Papers by Keyword: Ion Beam Sputtering

Abstract: The effect of the formation and heat treatment modes of silicon-carbon coatings deposited by ion-beam sputtering of silicon carbide on their morphology, chemical and phase composition is determined. It has been established that an increase in the power of the ion source from 432 W to 738 W leads to a decrease in the sp³/sp² phase ratio by 1.7 times and an increase in the ratio of Si-C/Si-O bonds by 1.9 times. It is shown that doping of carbon coatings with silicon carbide increases their heat resistance.

Abstract: Hafnium films were prepared on the molybdenum substrate at room temperature by ion beam assisted deposition (IBAD) and post-annealing was conducted to know their status under high temperature. The structure and composition of Hf coatings were confirmed by XRD, STEM and EDX, respectively. The adhesion strength between the coating and the substrate was evaluated by a nanoscratch tester. The results show that some dilution occurs at the coating/substrate interface and that Mo combines with Hf to form a HfMo₂ alloy after high temperature annealing. The adhesive force of the Hf coating was increased from 120 mN to 160 mN after annealing.

Abstract: In this study, hydroxyapatite (HA) coatings on Ti6Al4V substrate were deposited using an ion beam sputtering technique. Owing to its medical applications, the crystalline phases present in the HA must be controlled. This study investigated the effect of post-deposition heat treatment at different temperatures and evaluated the microstructure of the HA coatings and their behaviours in simulated body fluid (SBF). The post-deposition treatment of the as-deposited samples was carried out in an air-circulated furnace at a temperature between 300 ⁰C and 600 ⁰C. The XRD patterns reveal that the minimum temperature to transform the HA coating from amorphous to crystalline phase is 400 ⁰C. A higher temperature at 600 ⁰C leads to a growth of the crystalline HA phases. Fourier transform infrared spectroscopy (FTIR) measurements show the existence of hydroxyl and PO-bonds in all coatings and the amounts varied with temperature. Atomic Force Microscopy (AFM) study suggests that the nanostructured crystalline HA starts to grow at 400 ⁰C and becomes more obvious at a higher temperature of 600 ⁰C. The simulated body fluid (SBF) test reveals that better apatite formation with post deposition heat treatment at 600 ⁰C would potentially enhance the formation of new bone (osseointegration).

Abstract: Pure Ni coating and multi-layered Ni-P coatings were deposited on sintered NdFeB magnets by ion beam sputtering and electroless plating to improve the corrosion resistance of magnets, respectively. The structure and preferred growth orientation, surface morphology, the adhesive strength between coatings and magnets, and corrosion properties of samples were investigated by XRD, SEM, high-low temperature shock test and potentiodynamic polarization curves, respectively. It was found that electroless Ni-P coatings are amorphous with nodules distributed, Ni coating deposited by ion beam sputtering is crystalline and spherical Ni grains are densely packed. Ni coating deposited by ion beam sputtering can provide better protection for sintered NdFeB than that of electroless Ni-P coating.

Abstract: A series of double-layer Ge/Si quantum dots are prepared by ion beam sputtering deposition (IBSD) on Si (100) substrates. The influences of deposition temperature and thickness of Si spacer-layer on the microstructure of double-layer Ge/Si quantum dots were characterized by using Atomic force microscopy (AFM) and Raman spectra technique. The results indicate that the density of the second layer islands firstly increases and then decreases with increasing the growth temperature of Si spacer-layers. In addition, increasing the thickness of Si spacer-layer, the islands merger phenomenon disappears. When the deposition thickness is larger than 40 nm, the islands on the upper-layer show the same features with the buried islands. The mechanism of three-factor-interactions of nanoislands is proposed to explain these phenomena, and our results can be used as a guidance to obtain optimum IBSD growth process for Ge/Si quantum-dot superlattices.

