This PDF file contains the front matter associated with SPIE Proceedings Volume 7766, including the Title Page, Copyright information, Table of Contents, Introduction if any, and the Conference Committee listing.

This work reports on the controlled growth of well-aligned ZnO micro/nanorod arrays at low temperature on GaN substrates. The influence of GaN surface morphology and doping on the growth of ZnO rods via hydrothermal method is studied. The structural properties of ZnO rods are investigated using field-emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD). The grown ZnO rods show preferred orientation along the c-axis and are well aligned with high aspect ratios. For precisely controlling the formation of well-aligned ZnO micro/nanorod arrays, a two-dimensional periodic polymer aperture arrays on top of GaN is also utilized for selective growth of ZnO rods. The size of ZnO rods is controlled over a considerably wide size range from 130 nm up to 3.5 μm in diameter by tuning the aperture size of the pattern and solution concentrations. It is observed that the ZnO rods are not grown directly through the aperture template. In addition, the size of ZnO rods is found to be dependent on the geometry of polymer aperture arrays. The detailed growth behavior is characterized and analyzed. This work provides a route to achieve the low-temperature heteroepitaxy of ZnO mirco/nanorod arrays on GaN, which can be very useful for many optoelectronics applications, especially for light emitting diodes.

ZnO has great potential in a wide range of applications such as microelectronics, optoelectronics, and sensors. Hydrothermal method has proven to be an effective method for the growth of nanostructured materials. Vertically aligned ZnO nanorods were grown on various substrates such as glass and Si by low temperature hydrothermal method using ZnO as the seed layer. The thin seed layer on various substrates was deposited by RF magnetron sputtering. The morphology of the ZnO nanorods can be tuned by varying the sputtering conditions and hydrothermal parameters. Scanning electron microscopy images confirm the formation of vertically aligned nanorods and XRD pattern shows the formation of wurtzite structure of ZnO. The sharp (0002) peak in the XRD spectra indicates that the synthesized nanorods are single crystalline, grown along the [0001] direction. These ZnO nanostructures can be considered as a potential candidate for sensor and nanowire transistor applications.

Fingerprint visualization obtained from physical evidence taken from crime scenes for subsequent comparison typically requires the use of physical and chemical techniques. One physical technique to visualize or develop sebaceous fingerprints on various surfaces employs the deposition of metals such as gold and zinc thereon. We have developed a different vacuum technology: the conformal-evaporated-film-by-rotation technique to deposit dense columnar thin films (CTFs) on latent fingerprints on different types of surfaces. Sample fingerprints, acting as nonplanar substrates, deposited on different surfaces were placed in a vacuum chamber with the fingerprint side facing a boat containing an evaporant material such as chalcogenide glass. Thermal evaporation of the solid material led to the formation of a dense CTF on the fingerprint, thereby capturing the topographical texture with high resolution. Our results show that it is possible to acquire the topology of latent fingerprints on non-porous surfaces. Additionally, deposition of CTFs on overlapping fingerprints suggested ours may be a technique for elucidating the sequence of deposition of the fingerprints at the scene.

In this work, a simple and high efficient way to change the polarization state is proposed. A broadband polarization conversion (PC) filter based on a prism coupling system (BK7 prism/anisotropic film/air) is investigated. The anisotropic SiO₂ thin film prepared by glancing angle deposition is a columnar thin film with near uniaxial property. At a certain angle range around 51.5. over the critical angle, there exists an enhanced PC reflection when the plane of incidence is vertical to the deposition plane. The reason of polarization conversion (PC) reflectance in an anisotropic SiO₂ thin film (n1', n2', n3') = (1.260, 1.216, 1.215) is analyzed and interpreted in the prism-coupling system (prism/ SiO₂ thin film /air). In order to achieve the broadband PC reflectance spectrum, a three-layered structure (isotropic MgF₂ thin film/ anisotropic SiO₂ thin film/ isotropic MgF₂ thin film) was arranged. The three-layered structure thin film is investigated optimum ability as broadband polarization device.

We theoretically propose two types of antireflection (AR) coatings for metals. One type consists of a single layer of a dielectric material having a high refractive index. The other type consists of bilayers of absorptive and dielectric materials that are used in order to reduce the reflectance of high reflectivity metals such as Al in the visible region. The bilayered AR concept has been applied to reduce the reflectance of wire grid (WG) polarizers made of Al. An FeSi2 layer, which serves as an absorptive layer, has been deposited by the glancing angle deposition technique immediately on the top of Al wires covered with a thin SiO2 layer, which serves as a gap layer. For the optimum combination of the thicknesses of FeSi2 and SiO2, the reflectance reduces to lower than a few percent independent of the polarization, whereas the transmission polarization properties remain favorable. Because low reflectivity WG polarizers are completely composed of inorganic materials, they are useful for applications requiring thermal durability, such as liquid crystal projection displays.

