Crystalline order in superfluid (3)He films

We predict an inhomogeneous phase of superfluid (3)He films in which translational symmetry is spontaneously broken in the plane of the film. This phase is energetically favored over a range of film thicknesses, D(c2)(T) < D < D(c1)(T), separating distinct homogeneous superfluid phases. The instability at the critical film thickness, D(c2) approximately 9 xi (T), is a single-mode instability generating striped phase order in the film. Numerical calculations of the order parameter and free energy indicate a second-order instability to a periodic lattice of degenerate B-like phases separated by domain walls at D(c1) approximately 13 xi (T).     

Long-range propagation of plasmon polaritons in a thin metal film on a one-dimensional photonic crystal surface

We present experimental results on ultralong-range surface plasmon polaritons, propagating in a thin metal film on a one-dimensional (1D) photonic crystal surface over a distance of several millimeters. This propagation length is about 2 orders of magnitude higher than the one in the ordinary Kretschmann configuration at the same optical frequency. We show that a long-range surface plasmon polaritons propagation may take place not only in a (quasi)symmetrical scheme, where a thin metal film is located between two media with (approximately) the same refraction index, but also in a scheme where the thin metal film is located between an appropriate 1D photonic crystal and an arbitrary (air, water, etc.) medium. The ultralong-range surface plasmon polaritons are potentially important for biosensors, plasmonics, and other applications.     

Spin Hall conductivity in three-dimensional topological insulator/normal insulator heterostructures

In the framework of an effective functional approach based on the k · p method, we study the combined effect of an interface potential and a thickness of a three-dimensional (3D) topological insulator (TI) thin film on the spin Hall conductivity in layered heterostructures comprising TI and normal insulator (NI) materials. We derive an effective two-dimensional (2D) Hamiltonian of a 3D TI thin film sandwiched between two NI slabs and define the applicability limits of approximations used. The energy gap and mass dispersion in the 2D Hamiltonian, originated from the hybridization between TI/NI interfacial bound electron states at the opposite boundaries of a TI film, are demonstrated to change sign with the TI film thickness and the interface potential strength. Finally, we argue that the spin Hall conductivity can efficiently be tuned varying the interface potential characteristics and TI film thickness.     

Interaction of silver atoms with iridium and with a two-dimensional graphite film on iridium: Adsorption,desorption, and dissolution

The initial stages in the interaction of silver with the (111)Ir surface and with a two-dimensional graphite film (2D GF) on (111)Ir were studied by high-resolution electron Auger spectroscopy in ultrahigh vacuum. The growth mechanisms of silver films and the desorption fluxes of Ag atoms were determined, and their desorption energies estimated. It was found that the Ag desorption fluxes from a 2D GF on Ir and from a thick silver film on the pure metal are similar and considerably (an order of magnitude) smaller than the sublimation fluxes from bulk silver at the same temperatures. The activation energy for desorption from a submonolayer film varies from 3.2 eV for coverage θ=1 to 3.7 eV at θ ～ 0. It was shown that silver atoms do not penetrate into the substrate bulk throughout the temperature range covered (300–1800 K).     

Image – Based “film” dosimetry in NILPRP SSDL

This paper presents the 1D, 2D & 3D dose distribution determination method using the Real Time Dosimetry (RTD) system in NILPRP Secondary Standard Dosimetry Laboratory (SSDL). MULTIDATA has extended the RTD system to perform traditional film dosimetry tasks directly on images. Image-based film dosimetry provided the benefits of traditional film analysis in a faster, more intuitive process for commissioning, quality assurance and beam data libraries in radiation beam applications.     

