氧化钛薄膜调控金属铜的表面等离子体共振特性研究

提出了一种利用氧化钛薄膜对金属铜薄膜表面等离子体共振特性调制的想法。实验中首先使用电子束蒸发制备一批同等厚度的氧化钛薄膜,再利用磁控溅射方法在氧化钛薄膜上沉积厚度为5～80 nm不等的金属铜薄膜。测试结果表明,氧化钛膜层对不同厚度的金属铜薄膜表面等离子体共振增强具有不同调制效果,金属铜薄膜厚度小于20 nm时,底层的氧化钛薄膜对Cu薄膜表面等离子体共振增强效果显著,且随着金属Cu膜层厚度增加表面等离子体共振峰发生蓝移,而当金属铜膜层的厚度超过20 nm时,共振增强效果因金属Cu薄膜消光能力的上升而开始减弱。     

Crystallization Kinetics of Lamellar Crystals Confined in Polymer Thin Films

We used dynamic Monte Carlo simulations to investigate the crystallization kinetics of flat-on lamellar polymer crystals in variable thickness films. We found that the growth rates linearly reduced with decreasing film thickness for the films thinner than a transition thickness d_t , while they were constant for the films thicker than d_t . Moreover, the mean stem lengths (crystal thickness) we calculated decreased with film thickness in a similar way to the growth rates, and the intramolecular crystallinities we calculated confirmed the film thickness dependence of the crytsal thickness. Besides, the crystal melting rates in thin films were calculated and increased with decreasing film thickness. We proposed a new interpretation on the film thickness dependence of the crystal growth rate in thin films, suggesting that it is dominated by the crystal thickness in terms of the driving force term (l–l _min) expressed by Sadler, rather than the chain mobility based on experiments. The crystal thickness can determine whether a crystal grows or melts in a thin film at a fixed temperature, indicating the reversibility between the crystal growth and melting.     

受约束纳米铅薄膜的过热

利用叠层轧制的方法制备出夹在铝中的纳米铅薄膜,厚度约20nm,部分铅薄膜与铝基体形成外延取向关系,对此纳米铅薄膜溶化的原位X射线研究表明,部分铅薄膜的熔化温度超过普遍块体材料,首次实现了金属薄膜的过热。     

Structure and electrical properties of InSb thin films prepared by plasmatic sputtering

This paper describes the apparatus for the plasmatic sputtering and preparation of InSb thin films. The structure and the dependence of the resistance of InSb films on the sputtering time at different temperatures are introduced. The dependences of the Hall constant, Hall mobility and electric conductivity of polycrystalline thin films on the film thickness is explained.     

Thin film stress measurement by instrumented optical fibre displacement sensor

Residual stress can adversely affect the mechanical, electronic, optical and magnetic properties of thin films. This work describes a simple stress measurement instrument based on the bending beam method together with a sensitive non-contact fibre optical displacement sensor. The fibre optical displacement sensor is interfaced to a computer and a Labview programme enables film stress to be determined from changes in the radius of curvature of the film-substrate system. The stress measurement instrument was tested for two different kinds of thin film, hard amorphous carbon nitride (CN) and soft copper (Cu) films on silicon substrates deposited by RF magnetron sputtering. Residual stress developed in 500 nm thick CN thin films deposited at substrate temperatures in the range 50-550 °C was examined and it was found that stress in CN films decreased from 0.83 to 0.44 GPa compressive with increase of substrate temperature. Residual stress was found to be tensile (121 MPa) for Cu films of thickness 1500 nm deposited at room temperature.     

Substrate and chain size dependence of near surface dynamics of glassy polymers

We use nanohole relaxation to study the surface relaxation of films of glassy isotactic poly (methyl methacrylate) (i-PMMA) films. These measurements allow us to obtain the time dependent relaxation function at a number of different sample temperatures for the first 2-3 nm of the free surface in a system often used as a model system for the effect of the substrate on thin film dynamics. The surface is observed to relax at temperatures up to 42 K below the bulk Tg value, even on systems where the thin film Tg is known to be greater than the bulk value. We are able to determine the range over which the substrate directly affects the free surface relaxation, and determine a surprisingly large (Mw independent) limiting thickness of approximately 180 nm where the free surface relaxation is not affected by the substrate. For thick films (h>200 nm) we find an unexpected linear Mw dependence of the near surface relaxation time.     

Thermodynamic approach to the size dependence of the melting temperatures of films

The size dependence of melting temperature T _m of metallic films (tin and copper) on different substrates, including amorphous carbon and another refractory metal (i.e., the dependence of T _m on film thickness h) is investigated. It is found that the effect of the interfacial boundary can result in the growth of T _m for thin metallic films on carbon substrates with a reduction in film thickness h. For a system with a metallic film on a metallic substrate, the size dependence of T _m is less pronounced and T _m falls with a reduction in h.     

