The reduction in cathodoluminescent (CL) degradation of ZnS:Ag phosphor particles coated with aluminum doped zinc oxide (ZAO) films has been investigated. The films were deposited under various oxygen pressures using the atomic flux coating process. The characteristics of the coated phosphor particles with respect to as-received ones were investigated by x-ray photoelectron spectroscopy, CL degradation and scanning electron microscopy. All coated phosphor particles exhibited less CL degradation than the uncoated particles. The coatings deposited under 1.6×10-4 Torr of oxygen, a pressure much lower than the optimum one required to obtain highly transparent and conductive ZnO:Al films, provided the longest brightness lifetime. This increased phosphors lifetime was attributed to the high reactivity of the oxygen deficient ZAO coatings which acted as a sacrificial layer and trapped reactive species before they can reach the phosphor particles and alter their chemical composition.

We describe an oblique incidence optical transmittance difference technique for determining the pointing stability of a laser. In this technique, we follow the angular drift a monochromatic laser beam by measuring the relative changes in transmittance through a parallel fused quartz window for s- and p- polarized components of the beam in response to the drift. This method is shown in the present experiment to have the sensitivity to detect angular changes in the range of 1.7 νradians. To demonstrate the technique we measured the angular drifts of two commercially available lasers.

Pulsed Laser Deposition method (PLD) was used to grow nitinol (NiTi) thin films with goal of investigating their biocompatibility. High purity Ni and Ti targets were alternatively ablated in vacuum with a laser beam (λ=355 nm, 10 Hz) and the material was collected on room temperature Ti substrates. X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy and atomic force microscopy analyses have been performed to investigate the chemical composition, crystalline structure and surface morphology of the NiTi films. The nitinol layers biocompatibility has been tested using as a metric the extent to which the cells adhere during the culture period on the surface of NiTi layers deposited on Ti substrates. Vero and fibroblast cell lines dispersed into MEM (Eagle) solution containing 8% fetal bovine serum, at 37° C, were used for tests. Preliminary studies indicate that the interaction at the interface is specifically controlled by the surface morphology, (especially by surface roughness), and by the chemical state of the surface. Cell behavior after contact with NiTi/Ti structure for different intervals (18, 22 and 25 days for the Vero cells, and after 10 and 25 days for fibroblasts) supports the conclusion that NiTi is a very good candidate as a biocompatible material.

Hf metal thin films were deposited on Si substrates using a pulsed laser deposition technique in vacuum and in ammonia ambients. The films were then oxidized at 400 °C in 300 Torr of O2. Half the samples were oxidized in the presence of ultraviolet (UV) radiation from a Hg lamp array. X-ray photoelectron spectroscopy, atomic force microscopy, and grazing angle X-ray diffraction were used to compare the crystallinity, roughness, and composition of the films. It has been found that UV radiation causes roughening of the films and also promotes crystallization at lower temperatures.Furthermore, increased silicon oxidation at the interface was noted with the UVirradiated samples and was shown to be in the form of a mixed layer using angle-resolved X-ray photoelectron spectroscopy. Incorporation of nitrogen into the film reduces the oxidation of the silicon interface.

Photosensitive organic-inorganic hybrid polymers were synthesised for integrated optical and optoelectronic devices by a non-hydrous sol-gel process of hydrolysis/condensation of 3-methacryloxypropyltrimethoxysilane (MPS), diphenyldimethoxysilane (DPhDMS), and zirconium isopropoxide (TPZ) with boric acid under anhydrous conditions. The methacryl groups of MPS are UVpolymerizable, which are suitable for low cost fabrication of waveguides with a “UV write/develop” process. The incorporation of DPhDMS and TPZ was found useful in reducing the optical loss and in enhancing the thermostability of the polymer. The refractive index of the hybrid polymer is tuneable from 1.4950 to 1.5360 by variation of the ratio among MPS, DPhDMS and TPZ. Optical characterisation showed that the material has low optical losses at the telecommunications windows (0.16 dB/cm at 1310 nm and 0.4 dB/cm at 1550nm). The hybrid polymer also showed a low birefringence (1.2×10-4), a large thermo-optic (TO) coefficient (-2.77 ×10-4), and an outstanding linearity of dn/dT in a wide range of temperature (from 25 °C to 200 °C). Waveguides forming ability for the hybrid polymer with UV imprinting was also demonstrated.