Various Ag and Au nanostructured films such as Ag nanoparticle (NP) films, Au NP films, and Au NP/TiO2/Au NP sandwich structures are fabricated by oblique angle deposition (OAD) and glancing angle deposition (GLAD) methods. Their optical absorbance properties and localized surface plasmon resonance (LSPR) have been studied systematically for samples prepared at different deposition conditions. Under the same deposition conditions, the Ag or Au NP substrates produced by GLAD method are more uniform and reproducible. The LSPR wavelength of Ag or Au NP substrates can be easily tuned by changing the film thickness, the deposition angle, and the coating of dielectric layer. The ability of the nanoparticle films as a chemical and biological biosensor has been explored by sensing the biomolecule NeutrAvidin and the bacterium Salmonella. Those NP films are very sensitive to chemical detection but are insensitive for bacteria detection. Based on Mie theory and effective medium theory, this is due to the small contact area between the nanoparticle and the bacteria, and the short range interaction of the local electric field. Our results demonstrate that shadowing based growth is a very versatile fabrication technique to produce reproducible and finetuned LSPR substrates.

In this work, the chevronic films composed of silver nanorods are fabricated using glancing angle deposition (GLAD). The chevronic structure is grown by bidepositing opposite nanorods sequentially: the substrate is oriented at the polar angle Φ=0 deg (about the substrate's normal) for the bottom rods and Φ180 deg for the top rods. When the applied electric field is parallel to the plane Φ= deg, the induced magnetic dipole moment between nanorods leads to a negative real part of the equivalent permeability. The equivalent refractive indices, the equivalent permittivities and the equivalent permeabilities of chevronic films with thickness 230 ± 5 nm for p-polarized light are measured by walk-off interferometer. The equivalent permeabilities of chevronic films with lengths of top rods 291 nm, 409 and 509 nm and bottom rods 512 nm, 378 nm and 301 nm are measured to be -2.406+0.443 i, -3.870+2.109 i and -2.126+0.904 i at the wavelength of 639 nm, respectively. The shape affects the real part of the equivalent permeability significantly. When the length of the top rods is longer than that of the bottom rods, the magnetic dipole moment between nanorods is suppressed and the quantity of the equivalent permeability becomes small. The real part of equivalent permeability of the chevronic film is related to the lengths of top and bottom nanorods.

Semi-continuous silver films (SSFs) with different filling fractions are papered on BK7 substrate in electron beam evaporation system. The microstructural and optical properties are studied near the percolation threshold. From morphological evolution, the transition from nanograins, through nanoclusters to near uniform film can be observed in SEM images. As the filling fraction increasing, the transmittance variation over the wavelength range from 800 nm to 2400 nm is changed from an increasing behavior to a decreasing behavior. The spectral transmittance and reflectance of the SSFs are essentially constant near the percolation threshold in the infrared. The thickness of growing MgF₂ film is measured at the wavelength of 532 nm by optical monitoring and stopped coating at the crest of the curve in monitor chart. Equivalent admittance of a semi-continuous silver film at the MgF₂/SSF can be retrieved using characteristic matrix. With different filling fraction, the variations of equivalent admittance of a semi-continuous silver film at the MgF₂/SSF are discussed.

Stable dispersion of colloidal indium tin oxide nanoparticles was prepared by using indium tin oxide nanopowder, organic solvent, and suitable dispersants through attrition process. Various comminution parameters during the attrition step were studied to optimize the process for the stable dispersion of indium tin oxide sol. The transparent and conductive films were fabricated on glass substrate using the indium tin oxide sol by spin coating process. To obtain antireflective function, partially hydrolyzed alkyl silicate was deposited as over-coat layer on the pre-fabricated indium tin oxide film by spin coating technique. This double-layered structure of the nanostructured film was characterized by measuring the surface resistance and reflectance spectrum in the visible wavelength region. The final film structure was enough to satisfy the TCO regulations for EMI shielding purposes.

Depending on the minimum size of their micro/nano structure, thin films can exhibit very different behaviors and optical properties. From optical waveguides down to artificial anisotropy, through diffractive optics and photonic crystals, the application changes when decreasing the minimum feature size. Rigorous electromagnetic theory can be used to model most of the components but when the size is of a few nanometers, quantum theory has also to be used. These materials including quantum structures are of particular interest for other applications, in particular for solar cells, because of their luminescent and electronic properties. We show that the properties of electrons in multiple quantum wells can be easily modeled with a formalism similar to that used for multilayer waveguides. The effects of different parameters, in particular coupling between wells and well thickness dispersion, on possible discrete energy levels or energy band of electrons and on electron wave functions is given. When such quantum confinement appears the spectral absorption and the extinction coefficient dispersion with wavelength is modified. The dispersion of the real part of the refractive index can then be deduced from the Kramers- Krönig relations. Associated with homogenization theory this approach gives a new model of refractive index for thin films including quantum dots. Absorption spectra of samples composed of ZnO quantum dots in PMMA layers are in preparation are given.

