The properties of these polymers are very sensitive to fabrication conditions and to the type of preparation technique used. Therefore, the study of the properties of these conducting polymers with respect to different growing as well as ambient conditions is of high importance. These conjugating polymers thin films have been studied by many workers, because of their special electricalproperties, their considerable thermal stability and oxidation resistance, these properties are favorable in applications such as optoelectronic, biosensors, electrochromic displays and chemical sensors [8-12], electrode materials in electro-catalysis in solar energy conversion [13, 14]. These conducting polymers have excellent mechanical and electricalproperties and can be produced continuously as flexible film by electrochemical techniques. In Some applications of PANI has an electrical conductivity between 10 -10 ― 10 -2 (Ω cm) -1 and they are used as hole injection layers for flexible light emitting diodes [15, 16]. These polymers are useful in the design of new structures, which are stable, and soluble in some cases, they have a delocalized conjugated structure. Materials with conjugated structures have been extensively studied for their rapid photoinduced charge separation and a relatively slow charge recombination of hole-electron pairs . Liu and Coworkers  prepared PANI/Tio2 films and applied them to solar cells. Natural polyaniline has a forbidden band gap of 2.8 eV showing strong absorption for visible light; some researchers used it in photocatalysis [19, 20], doped polyaniline has an optical band gap 2.21 eV and room electrical conductivity (σ 25 = 3.12 x 10 -2 (Ω.cm) -1 ) . Films of PPY, PANI and PT are obtained directly through anodic polymerization of their monomers in aqueous or organic electrolytes. The preparation of PPY
Optical and ElectricalProperties of Vacuum Evaporated Sexithiophene Thin Films have been studied in the present work. The opticalproperties of Sexithiophene layers have been studied by absorption spectroscopy and fluorescence. From the optical studies, it has been observed that sexithiophene can be absorbed in the visible region and the electronic transitions have been occurred in the absorption spectra and fluorescence spectra. The weak fluorescence of 6T thin film would be an asset to the photovoltaic conversion of solar energy. The total conversion efficiency of the fabricated cells has been calculated as η = 0.7 10 -2 %. It is found that this very poor yield has been obtained mainly due to two factors. The first concerns the rate of photogeneration of free charges in the organic semiconductor since the excitons formed by light absorption of strong Frenkel excitons. The second is due to the small overlap of the absorption spectrum with the emission spectrum of the lamp. This manifest in the low lifetime of free carriers 4 3 µs from compared to the transit time 187 µ s which weakened due to the low carrier mobility.
Understanding the effect of electric current on ITO thin films is essential to increase the life-time of electronic devices. In this study, we analyzed the effect of electro-annealing in air and vac- uum on the structural, optical and electricalproperties of the crystalline ITO thin ﬁlms grown by large area DC magnetron sputtering at 250 C substrate temperature. Both for electro- annealing in air and vacuum, we observed improvement in the structural, optical and electricalproperties of the ITO thin ﬁlms due to the electro-annealing process. In comparison with electro- annealed ITO thin ﬁlms in vacuum, higher sheet resistances were
ENHANCEMENT OF OPTICAL AND ELECTRICALPROPERTIES OF ZNO THIN FILMS
Pristine and indium doped ZnO thin films were prepared on fused silica substrate using chemical spray pyrolysis technique. All films were vacuum annealed at 400 0 C for three hours at a vacuum of mbar. The XRD analysis revealed a shift of preferred orientation from (002) to (101) direction at higher indium doping concentration. A minimum sheet resistance of 1.986 X10 -2 Ωcm and a ium doped ZnO films. The band gap of ZnO films showed an increase with doping concentration, majorly due to Burstein Moss effect.
Al:ZnO films were deposited by spray pyrolysis. It was demonstrated that the choice of solvent has a profound effect on the structural properties of the films. Using methanol leads to oriented films, while using water leads to randomly oriented, rough, and hazy films. These results were confirmed by top view SEM, showing hexagonal columnar structures in the former and random faceting in the latter case. This also affects the morphology and thus the macroscopic opticalproperties of the films. Thin films grown by using water are much rougher than those grown using methanol, and thus the former have a higher haze value. Both solvents and salts have an effect on the electricalproperties of the films, with inorganic solvent and precursors leading to higher resistive samples in comparison to those grown by organic solvents and salts. Short post-annealing treatments lead to an improvement on the electricalproperties in both cases. An overall minimum resistivity of 7×10 -3 cm can be achieved reproducibly by employing spray pyrolysis using simple air blast nozzles. For smooth films grown in methanol Al-(ACAC) 3 was found to be the best
limitation can be ignored. The thickness, optical constants, and bandgap information of nanolaminates have been ex- tracted from SE analysis. With decreasing bilayer thickness, the absorption edge of extinction coefficient has a blue shift, and the optical band gap energies show a growing trend, because the BM effect, the quantum confinement ef- fect, and the characteristic evolution of nanolaminates have significant influence on them. This blue shift also occurs in the transmission and absorbance spectra with high trans- mittance beyond 90% in the visible and near-infrared re- gion. Moreover, by varying the bilayer thickness, the electricalproperties also show two kinds of characteristics, and the modulation of characteristics is realized. The nano- laminates 2 (25/25 nm), 5 (10/10 nm), and 10 (5/5 nm) show high carrier concentration above 10 19 cm −3 , which can be applied as transparent conductive material. And also, the nanolaminates 25 (2/2 nm) and 50 (1/1 nm) pos- sessing high resistivity can be used as high-resistivity layer in semiconductor manufacturing process.
