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Abstract

Nondoped BiFeO3 (BFO) and doped Bi0.9La0.1Fe0.9Mn0.1O3 (BLFMO) thin films (d = 200–350 nm) were grown at 650–750 °C by RF sputtering on Si and SrTiO3(100), coated by conductive LaNiO3 films and La2/3Ca1/3MnO3/SrRuO3 bilayers. The complex dielectric permittivity of the films was measured at room temperature in the frequency range from 10 MHz to 10 GHz using parallel plate capacitor structures. Dielectric properties of the polycrystalline BFO films were compared with those of the epitaxial quality BLFMO films, and it was seen that the latter has better microwave performance than the former. The dielectric losses were below 0.05 at 1 GHz frequency, which may be acceptable for microwave applications.

, 2010, pp. 7366–7371. [13] I. Caretti, M. Yuste, R. Torres, O. Sánchez, I. Jiménez, and R. Escobar Galindo, “Coordination chemistry of titanium and zinc Ti (1−x) Zn 2 x O 2 (0 ≤ x ≤ 1) ultrathin films grown by DC reactive magnetron sputtering”, RSC Advances , vol. 2, 2012, pp. 2696-2699. [14] L’. Vančo, Slovak University of Technology, Bratislava, personal communication, 2016. [15] R. Medlín, P. Šutta, M. Netrvalová and P. Novák, “Investigation of structural changes of ZnO:Ti thin films prepared by RF sputtering”, European Microscopy Congress 2016: Proceedings

Abstract

The present work reports the fabrication of p-Si/SiO2 /TiO2 and p-Si/SiO2 /TiO2 /ZnO heterostructures deposited by RF sputtering on p-Si substrate. The structural properties of the heterostructures were characterized by X-ray reflectivity and SIMS depth profiling. The electrical and optical properties of the heterostructures were investigated by I − V, C-V measurements and VIS spectroscopy, respectively. The measurements reveal that I − V characteristics in dark show semiconductor-insulator-semiconductor (SIS) structure properties. The I − V characteristics under illumination exhibit changes with significant increase of photocurrent due to photoassisted tunnelling and injection through SiO2 /TiO2 interlayer.

Abstract

Copper (Cu) and nickel (Ni) nanoparticles have been grown simultaneously on glass and silicon substrates by RF sputtering method to form three Cu/Ni nanocomposites at different deposition times. The existence of Cu and Ni peaks in the X-ray diffraction (XRD) profiles confirms the crystalline structure of samples with Cu and Ni atomic content which have also been characterized by Rutherford backscattering (RBS) method. Moreover, the structural and morphological properties of the prepared nanocomposites have been compared with respect to their morphologies by means of atomic force microscopy (AFM) analysis. In order to compare the surface roughness over different spatial frequency ranges and evaluate surface quality, power spectral density (PSD) of each sample has been extracted from AFM data and also, the experimental and theoretical results have been compared. The fractal nature of these nanocomposites has been finally discussed.

Abstract

Dynamical mechanical analysis yields information about the mechanical properties of a material as a function of deforming factors, such as temperature, oscillating stress and strain amplitudes. GaAs and Mn-doped GaAs at varied levels, used in making electronic devices, suffer from damage due to changes in environmental temperatures. This is a defective factor experienced during winter and summer seasons. Hence, there was a need to establish the best amount of manganese to be doped in GaAs so as to obtain a mechanically stable spin injector material to make electronic devices. Mechanical properties of Ga1-xMnxAs spin injector were studied in relation to temperatures above room temperature (25 °C). Here, creep compliance, Young’s moduli and creep recovery for all studied samples with different manganese doping levels (MDLs) were determined using DMA 2980 Instrument from TA instruments Inc. The study was conducted using displace-recover programme on DMA creep mode with a single cantilever clamp. The samples were prepared using RF sputtering techniques. From the creep compliance study it was found that MDL of 10 % was appropriate at 30 °C and 40 °C. The data obtained can be useful to the spintronic and electronic device engineers in designing the appropriate devices to use at 30 °C and above or equal to 40 °C.

. Rigsbee, “Metastable tetragonal zirconia formation and transformation in reactively sputter deposited zirconia coatings”, Surface and Coatings Technology , vol. 135, pp. 109–117, 2001. [12] J. Park, J. K. Heo, Y.-C. Kang, “The properties of RF sputtered zirconium oxide thin films at different plasma gas ratio”, Bull Korean Chem Soc. , vol. 31, pp. 397, 2010. [13] C. Ma, F. Lapostolle, P. Briois, Q. Zhang, “Effect of O 2 gas partial pressure on structures and dielectric characteristics of rf sputtered ZrO 2 thin films”, Applied surface science , vol. 253, pp. 8718

R eferences [1] K. Izumi, D. Masanobu, H. Ariyoshi, “Properties of Zirconium Nitride Film Resistors Deposited by Reactive RF Sputtering”, Parts Hybrids Packaging PHP-11 , pp. 105, 1975. [2] D. Wu, Z. Zhang, W. Fu, X. Fan, H. Guo, “Structure, electrical and chemical properties of zirconium nitride films deposited by dc reactive magnetron sputtering”, Appl. Phys. A , vol. 64, pp. 593, 1997. [3] S. Niyomsoan, S., W. Grant, D. L. Olson, B. Mishra, “Variation of color in titanium and zirconium nitride decorative thin films”, Thin Solid Films , vol. 415, pp. 187

. Ann. N.Y. Acad. Sci ., 1006, 104–121. DOI: 10.1196/annals.1292.007. 46. Sreenivas, K., Rao, T. & Mansingh, A. (1985). Preparation and characterization of rf sputtered indium tin oxide films. J. Appl. Phys ., 57, 384–392. https://doi.org/10.1063/1.335481 . 47. Shigesato, Y., Takaki, S. & Haranoh, T. (1992). Electrical and structural properties of low resistivity tin-doped indium oxide films. J. Appl. Phys ., 71, 3356–3364. https://doi.org/10.1063/1.350931 . 48. Rey, J.F.Q., Plivelic, T.S., Rocha, R.A., Tadokoro, S.K., Torriani, I. & Muccillo, E.N.S. (2005

) coated glass substrates employing DC magnetron sputtering technique. It was observed that the morphology and roughness of the deposited coatings were significantly influenced by the deposition parameters. Surface roughness and surface energy were enhanced by high deposition pressure [4] . Similarly, single SiO 2 layer and double SiO 2 /TiO 2 layer of AR coatings were deposited on silicon substrates to enhance the PCE by employing RF sputtering technique. Electrical and optical characteristics of prepared specimens were examined. Lately, an improved PCE and reduced

prepared by RF sputtering, spin coating and spray pyrolysis, respectively. An increase of 18 meV in optical band gap of Fe doped films prepared by sol-gel spin coating method was reported by Xu et al. [ 13 ]. Parra-Polomino et al. [ 14 ] also reported an increase, of 340 meV, in optical band gap of iron doped nanocrystals prepared by chemical route. n-type semiconducting metal oxides can also be used for gas sensing as they were able to exhibit variation in some electrical parameters, viz. resistance and capacitance of the film upon adsorption of gases. Also, metal