The Dyakonov-Tamm wave combines the features of the Dyakonov wave and the Tamm electronic state. Dyakonov-Tamm waves guided by the planar interface of two dissimilar chiral sculptured thin films (STFs) were systematically examined. The interfaces result from the chiral STFs being dissimilar in (a) orientation about the helical axis, (b) structural handedness, (c) structural period, (d) vapor incidence angle, (e) material, or (f) various combinations thereof. A boundary-value problem for the propagation of Dyakonov-Tamm waves was formulated and numerically solved. Up to three physical solutions were obtained for any specific combination of constitutive properties of the two chiral STFs. Each solution indicates the existence of a Dyakonov-Tamm wave. If more than one solutions exist, the corresponding Dyakonov-Tamm waves differ in phase speed and degree of localization to the interface.

The propagation of surface-plasmon-polariton (SPP) waves guided by a metallic defect layer in a sculptured nematic thin film (SNTF) was studied theoretically. The defect layer was taken to be deposited by electron-beam evaporation, and the SNTF was taken to be made by similarly evaporating titanium oxide. We found that when the defect layer's thickness is much greater than the penetration depth, SPP waves propagate guided by the two metal/SNTF interfaces independently. As the defect layer's thickness is reduced, coupling of the two interfaces results in new SPP waves. The smaller is the thickness of the metallic defect layer, the stronger is the coupling effect.

The low-frequency behavior of a set of wires with a very high conductivity is studied. The effective non-local constitutive relation is derived for wires with a finite height. Some numerical examples are described.

The macroscopic optical responses of sculptured thin films (STFs) can be engineered, and the composition and multiscale porosity of STFs can be exploited to promote preferential infiltration by certain chemical and biological species. Accordingly, STFs are attractive as platforms for optical sensing. We considered three aspects of the theory underpinning optical sensing of species which infiltrate STFs: (a) estimation of the constitutive and morphological parameters of infiltrated STFs by means of inverse homogenization; (b) the effect of infiltration on the reflectances and transmittances of infiltrated STFs; and (c) the effect of infiltration on the excitation of surface-plasmon-polariton waves guided by a planar metal/STF interface. Both columnar thin films and chiral STFs were considered. The sensitivity of the optical response of STFs to infiltration was found to bode well for their use in optical sensors.

Nanostructured porous silicon (nanoPS) particles with dual luminescent and magnetic properties have been fabricated and biofunctionalized aiming at cellular applications in both progenitor cell research and cellular therapy. The dual luminescent/magnetic nanoparticles (DLMNPs) have been fabricated by the electrodeposition of cobalt and iron into nanoPS. DLMNPs show luminescence properties as illustrated by photoluminescence measurements and direct fluorescence microscopy, and simultaneously exhibit magnetic properties. The resulting DLMNPs have been subsequently functionalized and internalized into cells. The experimental results show that luminescence remains several days and corroborate the biocompatibility of the DLMNPs. Such dual properties are relevant research tools as non toxic cellular tracker for progenitor cells and consequently able to be used in many strategies of cellular therapy. Additionally, the nanoPS-DLMNPs can be functionalized with various biomolecules that will provide them with new functionalities.

Silver is widely used for a fabrication of plasmonic devices due to its unique optical constants. Nanostructured Ag layer can exhibit strong localized surface plasmon resonance, which mainly affects its optical behavior in visible and near infrared spectra. The nanostructure of the Ag layer is mainly influenced during the initial stage of the silver nucleation. Therefore we focused our attention on the study of this stage of the silver growth. The nanostructured ultra-thin silver layers were prepared by means of the magnetron sputtering. The nucleation mode and the resulting nanostructure was controlled by the deposition conditions. The initial stage of the nucleation and the layer growth was studied by means of an optical monitoring, which is based on a principle of spectrophotometric measurement of sample reflectivity. The measured data were fitted to a model of layered structure. The non-continual (Volmer-Weber) mode of the layer nucleation was clearly distinguished in the monitored data. Thus we were able to estimate the point of the non-continual layer coalescence as well as the subsequent evolution of the surface roughness. The prepared nanostructured Ag layers were analyzed by Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM). Optical properties were studied by spectroscopic ellipsometry and spectrophotometry.

In this work, we are demonstrating resonant light transmission through hybrid multi-layered plasmonic crystals, which are formed by a coupled nanohole and a nanoparticle array. This structures are shown to provide the conventional extraordinary optical transmission (EOT) peaks and also a newly found cavity-based mode is introduced with an emphasis to its high sensing capabilities. Plasmon hybridization in coaxial nanocavities is also addressed, where the nanohole array and the nanoparticle array are in the same layer.