High quality Sn-doped In2O3 (ITO) thin films have been grown by pulsed laser deposition (PLD) on glass, flexible polyethylene terephthalate (PET) and single crystal yttria stabilized zirconia (YSZ) substrates for use in organic light emitting diodes (OLEDs). Critical electrode issues for the OLED are related to the optical transparency, electrical resistivity, work function and surface roughness of the ITO film. Our research has focused on improving the properties of the ITO film to increase the efficiency of the OLED. Films were deposited using a KrF excimer laser (248nm, 30 ns FWHM) at fluences of 2 J/cm2 at substrate temperatures ranging from 1 to 100 mTorr. For ITO films (∼ 100 nm thick) deposited at the optimized conditions, a resistivity of 4.1 × 10-4 Ω-cm, 2.2 × 10-4 Ω-cm, 1.8 × 10-4 Ω-cm was observed on PET, glass and YSZ, respectively. The average film transmission in the visible range (400 - 700 nm) was about 90 % and the film surface roughness was about 0.5 nm for the film grown on glass. The Hall mobility and carrier density for ITO films (300 nm thickness) were observed to be in the range of 28 - 34 cm2/V-s and 1.0 - 1.2 × 1021 cm-3, respectively. We have used the ITO films, deposited by PLD on glass, plastic and single crystal YSZ substrates, as an anode contact in OLEDs. The OLED device performance based on PLD ITO anodes is compared with that of the device fabricated on the commercial ITO anode.

The femtosecond (fs) lasers display noticeable specificities compared with the nanosecond (ns) ones operating in the UV domain, and classically used for the pulsed-laser deposition (PLD) technique. The ultra-short laser pulses offer the feature of minimal thermal damage induced in the target material, and the very high intensities (1012-14 W/cm2) available with fs lasers are likely to allow the ablation of any kind of materials, even the wide band gap insulators.

The morphology, structure, composition and properties of the films obtained by fs PLD are studied according to the experimental growth conditions, the nature of the target material, and the dynamic expansion of plasma plume. In the case of ZnO, smooth, dense and nanocrystalline films (10 to 30 nm crystallites) can be epitaxially grown on adequate substrates (i.e. sapphire). On the contrary, BaTiO3 films are formed by the random stacking of aggregates (10 to 200 nm) leading to a non negligible surface roughness,. In addition, the chemical composition of fs PLD thin films of multicomponent compound (i.e. BaTiO3) is not homogeneous, an enrichment in the lighter element being observed in the central part of the film. These properties are related to the phenomena taking place during the various steps of the process (laser-matter interaction, plasma formation, expansion) through time resolved emission spectroscopy and plume optical imaging measurements.

Uniform Samarium oxide (Sm203) films were grown on 75-mm diameter silicon wafers by the pulsed laser deposition (PLD) technique. The beam of a KrF excimer laser was used to ablate an Sm2O3 target in an oxygen pressure of 30 mTorr. The crystal structure, surface morphology and optical properties of Sm2O3 films deposited at a temperature range of 25∼680°C were determined by XRD, FE-SEM, and spectra reflectance respectively. Monoclinic structure was the predominant phase for Sm2O3 films deposited at temperatures of 680°C and 400°C. Amorphous or partially crystallized amorphous phase was observed at deposition temperatures of 25°C and 200°C. The Sm2O3 film deposited at 680°C is very dense, while films deposited at lower temperatures have higher porosity. The values of index of refraction, n, and extinction coefficient, k, at λ = 633 nm are 1.867 and 0.0660, respectively, for the 680°C film, and are in a range of 1.5∼1.6 and 0.01∼0.04 respectively for films deposited at lower temperatures.

We have investigated atomistic processes of nucleation and crystallization in excimer-laser annealed thin Si films on glass based on molecular-dynamics (MD) simulations using the Tersoff potential. MD cells composed of up to approximately 50000 Si atoms were heated to produce melted Si, and then melted Si was quenched under various supercooled conditions with or without a temperature gradient and the corresponding nucleation processes were visualized. Lateral growth of thin Si crystalline films was also simulated by embedding a crystalline nano-particle with various crystal surfaces in melted Si. It has been found that the crystal surfaces become predominantly {111} during the lateral growth processes.

We studied adsorption, growth and desorption of Xe on Nb(110) using an in-situ obliqueincidence reflectivity difference (OI-RD) technique and low energy electron diffraction (LEED) from 32 K to 100 K. The results show that Xe grows a (111)-oriented film after a transition layer is formed on Nb(110). The transition layer consists of three layers. The first two layers are disordered with Xe-Xe separation significantly larger than the bulk value. The third monolayer forms a close packed (111) structure on top of the tensile-strained double layer and serves as a template for subsequent homoepitaxy. The adsorption of the first and the second layers are zeroth order with sticking coefficient close to one. Growth of the Xe(111) film on the transition layer proceeds in a step flow mode from 54K to 40K. At 40K, an incomplete layer-by-layer growth is observed while below 35K the growth proceeds in a multilayer mode.