The effects of post-thermal annealing on the optical parameters of indium-doped ZnO thin films

Indium-doped ZnO thin films are deposited on quartz glass slides by RF magnetron sputtering at ambient temper- ature. The as-deposited films are annealed at different temperatures from 400 C to 800 C in air for 1 h. Transmittance spectra are used to determine the optical parameters and the thicknesses of the films before and after annealing using a nonlinear programming method, and the effects of the annealing temperatures on the optical parameters and the thickness are investigated. The optical band gap is determined from the absorption coefficient. The calculated results show that the film thickness and optical parameters both increase first and then decrease with increasing annealing temperature from 400 C to 800 C. The band gap of the as-deposited ZnO:In thin film is 3.28 eV, and it decreases to 3.17 eV after annealing at 400 C. Then the band gap increases from 3.17 eV to 3.23 eV with increasing annealing temperature from 400 C to 800 C.     

Selective electroplating of copper lines on pre-patterned tantalum oxide thin films

Direct selective metal deposition on semiconductors is of interest to electronic device technology, in particular for interconnects and Schottky devices. In this study, we investigate selective copper electrodeposition on patterned tantalum oxide thin films. Cyclic voltammetry studies show that thick tantalum oxide thin films have insulating properties while oxide films thinner than a critical value are semiconductors. Copper films electrodeposited on tantalum oxide thin films are known to form Schottky contacts. We demonstrate the formation of copper patterns on pre-patterned tantalum oxide films by a simple process: an insulating tantalum oxide film was grown electrochemically, the film was then mechanically scratched followed by mild oxidation to produce a thin tantalum oxide film inside the scratch. Based on the differential behavior of thin and thick tantalum oxide films, metal lines were electrodeposited selectively under formation of Schottky junctions. The process demonstrated in this paper is compatible to standard processes for semiconductor device fabrication while permitting flexible prototyping for research at small scales.     

Investigation of material properties of thin copper films through finite element modelling of microindentation test

Technology processes of thin metal films deposition are entailed with changes in material’s microstructure. As a result, deposited films often are characterized with material properties, which are different from these of the original bulk material. Determination of these material characteristics is of big importance for practice. In the present work the material properties of thin bright copper film with known depth were investigated. The film was deposited electrochemically over substratum composed of metallurgic brass alloy (CuZn36). Based on the results from microindentation test the load-displacement curve is obtained after the indenter is unloaded and the imprint diameter is measured. Consequently the process of indentation was modelled numerically. The numerical simulation is based on the finite element model of the indentation process. As a result of the simulation the load-displacement curve was obtained numerically for a certain set of material parameters. The trial-error approach is applied to find most appropriate set which fit the experimental load-displacement curve. At the end results, which were obtained through numerical simulation give good coincidence with the experiment. Therefore the proposed method can be successfully applied for identification of material parameters of the accepted model. The proposed trial-error approach is appropriate for investigation of thin films with known thickness, deposited on a substrate with known material characteristics.     

Non-monotonic dependence of temperature of Au nanometer films dissociation into droplets on their thickness on Al2O3 surface

The process of melting with consequent disintegration into droplets of various thickness Au thin films has been studied. An unexpected character of the melting–disintegration temperature dependence on thin-film thickness has been found: a reduction of the process temperature has been observed with thickness in the range from 100 to 20 nm; however, the disintegration temperature starts to increase for Au film thicknesses lower than 20 nm. It is supposed that the observed non-monotonic behavior of the process temperature is caused by the influence of the substrate interaction with the film, resulting in an entropy change of the system.     

Glass transitions and dynamics in thin polymer films: dielectric relaxation of thin films of polystyrene

The glass transition temperature T(g) and the temperature T(alpha) corresponding to the peak in the dielectric loss due to the alpha process have been simultaneously determined as functions of film thickness d through dielectric measurements for polystyrene thin films supported on glass substrate. The dielectric loss peaks have also been investigated as functions of frequency for a given temperature. A decrease in T(g) was observed with decreasing film thickness, while T(alpha) was found to remain almost constant for d>d(c) and to decrease drastically with decreasing d for d相似文献   

Fabrication of graphene and graphite films on the Ni(111) surface

The growth of graphene and graphite films on nickel surface under conditions for ultrahigh-vacuum carburization and subsequent annealing is studied at film thicknesses ranging from a single layer to ≈1000 layers. The cooling of nickel carburized at a temperature of 900–1500 K leads to the growth of graphene and thin graphite films the thickness of which depends on the carburization temperature and the growth temperature of the films. Dissolution of nickel with graphite film in diluted sulfuric acid makes it possible to separate the film from the sample. The graphite film thickness amounts to ?0.4 µm at carburization and growth temperatures of 1500 and 1100 K, respectively.     