Scattering of an electromagnetic wave from a planar waveguide structure with a slightly 2D random surface

This paper deals with the scattering of an electromagnetic (EM) wave from a waveguide structure with a slightly rough surface. The waveguide structure is a dielectric film on a planar, perfectly conductive surface, and the top of the film is a two-dimensional (2D) homogeneous Gaussian random surface. The treatment is based on the stochastic functional theory where the random EM field is represented in terms of a Wiener - Hermite functional of the random surface. Numerical calculations show that enhanced backscattering and cross-polarization occur, but that no enhanced satellite peak appears for a 2D random surface, in contrast to the case of a 1D surface. The enhanced backscattering is caused by the interference of two double-scattering processes and is attributed to the existence of guided waves in the scattering structure.     

碳纳米管受限空间对共轭高分子聚(9,9-二辛基芴-2,7-二基)链段运动行为的影响

在纳米受限空间中,高分子往往会表现出与本体状态不同的性质,如异常的链段运动特性及晶相间转变行为等,这些性质对于研究和开发新型高分子材料具有重要的意义,因此针对受限环境下高分子的物理化学特性研究也一直是高分子界关注的焦点.本文通过化学气相沉积法制备垂直取向排列的多壁碳纳米管阵列,借助溶剂润湿–收缩法获得规整的高密度阵列结构,其取向排列的碳纳米管间隙形成了准一维的纳米受限空间,尺寸在5—50 nm尺度下可调.进一步将共轭高分子聚(9,9-二辛基芴-2,7-二基)(PFO)填充到碳管间隙的纳米空间中,制备PFO与取向多壁碳纳米管阵列复合膜.结果发现在碳纳米管形成的纳米受限空间中,PFO的链段热运动行为与本征态PFO薄膜相比受到了明显的抑制,不同晶型间转变速度大大减缓,提高了构象的热稳定性,同时取向排列的碳纳米管对PFO分子链取向排列分布具有明显的诱导作用,有利于获得高性能的PFO晶体.这种高密度取向排列的碳纳米管阵列结构未来可以用于制备优良发光性能及高稳定性的PFO光电器件.     

Domain shape relaxation and local viscosity in stratifying foam films

We studied the dynamics of two different types of domain shape relaxation in a stratifying foam film composed of an anionic polymer and cationic surfactant. Those films thin in stepwise fashion: circular domains of lower film thickness are formed, expand and coalesce until they cover the whole film surface. We found that the shape relaxation of coalescing domains is governed only by 2D dissipation, and the measurement of the time scales allows to determine the ratio between the driving force (line tension) and local film viscosity. Further, we analyzed the withdrawal of stripes and modeled it by a moving disc pulled by an external force. Here, 3D dissipation can not be neglected (Stokes paradox) and the equilibrium velocity depends logarithmically on the viscosity of the surrounding 3D air. The evaluation of both kinds of relaxation events yields the orders of magnitude of film viscosity and line tension. For the investigated system we found that the film viscosity is at least 30 times larger than the bulk viscosity, which can be explained by the local molecular ordering and strong interactions with film surfaces.     

Molecular mobility in polymer thin films

Fluorescence recovery after photobleaching was used to measure in-plane dye-probe diffusion coefficients, D, in thin films of monodisperse polystyrene supported on fused quartz substrates. The substrates were prepared with a high density of surface hydroxyl groups which interact favorably with repeat units of the polymer. The effects of temperature and film thickness were investigated, at temperatures above the bulk glass transition of the polymer, T(g), and in the range of film thicknesses from 1-10(2) times the radius of gyration (R(g)) of individual polymer molecules. As the film thickness decreases towards R(g) the value of D increases above the bulk values, with significant effects first appearing in films approximately 20R(g). In the thinnest films studied, about 4R(g), the values of D lie as much as two orders over bulk values. At the same time, the temperature dependence of D becomes much weaker than in bulk. Analysis by free volume theory indicates that apparent values of both T(g) and the thermal expansion coefficient for liquid state, alpha(L), decrease as the film thickness decreases. The possible effects of surface segregation of the dye probe are discussed.     

纳米晶粒生长的动力学蒙特卡罗模型

给出应用于纳米晶粒生长的动力学蒙特卡罗模型,并对模拟方法做了细致的讨论.作为一个应用实例,对薄膜生长做了分类模拟研究.结果显示,改变三维Ehrlich-Schwoebel势垒将导致薄膜生长过程中多层原子岛的结构相变.     