Size-dependent photoluminescence characteristics from Ge nanocrystals embedded in different oxide matrices have been studied to demonstrate the light emission in the visible wavelength from quantum-confined charge carriers. On the other hand, the energy transfer mechanism between Er ions and Ge nanocrystals has been exploited to exhibit the emission in the optical fiber communication wavelength range. A broad visible electroluminescence, attributed to electron hole recombination of injected carriers in Ge nanocrystals, has been achieved. Nonvolatile flash-memory devices using Ge nanocrystal floating gates with different tunneling oxides including SiO 2 , Al 2 O 3 , HfO 2 , and variable oxide thickness [VARIOT] tunnel barrier have been fabricated. An improved charge storage characteristic with enhanced retention time has been achieved for the devices using VARIOT oxide floating gate.
The calculation results show that optical band gap of Al x Ga 1−x N crystal is widened that the E g of Al x Ga 1−x N can be ad- justed by the x, and the absorption spectrum shifts to high-energy direction with the increase of the x, and then the Fermi energy moves to the top of valence band slightly which leads to that conductivity weakened after mixed with the Al. At the same time, the variation trends of complex dielectric function, absorption spectrum and transitivity have been made clear, and the results show that Al x Ga 1−x N compounds can achieve the theoretical design of photoelectric per- formance. In a word, Al x Ga 1−x N crystals are potential semiconductors with very remarkable photoelectric properties, which can be applied in the development of the diversified GaN devices.
sulphate , bisglycine manganese chloridedihydrate , triglycine selenate  and glycine silver nitrate , are known to have ferroelectric properties. The ferroelectric materials have a variety of functional device capabilities such as piezoelectric, actuator, nonlinear optical devices and high permittivity materials. Recently it was also reported that some of the glycine compounds like trisglycine zinc chloride also exhibit properties like SRS, SHG and THG in addition to ferroelectric properties . Glycine in the zwitter ionic form also forms one dimensional chain structures and two dimensional layered structures in metal amino carboxylate coordination polymers . The present investigation deal with the growth of bis-glycine cadmium chloride single crystal was grown by slow evaporation technique. The grown crystals were characterized by single crystal X-ray diffraction analysis, UV analysis, dielectric, SHG and photoconductivity measurements. The results of these studies have been discussed in this paper in detail. The optical investigations and electrical conductivity studies are carried out for grown crystal to find the suitability of the materials for device fabrications. Photoconductivity studies have also been analysed to confirm the dielectric behavior which is responsible for the induced polarization in the medium.
Subsequently this was heated for 30 min at 250 o C in an Ar atmosphere at a pressure of 1 mbar. The excess of sulphur is designed to ensure full conversion of the precursor layer during the heating process. Hot probe measurements were made immediately after fabrication of the film, demonstrating p-type conductivity. The surface morphology of the fabricated films was analysed using scanning electron microscopy (SEM) with wavelength-dispersive X-ray (WDX) microanalysis providing details of the elemental composition and homogeneity. X-ray diffraction (XRD) and Raman spectroscopy were used to investigate the structural properties of the films and the presence of secondary phases. The photoresponse was measured by immersing the films in a glass cell with 0.2 M aqueous solution of Eu(NO 3 ) 3 , as an electron scavenging redox electrolyte, and illuminating with 75 Hz chopped monochromated light from a tungsten halogen lamp. A three electrode configuration was used with an Ag/AgCl reference electrode, a counter platinum electrode in addition to the molybdenum back contact.
Generally speaking, the light-sensitive devices convert a photon flux (light) into a flux of free charge carriers. And with respect to application, those devices can be divided into two major types. One type is energy-harvesting devices such as the solar cell which delivers electrical power to a load. Another type of device is the photo-detector or image sensor which delivers a photo-current signal. Both of these areas gain considerable popularity among researchers. The solution process-ability of organic photovoltaic devices reduce cost, energy consumption and environmental impact during manufacturing, which makes the OPVs a promising alternative candidate for renewable energy. Moreover, its flexible feature and potential for cost-effective large-area fabrication makes imaging systems another interesting field of applications.