Recombination at mixed-valence impurity centers in PbTe(Ga) epitaxial layers

The photoconductivity kinetics in PbTe(Ga) epitaxial films prepared by the hot-wall method is studied. The recombination of nonequilibrium photoexcited electrons at low temperatures was found to proceed in two stages, with a period of relatively fast relaxation followed by delayed photoconductivity. The temperature at which delayed photoconductivity appears increases with decreasing film thickness. The relaxation rate over the period of fast relaxation depends on film thickness and is the lowest in the thinnest layers. In semi-insulating films, photoconductivity is always positive, whereas in samples with lower electrical resistivity positive and negative photoconductivities are observed to coexist. The data obtained are discussed in terms of a model in which the impurity gallium atom can be in more than one charged state.     

基底温度对电子束蒸发制备氧化铝薄膜的影响

为了考察基底温度对氧化铝薄膜折射率以及沉积厚度的影响情况,在不同基底温度环境下,通过离子辅助电子束蒸发方式,在玻璃基底上制备了同一Tooling因子条件下所监测到相同厚度的Al2O3薄膜,利用分光光度计测量光谱透过率,依据光学薄膜相关理论,计算了基底温度在25℃～300℃范围内获得的膜层实际物理厚度为275.611 nm～348.447 nm,以及膜层折射率的变化。通过对实验结果的数值计算和曲线模拟,给出了基底温度对于薄膜的折射率和实际厚度的影响情况。     

Surface roughness modulated resistivity in copper thin films

The surfaces of metallic thin films are never flat. The resistivity in thin films is very different from that in bulk because of the unavoidable rough surfaces. In this study, we apply a quantum-mechanical method to study the resistivity in metallic thin films. The resulting resistivity formula for metallic thin films merely involves two parameters: bulk relaxation time and surface roughness. We use the formula to fit a large number of experimental data sets for copper thin films obtained using different growing methods. With an additional tuning parameter for calibrating the film thickness, the quantum formula can provide a universal fitting to most data with a satisfactory precision, regardless of their growing methods or data source.     

Ion crater healing and variable temperature ellipsometry as complementary probes for the glass transition in thin polymer films

Poly(methyl methacrylate) (PMMA) thin films of various tacticity and thickness were bombarded at grazing angles by 20 MeV Au ions at different temperatures. The shape of the tracks was investigated by scanning force microscopy (SFM) after annealing for various time at different temperatures and constant quenching rate. The thickness dependent glass transition temperature, T(g)(h), was estimated from the temperature of relaxation of ion-caused nanodeformations in the films. T(g)(h) obtained from the thermal healing of the holes and hillocks is found in good agreement with the one determined by variable temperature ellipsometry for PMMA film thickness of 80 nm and corresponds to the T(g) of each bulk PMMA stereoisomer. Below this thickness, some significant divergences are observed between the T(g) measured by the two techniques. We propose that the healing of ion crater hillock and the kink in the thermal expansion arise from the different nature of chains motions which are perturbed to different extents according to the main polymer chain preferential orientation in the thin film. This can be tentatively interpreted by a so-called "anisotropic" character of the glass transition.     

Chemically deposited copper oxide thin films: structural, optical and electrical characteristics

Thin films of copper oxide with thickness ranging from 0.05–0.45 μm were deposited on microscope glass slides by successively dipping them for 20 s each in a solution of 1 M NaOH and then in a solution of copper complex. Temperature of the NaOH solution was varied from 50–90°C, while that of the copper solution was maintained at room temperature. X-ray diffraction patterns showed that the films, as prepared, are of cuprite structure with composition Cu₂O. Annealing the films in air at 350°C converts these films to CuO. This conversion is accompanied by a shift in the optical band gap from 2.1 eV (direct) to 1.75 eV (direct). The films show p-type conductivity, 5×10⁻⁴ Ω⁻¹ cm⁻¹ for a film of thickness 0.15 μm. Electrical conductivity of this film increases by a factor of 3 when illuminated with 1 kW m⁻² tungsten halogen radiation. Annealing in a nitrogen atmosphere at temperatures up to 400°C does not change the composition of the films. However, the conductivity in the dark as well as the photoconductivity of the film increases by an order of magnitude. The electrical conductivity of the CuO thin films produced by air annealing at 400°C, is high, 7×10⁻³ Ω⁻¹ cm⁻¹. These films are also photoconductive.     

缓冲层Ta对FePt薄膜L10有序相转变及矫顽力的影响

制备了Ta/FePt/C系列多层膜，研究了样品在不同温度退火后的磁特性和微结构.实验结果表明，不同厚度的Ta缓冲层具有不同的微结构特征，显著影响FePt层的L1₀有序相的形成及相应的矫顽力.当Ta缓冲层较薄，Ta层为非晶态，且较为粗糙，由此使FePt在界面处产生较多的缺陷并导致较高密度的晶界，在退火过程中，受束缚相对较弱的非晶态的Ta原子比较容易沿FePt的缺陷和晶界处向FePt层扩散，使FePt在相变过程中产生的应力比较容易释放，同时，Ta在扩散过程中产生的缺陷，降低了FePt有序 关键词： FePt薄膜 0相')" href="#">L1₀相 原子扩散