Abstract: Cu-doped CdS thin film has been successfully deposited by ion-beam sputtering deposition. The structural, morphology, optical and electrical properties of as-deposited and annealed Cu-doped CdS thin films were investigated. The heavily Cu-doped CdS films annealed at 400 °C was demonstrated to be improved in structural, morphology, electrical and optical properties. X-ray diffraction (XRD) analysis indicated the formation of polycrystalline CdS film with the structure of hexagonal wurtzite phase. No distinct impurity of Cu and Cu-S phase was detected in Cu-doped CdS thin films. Atomic force microscopy (AFM) revealed that the grain size was increased after annealed. Optical transmission and absorption spectroscopy measurement revealed a high absorption and energy band gap was of about 2.40 eV. The CdS thin film was of p-type conductivity and the resistivity was found to be 1.28×10^-1Ωcm.

Abstract: Significant progress has been made in thermoelectric materials during the last decades and it is found that thermoelectric thin film materials have high thermoelectric conversion efficiency. ZnO based thermoelectric materials, such as ZnO:Al (AZO), are considered as the most promising oxide materials for high-temperature, nontoxic and low-cost thermoelectric application. In this work, the effects of annealing temperature on the thermoelectric properties of AZO thin films prepared by direct current magnetron sputtering were investigated. The results indicate that the Seebeck coefficient of AZO thin films increases and the resistivity decreases as increasing of annealing temperature. Among the prepared AZO films in this work, the maximum absolute value of Seebeck coefficient is 460 μV/K and the minimum resistivity is 3.25×10^-4 Ω·m. The sample annealed at 773 K has a maximum power factor value of 1.46×10^-4 W/mK² at 620 K with a moderate Seebeck coefficient of-355 μV/K and a electrical conductivity of 1.16×10³ S/m.

Abstract: Abstract. Microstructural, optical and mechanical properties of oxide and fluoride films are examined. Superior optical quality, durability and environmental stability are achieved for oxides deposited by ion assist reactive ion beam sputtering and thermal evaporation. The materials and deposition techniques are discussed with regards to manufacturing of optical interference filters for near-UV – mid-IR wavelengths. High performance of thin film materials and optical filters is demonstrated.

Abstract: The combinatorial material library approach is an excellent innovation for inorganic functional material research, and it can discover and screen new materials efficiently. In this paper, it is used to quickly find and improve Tb₃₊ activated gadolinium aluminate perovskite phosphors (Gd_1-x-yAlO₃: Tb_x, RE_y, RE ion vary among Ce^3+,4+, Dy³⁺, abbreviate as GAP:Tb,RE). Under UV light excitation, Gd_1-x-yAlO₃: Tb_x, RE_y gradational combinatorial library indentifies the “lead” green luminescent compound as GAP:Tb_0.1 from all the GAP:Tb_x (x=0.05~0.15) candidates in a quick way. Then the relationship between sensitizers and activators can be also mapped out quickly, that Dy³⁺, is a good sensitizer for Tb³⁺,activator while Ce^3+,4+ is not a suitable one. The photoluminescent excitation (PLE) and photoluminescent emission (PL) spectral indicate the resonance energy transfer between the activator and sensitizer must have happened, which leads to Ce^3+,4+ co-doping decrease Tb³⁺ green luminescence（⁵D₄→⁷F₅，544nm） while Dy³⁺ co-doping increase green luminescence. The candidates in the library are prepared in powder form by nitric-citric method for more detailed characterization. All the screening results, obtained from the combinational library, are coherent with the powder phosphor experiments.

Abstract: Antimony (Sb) and zinc (Zn) bilayer was sputter-deposited at room temperature with various Zn contents by ion-beam sputtering and transformed into Antimony zinc after post thermal annealed at 573K for 60 min. A power factor of 6.18×10-4 W/mK2 at 473 K has been obtained when the sputtering time of the Zn was 20 minutes. The maximum Seebeck coefficient is 42.0 μVK-1. Composition analysis shows that the compound of SbZn is achieved and the small Seebeck coefficient is due to the deviation of stoichiometric.