Fabrication of Au thin film gratings by pulsed laser interference

We report that one-dimensional (1D) and two-dimensional (2D) metal thin film gratings can be directly fabricated by interfering Nd-YAG pulsed laser beams (wavelength = 1064 nm, pulse width = 6 ns) incident from the backside of glass substrate. This process utilizes a laser-induced thermo-elastic force which plays a role to detach the film from the substrate. Micro-scale Au transmission gratings with a minimum feature size of 1 μm could be generated by interference-driven periodic detachment. The fabrication of tube-structured patterns as well as stripes was also possible by adjusting the pulse power and this is explained with the effect of film cohesion.     

使用铜源漏电极的非晶氧化铟锌薄膜晶体管的研究

为了实现氧化物薄膜晶体管(TFT)的低电阻布线,采用Cu作为氧化物TFT的源漏电极。通过优化成膜工艺制备了电阻率低至2.0μΩ·cm的Cu膜,分析了Cu膜的晶体结构、粘附性及其与a-IZO薄膜的界面,制备了以a-IZO为有源层和Cu膜的粘附层的TFT器件。结果表明:所制备的Cu膜呈多晶结构;引入a-IZO粘附层增强了Cu膜与衬底的粘附性;同时,Cu在a-IZO中的扩散得到了抑制。所制备的TFT的迁移率、亚阈值摆幅和阈值电压分别为12.9 cm2/(V·s)、0.28 V/dec和-0.6 V。     

高抗激光损伤阈值介孔SiO2 减反射膜

 用P123作模板剂,通过正硅酸乙酯的水解缩聚和溶剂蒸发自组装过程在K9玻璃上制备介孔SiO₂膜。应用FT-IR,XRD,N₂ 吸附-脱附,AFM和UV-Vis表征手段研究了薄膜的介孔结构和光学性能,并使用“R-on-1”模式,以Nd:YAG脉冲激光（9.2 ns, 1 064 nm）测试了薄膜的激光损伤阈值。结果表明:所镀制单层介孔SiO₂膜具有规整的2D p6 mm长周期结构,为SBA-15型,膜层表面比较平整（均方根粗糙度为2.923 nm）,在1 064 nm处的透过率为99.5%, 换算为激光脉宽为1 ns时,膜层的激光损伤阈值为21.6 J/cm²,显示出了较好的减反性能和抗激光损伤性能。     

一维光子晶体材料中的光学传输特性

研究了光在一维周期性介电材料中的传播特性,指出传统的高反膜只是光子晶体的一个特例,从而从光子晶体的角度对多层膜系的设计提出了一条新的思路,同时研究了材料的介电常数以及结构与高反带带宽之间的关系。最后通过在多层膜中引入掺杂（中间一层被另一种介质所代替）,得到第一能隙中掺杂模式的频率与掺杂材料的介电常数之间的对应关系,由此提出一种精确测量介质介电常数的方法。     

Crossover between 2D and 3D fluid dynamics in the diffusion of islands in ultrathin freely suspended smectic films

The Stokes paradox, that moving a disk at finite velocity through an infinite two-dimensional (2D) viscous fluid requires no force, leads, via the Einstein relation, to an infinite diffusion coefficient D for the disk. Saffman and Delbrück proposed that if the 2D fluid is a thin film immersed in a 3D viscous medium, then the film should behave as if it were of finite size, and D～ -ln(aη'), where a is the inclusion radius and η' is the viscosity of the 3D medium. By studying the Brownian motion of islands in freely suspended smectic liquid crystal films a few molecular layers thick, we verify this dependence using no free parameters, and confirm the subsequent prediction by Hughes, Pailthorpe, and White of a crossover to 3D Stokes-like behavior when the diffusing island is sufficiently large.     

