Papers by Keyword: Thin Film

Abstract: Gallium or sulphur additions in CuInSe₂ were prepared using RF magnetron sputtering and pulsed laser deposition respectively. All of the observed thin films show a chalcopyrite structure with the S addition increases the favourable (112) peak. The optical absorption coefficients were slightly decreased. The films energy band gap could be shifted from 1.04 to 1.68eV by adjusting the mole ratio of S/(S+Se) and In/(In+Ga). It is possible to obtain the optimum energy band gap by adding S solute or Ga at a certain ratio in favour of Se and In respectively. It is also necessary to control the ratio of Ga and S additions and to retain a certain portion of In to provide better properties of CIS films.

Abstract: Ti films of same thickness, and near normal deposition angle, and same deposition rate were deposited on glass substrates, at room temperature, under UHV conditions. Different annealing temperatures as 393K, 493K and 593K with uniform 8 cm3/sec, oxygen flow, were used for producing titanium oxide layers. Their nanostructures were determined by AFM and XRD methods. Roughness of the films changed due to annealing process. The gettering property of Ti and annealing temperature can play an important role in the nanostructure of the films.

Abstract: Nanocrystalline silicon film has become the research hit of today’ s P-V solar technology. It’s optical band gap was controlled through changing the grain size and crystalline volume fraction for the quanta dimension effect. The crystalline volume fraction in nc-Si:H is modulated by varying the hydrogen concentration in the silane plasma. Also, the crystallinity of the material increases with increasing hydrogen dilution ratio, the band tail energy width of the nc-Si:H concurrently decreases. Two sets of nc-Si:H solar cells were made with different layer thicknesss, their electronic and photonic bandgap, absorption coefficient, optical band gap, nanocrystalline grain size(D), and etc have been stuied. In addition, we discussed the relationship between the stress of nc-Si thin films and H2 ratio. At last nc-Si:H solar cells have been designed and prepared successfully in the optimized processing parameters.

Abstract: The AMPS-ID program is used to investigate optical and electrical properties of the solar cell of a-SiC:H/a-Si1-xGex:H/a-Si:H thin films. The short circuit current density, open circuit voltage, fill factor and conversion efficiency of the solar cell are investigated. For x=0.1, the conversion efficiency of the solar cell achieve maximum 9.19 % at the a-Si1-xGex:H thickness of 340 nm.

Abstract: Thin films of oxygen-conducting materials are expected to exhibit enhanced oxygen permeability, due to their reduced diffusion path. Two such materials, yttria-stabilised zirconia (YSZ) and ceria gadolinium oxide (CGO), were deposited onto anodic alumina substrates by electron beam evaporation of the parent materials. Continuous films 200-400 nm thick were characterised through SEM and XRD analysis. It was found that the substrate temperature during deposition strongly influenced the structure and stability of the films, with the original simple cubic structure being retained at deposition temperatures above 450 °C. Attempts to deposit thin films of a yttria-doped SrCoO_3-δ perovskite were unsuccessful, due to melting of the material during deposition and thermal diffusion into the substrate.

Abstract: We observe a large magneto-resistance in very thin Ba₂FeMoO₆ films of ~-12% at 10K, which is not significantly changed when thin NiFe/Ba₂FeMoO₆ bi-layers are made. This suggests that the magneto-resistance in both cases is dominated by inter-grain tunnelling in the Ba₂FeMoO₆ thin film. There is an anomalous peak in the resistance at ~300K in the bi-layer film that can not be easily explained. However, we know that the temperature where this peak occurs is close to the Ba₂FeMoO₆ Curie temperature.

Abstract: Sr-doped LaTiO₃ (SLTO) thin epitaxial films on LaAlO₃ (100) have been fabricated by the off-axis rf magnetron co-sputtering system. The dopant Sr²⁺ ions were expected substituting La³⁺ ions in the films to introduce the hole carriers. The X-ray diffraction shows that the [001] direction of the SLTO films is perpendicular to the substrate surface. The in-situ grown specimens were measured the temperature dependence of resistivity and the Hall coefficients to study the transport properties. The Hall measurements show that the carrier is electron for Sr-doping over 16%. The temperature dependence of the resistance shows that the n-type films are metallic and deviate from free electron gas model obviously. We found the behaviour could be well described by the small-polaron coherent motion model.

Abstract: In this paper, the indium tin oxide (ITO) thin films were prepared by a sol-gel spin coating method and then annealed under different temperatures (400, 500 and 550°C) in a mixture atmosphere of 3.75% H₂ with 96.25% N₂ gases. The microstructure, optical and electrical properties of the prepared films were investigated and discussed. The XRD patterns of the ITO thin films indicated the main peak of the (222) plane and showed a high degree of crystallinity with an increase of the annealing temperature. In addition, due to the pores existing in the prepared films, the optical and electrical properties of the prepared films are degraded through the sol-gel process. Thus, the best transmittance of 70.0 %in the visible wavelength region and the lowest resistivity of about 1.1×10^-2 Ω-cm were obtained when the prepared film was annealed at 550°C.

Abstract: Crystalline anatase TiO₂ thin films were obtained on glass substrates at 60°C, 75°C and 90°C, respectively, by liquid phase deposition (LPD) method without subsequent heat treatment. X-ray diffraction (XRD), atomic force microscopy (AFM) and UV-Vis spectrophotometer were used to characterize the as-synthesized TiO₂ thin films. The H₂ sensing properties of the TiO₂ thin films based sensors were investigated. The results show that the gas sensors signal Ra/Rg (Ra: resistance in air, Rg: resistance in a sample gas) decreases with the increasing deposition temperature. The TiO₂ thin films obtained at deposition temperature of 60°C exhibited the maximum H₂ gas response at 350°C, and the magnitude of the sensor signal and the response time for 500ppm H₂ was 1.25 and 17s, respectively.

Abstract: The inherent resiliency, hardness and relatively low friction coefficient of the fullerene-like (FL) allotrope of carbon nitride (CN_x) thin solid films give them potential in numerous tribological applications. In this work, we study the substitution of N with P to grow FL-CP_x to achieve better cross- and inter-linking of the graphene planes, improving thus the material’s mechanical and tribological properties. The CN_x and CP_x films have been synthesized by DC magnetron sputtering. HRTEM have shown the CP_x films exhibit a short range ordered structure with FL characteristics for substrate temperature of 300 °C and for a phosphorus content of 10-15 at.%. These films show better mechanical properties in terms of hardness and resiliency compared to those of the FL-CN_x films. The low water adsorption of the films is correlated to the theoretical prediction for low density of dangling bonds in both, CN_x and CP_x. First-principles calculations based on Density Functional Theory (DFT) were performed to provide additional insight on the structure and bonding in CN_x, CP_x, and a-C compounds.