However, for the use in devices, it is necessary to optimize the conditions for the preparation of film with uniform thickness, good optical transparency and significant mechanical stability.
The present work describes the preparation of high-quality PVA films from PVA powder with medium molecular mass (M w was within 75,000-80,000 g/mol) and hydrolysis > 98 mol%. This PVA powder is easily available commercially and widely used; thus, it would be interesting and useful to optimize the conditions for the preparation of films with it.
integrity of the films particularly for high annealing temperature T > 623 K.
The as-deposited CdS film shows a mixture of 50% hexagonal and 50% cubic phases where the hexagonal phase becomes dominant upon annealing. This goes along with increasing crystallite size and a reduction of the dislocation and strain of the films. Structural phase transformation from the metastable cubic phase to the stable hexagonal phase is observed at 823 K. The changes are likely of an entirely structural nature, and not of a chemical nature. There is a red shift effect of the transmission spectrum after annealing, which means that there is some decrease of the band gap energy after annealing (from 2.42 eV to 2.28 eV). In addition to that, the Urbach tail of the absorption edge decreases with increasing annealing temperature, and increases again at T > 623 K. The absorption and the extinction coefficient calculated at l = 550 nm show strongly temperature dependent behavior. The film annealed at 423 K shows the highest conductivity having crystallite size around 88 nm. The temperature dependence of electrical con- ductivity of the film increases nonlinearly with increas- ing temperature. The nonlinearity of the evolution of the Urbach energy versus annealing temperature, that is, the fact that there is a minimum in the intermediate temper- ature range at around 623 K, will require further study to determine its microscopic origin.
All the above methods need catalysts such as Ni, Fe …etc. In our research, we use plasma scattering of car- bon rod to prepare Si-C junction, which was studied earlier thoroughly in our published paper .
In this paper, we want to find the effect of changing the sputtering current and the thickness effect on the structural and electricalproperties of the CNT layer in the Si-C junction.
The optical transmission spectra of Sb:F:SnO 2 films using solution amount of 20 cc, 25 cc and 30 cc were recorded in the wavelength of 300 to 800 nm using Shimadzu UV-1800 spectrophotometer. The transmission spectra of SnO 2 :F:Sb layers were shown in Figure 4-a. The transmittance value of 40% to 70% was found in the visible region of 400-700 nm.
Single crystal of L-Prolinium Tartrate (LPT) was grown from aqueous solution by slow evaporation technique. The crystalline nature of the material has been confirmed by single crystal X-ray diffraction. The optical transmission study reveals the transparency of the crystal in the entire visible region and the cut off wavelength has been found to be 220 nm. The optical band gap is found to be 3.60 eV. The transmittance of LPT crystal has been used to calculate the refractive index n, the extinction coefficient K and both the real ε r and imaginary ε i components of the dielectric constant as functions of wavelength. The AC and DC conductivity studies of the crystals were carried out to determine the activation energy for conduction process. The photoconductivity studies reveal that the crystal exhibits negative photoconductivity.
Keywords: CdSe: Nd nanocrystalline thin film, Photoluminescence, Electricalproperties, Solar Cell
II-VI Semiconductor are used in many applications such as solar cell, LED, . Semiconductor thin films give better results over microcrystalline thin film. Development of nanocrystalline thin film reduces the size of the electronics devices and enhances the efficiency. Uniform thin film produced by thermal evaporation , successive ionic layer adsorption and reaction (SILAR) , Physical vapour deposition , Electrochemical , Photochemical , Metal oxide chemical vapour deposition (MOCVD) , Photo electrochemical , Electron beam evaporation  are very costly. High manufacturing cost increases the prices of the devices. To reduce the cost of the devices it is essential to adopt a very cheap manufacturing method of thin film preparation.
3-2 The Optical Part:
The opticalproperties of Se films for 500 nm thickness at different annealing temperatures have been study by UV-Visible transmittance spectrum.
The transmission spectra of annealed and as-deposited films have been illustrated in Fig 2. From these plots shows that the increasing of annealing temperature caused to shifts the peak of transmittance spectrum toward the shorter wavelengths (higher energies compared with the as-deposited film, which means the decrease in disorder and defect density in the structure gives rise to increase in the optical band gap. In addition, the saturation of dangling bonds in the amorphous structure results in increase in band gap.
Rare earth compounds are interesting from both a theoretical point of view and for their applications. That is the reason why determining their optical and electricalproperties deserves special attention. In this article, we present the conditions we obtained homogenous CeNi 5 thin films of nanometer thicknesses. To achieve this goal, our method of choice was laser-induced vaporization, using short and modulated impulses, with electro-optical tuning for the quality factor. The layers that were deposited at a single laser burst had thicknesses between 1.5 and 2.5 nm, depending on the geometry of the experimental setup.