Ultrathin nanostructured metal films exhibit unusual properties and performances. Film functional properties depend strongly on the nanostructure that can be manipulated by varying nucleation and growth conditions. Hence, in order to control the nanostructure of aluminium thin film fabricated by RF magnetron sputtering, we focus on in-situ monitoring of electrical and optical properties of the growing layer as well as plasma characterization by mass and optical emission spectroscopy. The electrical conductivity and I-V characteristics were measured. The optical constants were obtained from optical monitoring based on a spectral ellipsometry. The relevant models (based on one or two Lorentz oscillators and B-spline function) are suggested to evaluate the data obtained from the monitoring techniques. The results of the in-situ monitoring are correlated with SEM analyses. We demonstrate the monitoring can distinguish the growth mode in the real-time. We can estimate the percolation threshold of the growing layer and control layer nanostructure. We show that the nanostructure can be manipulated by RF power variation. Optical functions exhibiting plasmonic behaviour in the UV range and a strong nonlinear course of I-V curves were obtained for ultrathin Al film deposited at lower growth rate.

We present a study on erbium-doped silicon rich silicon oxide (SRSO:Er) thin films grown by the magnetron cosputtering of a three confocal cathodes according to the deposition temperature and the annealing treatment. It is shown that several parameters such as the stoichiometry SiOx, the Erbium content and the fraction of agglomerated Silicon are strongly influenced by the deposition temperature. Especially, an increase of the fraction of agglomerated-Si concomitant to a reduction of the erbium content is observed when the deposition temperature is raised. These structural differences have some repercussions on the optical properties that lead to better performances for high-temperature deposited material. It is illustrated by the Er-PL efficiency that is higher for 500°C-deposited than for RT-deposited sample at all annealing temperatures. Finally an investigation of the different emitting centres within the films is performed with a cathodoluminescence technique to highlight the emission of optically-active defect centers in the matrix. It is shown that some oxygen vacancies, namely Silicon-Oxygen Deficient Centers, have a strong contribution around 450-500 nm and are suspected to contribute to the energy transfer towards Er3+ ions.

Zinc Oxide thin films of thickness 0.7μm has been prepared by spray pyrolysis technique on to the sapphire and glass substrates kept at 500°C. The films were formed using two different molar concentration ie 0.15 and 0.2M. These films were characterized for SEM and XRD analysis and it was observed that the average size of the crystallites were of order of 400nm and 325nm for sapphire and glass respectively. XRD analysis revealed that the intensity of peaks were more pronounced in sapphire as compared to glass. Moreover the intensity of (002) plane were increased in both the samples ( films on sapphire and glass) as the concentration of spray solution was increased. V-I characteristics were analyzed for both the samples (using two probe method) and was observed that resistivity for glass and sapphire were of order of 140ohm-cm and 110ohm -cm respectively. Moreover the films were annealed at temperature 350°C for 2hours in vacuum ( 10^-5 torr) and was found that resistivity for films on sapphire were decreased by 10¹. Optical properties for both the samples were studied and was found that band gap for films grown on sapphire was more by 0.02eV as compared to the films on glass.

In this work, nanosecond-pulsed from ultra-violet to infrared lasers: KrF (248 nm, 25 ns) and Nd:YAG (1064 nm, 532 nm, 355 nm, 5 ns) were employed for ablation and deposition of germanium films in background pressure of <10^-6 Torr. Deposition was carried out at room temperature on Si, GaAs, sapphire and glass. The as-deposited films, characterized by using scanning electron microscopy (SEM) and atomic force microscopy (AFM), consist of nano to micron-sized droplets on nanostructured film. The dependence of film properties on laser wavelengths and fluence are discussed.

Effects of O₂, N₂, Ar and He on the formation of micro- and nanostructured indium tin oxide (ITO) thin films were investigated in pulsed Nd:YAG laser deposition on glass substrate. For O₂ and Ar, ITO resistivity of ≤ 4 × 10^-4 Ωcm and optical transmittance of > 90% were obtained with substrate temperature of 250 °C. For N₂ and He, low ITO resisitivity could be obtained but with poor optical transmittance. SEM images show nano-structured ITO thin films for all gases, where dense, larger and highly oriented, microcrystalline structures were obtained for deposition in O₂ and He, as revealed from the XRD lines. EDX results indicated the inclusion of Ar and N₂ at the expense of reduced tin (Sn) content. When the ITO films were applied for fabrication of organic light emitting devices (OLED), only those deposited in Ar and O₂ produced comparable performance to single-layer OLED fabricated on the commercial ITO.