Structural Properties of Magnesium Oxide Thin Films Deposited by Spray Pyrolysis Technique

In this work, structural properties of magnesium oxide films have studied by X-ray diffraction methods. MgO obtained by spray pyrolysis technique at the different substrate temperatures on the glass substrates. The 0.2 M magnesium chloride hexahydrate aqueous solution was selected as a precursor in the solution. The influence of substrate temperature on the phase composition, texture quality, coherent scattering domain size and lattice constant of the material was investigated. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3710

Porous silicon & titanium dioxide coatings prepared by atmospheric pressure plasma jet chemical vapour deposition technique-a novel coating technology for photovoltaic modules

Atmospheric Pressure Plasma Jet (APPJ) is an alternative for wet processes used to make anti reflection coatings and smooth substrate surface for the PV module. It is also an attractive technique because of it’s high growth rate, low power consumption, lower cost and absence of high cost vacuum systems. This work deals with the deposition of silicon oxide from hexamethyldisiloxane (HMDSO) thin films and titanium dioxide from tetraisopropyl ortho titanate using an atmospheric pressure plasma jet (APPJ) system in open air conditions. A sinusoidal high voltage with a frequency between 19-23 kHz at power up to 1000 W was applied between two tubular electrodes separated by a dielectric material. The jet, characterized by Tg ~ 600-800 K, was mostly laminar (Re ~ 1200) at the nozzle exit and became partially turbulent along the jet axis (Re ~ 3300). The spatially resolved emission spectra showed OH, N2, N2+ and CN molecular bands and O, H, N, Cu and Cr lines as well as the NO2 chemiluminescence continuum (450-800 nm). Thin films with good uniformity on the substrate were obtained at high deposition rate, between 800 -1000 nm.s-1, and AFM results revealed that coatings are relatively smooth (Ra ~ 2 nm). The FTIR and SEM analyses were better used to monitor the chemical composition and the morphology of the films in function of the different experimental conditions. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/2790

Effect of Substrate Temperature on the Electrochromic Properties of Nickel Oxide Thin Films by e-Beam Evaporation Method

Nickel Oxide (NiO), an anodic coloring material, is used as a counter electrode layer in Electrochromic (EC) devices in combination with Tungsten Oxide (WO3) as an EC layer. The NiO thin films were prepared on glass and indium tin oxide coated glass substrates by e-beam evaporation technique at different substrate temperatures ranging from room temperature (27 C) to 400 C. The crystallization of the film improves with increase in substrate temperature as inferred from the glancing incident X-ray diffraction measurement. The increase in substrate temperature of the films causes an increase in the transmittance. The electrochromic properties of NiO thin films were investigated in an aqueous alkaline electrolyte (1M KOH) by means of transmittance, cyclic voltammetry (CV), and chronoamperometry (CA) measurements. It is found that films prepared at lower substrate temperature, up to 100 C, have better EC properties. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3532

Influence of the Substrates Nature on Optical and Structural Characteristics of SnO2 Thin Film Prepared by Sol-Gel Technique

In this presentation we synthesized SnO2 thin film by sol-gel process. Starting from Tin(II) chloride as precursor and methanol as solvent the film was deposited on glass and quartz substrate by novel dip coating method. Structural and morphological analysis was carried out by X- Ray diffraction (XRD) mea-surement and Scanning electron microscopy (SEM). Optical characteristics were analyzed from the study of transmission spectrum data obtained by UV / VIS Spectrophotometer. It is observed that the transmission and grain size were more in case of quartz than glass substrate whereas the band gap was more in glass than quartz substrate. From XRD measurement it was confirmed the tetragonal structure of SnO2. EDS analysis depicts the weight percentage of Sn and O as 78.71 % and 21.29 % respectively and also confirms the purity of the film. From the study we concluded that the structural configuration changed a little with change in substrates at same conditions and quartz is the preferable substrate than glass. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3194

A Strategic Review Of Reduction Of Dislocation Density At The Heterogenious Junction Of Gan Epilayer On Foreign Substrate

Now-a-days for long range microwave communication, especially for space applications, devices capable to operate at a high power and high frequency are desired. Compound Semiconductor (CS), mainly Gallium Nitride (GaN) based heterostructure electronic devices are the only available solutions till now to fulfil these criteria. However, looking from a cost and manufacturing perspective, GaN substrate has considerable drawbacks like non-availability, expense as well as compulsion to use older technologies for device designing as the wafer diameter is small. A potential solution for performance/cost dilemma is to grow high quality GaN as active layer on a well matured substrate by metamorphic technique. Metamorphic buffer technology allows the device designer an additional degree of freedom to optimize the transistor at high frequency for high gain and power applications. But this metamorphic buffer technology has some drawbacks, too. The main limiting factor for this technology is the propensity to develop dislocation at the heterojunction due to lattice mismatch between the grown layer and the substrate. A good quality metamorphic buffer can only be achieved by reduction of dislocation density at the heterojunction. This paper reviews the progress being made towards reduction of dislocation density of GaN based devices grown on Silicon Carbide (SiC), Sapphire (Al2O3) and Si substrate, respectively, in terms of material parameters and growth issues. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/934

Photoluminescence of high optical quality CdSe thin films deposited by close-spaced vacuum sublimation

Polycrystalline CdSe thin films (d¼0.1–3.0 μm) have been deposited on a glass substrate by means of the close-spaced vacuum sublimation technique. X-ray diffraction measurements have shown that the films obtained at Тs>473K have only wurtzite phase. The influence of deposition conditions, inparticular,the substrate temperature on the photoluminescence(PL) of CdSe films spectra was investigated. This let us study the effect of glass substrate on their optical quality as well as determine the nature and energy structure of the intrinsic defects and residual impurities in the films. The presence in PL spectrum of the most intense sharp donor boundex citon D0X-line for CdSe films obtained at Ts=873K indicates the n-type conductivity and their high optical quality. Intensive PL bands in the spectral range 1.65–1.74 eV were also observed, which are associated with the recombination of donor–acceptor pair swith the participation of the shallow donor and acceptor centers caused by Na(Li) residual impurities. As a result of the study of the PL spectra of CdSe films the optimal temperature conditions of their growth were determined, namely, the substrate temperature Ts=873K and the evaporator temperature Te=973 K. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/37060This research has been supported by the Ministry of Education and Science of Ukraine (Grant No.0110U001151) by the National Academy of Sciences of Ukraine (Grants Nos.BС-157-15andB-146-15)

Structural Properties of ZnO Thin Films Obtained by Chemical Bath Deposition Technique

Zinc oxide thin films have been deposited onto glass substrate from zinc sulfate, ammonia and thiourea aqueous solution by chemical bath deposition. In the work this were specified solution preparation procedure and optimized the composition of the solution and content of component in it. X-ray difraction and high-resolution scanning electron microscopy were used to characterize structure formation of obtaining ZnO films. As a result of investigation was determined the effect of time deposition on the structural and substructural properties such as lattice parameters, texture quality, coherent scattering domain size. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3507