, Srijan Pathak, Spriha Singh, Spriha Singh, Tanya Sharma, Ankush Agarwal,
Abstract :
In the present paper, we have developed a model of a n-RADFET dosimeter device and studied the effects of ionizing radiation on the surface potential and threshold voltage characteristics of the device. Also, a detailed simulation analysis of the device has been done to obtain some further results. Interestingly, it has been observed in the present study that a high sensitivity can be obtained for RADFET by using n-MOSFET device. The results of this study are expected to be useful in establishing the effectiveness of n-RADFET device as a dosimeter.


On variation of rate of growth of epitaxial layers by variation of substrate heating

Abstract :
In this paper, we estimate the rate of growth of epitaxial layers from the gas phase. We study dependence of the rate on the value of the heating of the substrate. By using the previously introduced approach of mass and heat transfer analysis, analytical de-pendencies of the considered rate on the parameters were obtained. In this paper based on recently introduced approach we analyzed mass and heat transport during growth of epitaxial layers in reactors for epitaxy from gas phase with sloping keeper with account native convection. Based on recently introduced approach we estimate rate of growth of films and analyzed dependences of the rate on physical and technological parameters.


Effect of dyes Nano-material electrodes for exploration of dye sensitized solar cells

Abstract :
The demand for suitable thin films and photoelectric electrodes for renewable and sustainable energy continues to grow. In the exploration of dye-sensitized solar cells (DSSC) recent and increased involvement in the application of nanomaterial-based electrodes and the effects of their unique electronic properties has drawn a lot of attention and investigation. This was an attempt to contribute to the investigation by using different dyes on TiO nanoparticles.


Nano Structural Properties of Lead Doped Cadmium Sulfide (Cd1-xPbxS) Thin Films Deposited by Spray Pyrolysis Technique

Abstract :
Lead doped cadmium sulfide thin films Cd1-xPbxS (0 ≤ x ≥ 0.20) were deposited onto a glass substrate at a temperature of 523K at a low cost spray pyrolysis technique. The films were characterized by their structural and optical properties, by energy dispersive x-ray analysis, scanning electron microscopy, x-ray diffraction respectively. X-ray diffraction patterns of the films are identified as (100), (002), (101), (102), (110), (103) and (201) planes which are hexagonal crystal structure. There is no extra peak developing with the increasing Pd concentration. The direct band gap energy of the film is strongly dependent on the concentration, x. and this value is varied from 2.52 eV to 2.17 eV which is required for solar cell and opto-electronic device applications.


Effect of TM (TM= Sn, Mn, Al) doping on the physical properties of ZnO thin films grown by spray pyrolysis technique: A comparative study

Amroun Mohamed Nadhir,
Abstract :
ZnO:TM (TM=Sn, Mn, Al) thin films were successfully deposited on glass substrates by spray pyrolysis technique. X-ray analysis shows that ZnO:TM thin films crystallize in hexagonal structure with a preferred orientation of the crystallites along (002) direction and the crystallite size had increased with TM doping. The effect of TM type on the structural parameters was studied. These films were found to have direct band gap energy lying in the range of 3 2.25 eV and the average transmittance varies from 75 to 85 % with TM doping. The lowest figure of merit observed in the present study is 4.1310-5 (Ω-1) for AZO thin films. All the optical expected absorption capacity and photocurrent (jph) depend on the TM type. The optical constants such as the urbach energy, effective mass of the carriers (m*), refractive index (n) and extinction coefficient (k) were also evaluated. The AZO thin films exhibited the lowest resistivity (1.79 10-1 Ω cm).



Gopalakrishnan P,
Abstract :
Tin disulphide (SnS2) thin film has been prepared on glass substrate by chemical spray pyrolysis technique using the precursor solutions of tin (IV) chloride and thiourea, which were atomized with compressed air as carrier gas. Thin layer of SnS2 film has been grown at lower thermal energy of 473 K. The Structural properties have been analyzed by X-ray diffraction (XRD) and surface morphology by SEM micrograph. The optical properties of the thin film deposited was obtained using experimentally recorded transmission spectral data as functions of the wavelength, in the range of 400 800 nm. An analysis of the spectral absorption of the deposited film revealed optical direct forbidden and indirect band gap energy of 2.2 eV and 2.35 eV respectively for SnS2 layer. The DC room temperature electrical resistivity of this film is determined using four probe technique as 4.2 x 104 Ω cm in dark and 1.65 x 103 Ω cm in light respectively. Activation energy of this thin film was determined by Arrhenius plot.


Enhanced Light Trapping On Thin-Film Solar Cells from Scattering Nano Particle Arrays

Sukanya.R, T.Sivakumar,
Abstract :
Thin-film solar cells focus on lowering the amount of material used as well as increasing the energy production. Inexpensive fabrication methods and effective light trapping are requisite for Thin Film solar cells to attain cost-competitiveness. The very optimistic reason is that the efficiency of a solar cell depends on both the quality of its semiconductor active layer, as well as on the presence of other dielectric and metallic structural components which improve light trapping and exploit plasmonic enhancement. Thin-film polycrystalline silicon is an attractive material for use in solar cells due to ideal band gap and its relative abundance. This paper keep in focus two main objectives, a highly scalable and inexpensive HWCVD deposition method that produces high quality material at minimal cost and the Evaluation of light trapping mechanisms employing FDTD simulations to determine the optimal expected optical characteristics of a thin-film device structure and to examine the potential of surface structures that will increase photon absorption in Thin-films surface, or inside the solar cells are crucial in order to make thin film solar cells viable. Surface structures were examined by modeling SOI structures with 220nm thick silicon device layers and decorating the surface with nanoparticle arrays of both metal and dielectric material. This is to gain insight into the potential for scattering structures on to the surface of a thin-film solar cell to increase the fraction of light incident and redirected laterally into the film, thus increasing the path length and absorption. The careful examination of scattering cross section, Bloch modes, Thin-film wave guiding modes and Plasmonic near-field enhancement resulting from these surface arrays ,these observations finds significant enhancement in light capturing with these structures.


Fabrication, characterization and performance analysis of dye-sensitized solar cell using natural dye

M. F. Hossain, M. A. Emran,
Abstract :
The nanocrystalline TiO2 film deposited on SnO2:F (FTO) coated glass substrate was firstly sensitized with Amaranthus gangeticus leaves extract dye (A) in three different seasons: winter, summer, and autumn. Maximum efficiency of 0.413% was measured in autumn season using A dye. Then another two films were sensitized with B and M dyes in autumn where B was extracted from Basella alba and M was the mixture of A and dye extracted form Syzygium cumini (previous work), and they show the efficiency of 0.115% and 0.084% respectively. Finally, the autumn and A were determined as favorable season and dye respectively.


Chemical deposition of polycrystalline ZnSe thin films from Malonic acid solution: Nucleation and growth mechanism, structural, optical and electrical studies

Abstract :
Zinc selenide (ZnSe) polycrystalline semiconductor thin films have been synthesized by dip method in malonic acid solution. The formation of nucleus and growth process of this technique has been studied. The XRD pattern shows a characteristic cubic structure with a (111) crystallographic preferred orientation. SEM studies reveal that grains are uniformly dispersed on the surface of the substrates. The optical energy gap was found to be 2.80 eV. The activation energies are 0.053 and 0.317 eV for low and high temperature region, respectively obtained from electrical measurement.

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