高反射率硅基薄膜一维光子晶体的研究制备

采用射频等离子体增强化学气相沉积的方法,研究制备了一种基于硅基薄膜的高反射一维光子晶体。通过交替改变反应气体组分实现低折射率Si Ox层和高折射率a-Si层的交替层叠沉积,具有两种膜层介质折射率比大、反射率高、沉积时间短、工艺窗口宽等优点。采用5周期的Si Ox层与a-Si层构成的一维光子晶体(厚度分别为155 nm和55 nm),其禁带范围内(650~1 100 nm)的平均反射率达到99.1%,高于相同波长范围内Ag的平均反射率(96.3%)。     

Observation of triangular terraces and triangular craters of CaF2 film on Si(1 1 1) substrate

We have investigated the growth mode and surface morphology of CaF₂ film on Si(1 1 1)7×7 substrate by reflection high-energy electron diffraction (RHEED) using very weak electron beam and atomic force microscopy (AFM). It was found by RHEED intensity oscillation measurements and AFM observations that three-dimensional (3D) islands grow at RT; however, rather flat surface appears with two-dimensional (2D) islands around 300 °C. Especially, at high temperature of 700 °C, characteristic equilateral triangular terraces (or islands) with flat and wide shape grow with the tops directed toward [1 1 −2] of substrate Si(1 1 1). On the other hand, the desorption process of the CaF₂ film due to electron stimulated desorption (ESD) was also examined. It was found that the ESD process at 300 °C forms characteristic equilateral triangular craters on the film surface with the tops (or corners) directed toward [−1 −1 2] of substrate Si(1 1 1), provided that the film was grown at 700 °C.     

Hydrogen isotopic replacement and microstructure evolution in zirconium deuteride implanted by 150 keV protons

Zirconium tritiated(ZrT_x) is an alternative target material for deuteron–triton(D-T) reaction neutron generator. The isotopic replacement and microstructure evolution induced by hydrogen isotope implantation could significantly affect the performance of the target film. In this work, the zirconium deuteride film deposited on Mo/Si substrate was implanted by 150 ke V protons with fluence from 1×10~(16) to 1×10~(18) protons/cm~2. After implantation, the depth profiles of retained hydrogen(H) and deuterium(D) in these target films were analyzed by elastic recoil detection analysis(ERDA), and time of flight-secondary ion mass spectrometry(To F-SIMS). Additionally, the microstructure evolution was also observed by x-ray diffraction(XRD) and scanning electron microscope(SEM). The D concentration in the Zr Dx film decreased versus the proton implantation fluence. An analytical model was proposed to describe the hydrogen isotopic trapping and exchange as functions of incident protons fluence. Additionally, the XRD analysis revealed that no new phase was formed after proton implantation. Furthermore, circular flakings were observed on the ZrD_x surface from SEM images at fluence up to 1×10~(18) protons/cm~2, and this surface morphology was considered to associate with the hydrogen atoms congregation in Mo/Si boundary.     

Influence of thermocapillary effects on wave characteristics of the heated liquid film

Wave characteristics of the water film flow over a vertical plate with a heater were studied. Without a heat flux, data obtained perfectly coincide with results of other authors obtained for an isothermal liquid film. When heating the falling liquid, thermocapillary forces form the rivulets and thin film between them. It was found out that an increase in the heat flux causes a rise of the phase velocity and decreases the frequency of 3D waves. It is shown that in contrast to the known data for an isothermal liquid film, the average relative wave amplitude increases with a rise of dimensionless complex Re_loc/Ka _loc ^1/11 at relatively high heat flux densities in the interrivulet. The growth of wave amplitude under the action of thermocapillary forces was revealed in the interrivulet, what corresponds to calculations. The work was financially supported by the Russian Foundation for Basic Research (Grants Nos. 05-08-33325-a and 06-01-00360-a), Federal Target R&D Program (State contracts Nos. 02.438.11.7002 and NSh-6749.2006.8), and SB RAS (International interdisciplinary project No. 111).