Direct photo-imprinting of both surface relief pattern and refractive index modulation upon the organically modified germanosilicate (ORMOGSIL) glass using its large volume change was performed by ultraviolet exposure. A large refractive index increase up to 10-2 is induced by ultraviolet-induced densification in the ORMOGSIL glasses. The photosensitivity in the ORMOGSIL glass was enhanced by introducing a photo-polymerizable methcrylate group in the glass structure. Also, a surface AFM scans and optical microscope images of unetched sample show that the volume compaction in the ultraviolet illuminated region is associated with periodic pattern inscription.

The effect of the laser energy density used to deposit Bi onto amorphous aluminum oxide (a-Al2O3) on the growth of Bi nanocrystals has been investigated using transmission electron microscopy of cross section samples. The laser energy density on the Bi target was varied by one order of magnitude (0.4 to 5 J cm-2). Across the range of energy densities, in addition to the Bi nanocrystals nucleated on the a-Al2O3 surface, a dark and apparently continuous layer appears below the nanocrystals. Energy dispersive X-ray analysis on the layer have shown it is Bi rich. The separation from the Bi layer to the bottom of the nanocrystals on top is consistent with the implantation range of Bi species in a-Al2O3. As the laser energy density increases, the implantation range has been measured to increase. The early stages of the Bi growth have been analyzed in order to determine how the Bi implanted layer develops.

Hard surface coatings and thin layers can be synthesized by irradiating pure substrates with short laser pulses in reactive atmospheres. Various lasers with different pulse durations τ and wavelengths λ can be used for this purpose: XeCl excimer laser, Nd-YAG laser, free electron laser and Ti:sapphire laser. The irradiation of materials such as aluminum, iron and silicon in controlled nitrogen and methane atmospheres leads to surface modifications (e.g. hardness improvement) and to the formation of homogeneous coatings. The evolution of the surface properties (phase formation, hardness) as well as the mass transport mechanisms during the laser irradiation have been studied in detail as a function of the experimental parameters (laser fluence, ambient gas pressure, number of laser shots) for the Excimer Laser treatments. The formation of homogeneous AlN layers after irradiation of aluminum substrates in N2 atmosphere, the synthesis of homogeneous cementite coatings after irradiation of iron substrates in CH4 atmosphere and the successful incorporation of carbon after irradiation of (100) and (111) silicon single crystals in methane gas will be reported.

A comparative study of the effect of ultrashort (0.5 ps) and short (30 ns) pulses on Laser transfer of Cr is presented in this paper. The dynamics of the process was investigated by stroboscopic schlieren imaging for time delays up to 3 νsec following the laser irradiation pulse. In contrast to the ns laser the directionality of the ejected material is very high in the case of the sub-ps laser process. The narrow angular divergence (3°) of the sub-ps pulses permits the direct dynamic transfer of the material and opens up new application possibilities for the fabrication of high spatial resolution microstructures.

A simple strategy for generating and distributing metallic nanoparticles in polymer matrix with a spatial control in micrometer/nanometer scale has been proposed and successfully demonstrated by combination of two-photon photoreduction and femtosecond laser interference technique. The simultaneous spatially controlling generation and organization of metallic nanopartciles were controllable by designing interference patterns and varying laser intensity and exposure time. This strategy provides a simple and rapid approach for creating templates with designed spatial distribution of the nanoparticles, which is favorable for current microelectronics technology. This method also can be utilized in developing mass production processes for future nanodevices.

In As nanoparticles have been produced by picosecond pulsed laser ablation of bulk targets in the presence of an inert backing gas. Atomic force microscopy measurements show particles ranging in size from one to ten nm. Stoichiometry of the targets, determined by Rutherford backscattering measurements, are typically preserved within ten percent. Optical absorption and raman scattering data help confirm the crystalline, quantum confined nature of the nanoparticles.

Femtosecond (fs) laser application in three-dimensional (3D) optical recording is introduced. The laser irradiation on transparent glass and polymer matrix doped with fluorescent material is carried out, which changes the physical or chemical properties of the recording media and records information bits. With the change of the focusing positions inside the transparent substrates, 3D optical recording can be available for ultrahigh capacity data storage. Feasibility on fs laser drilling of poly-caprolactone (PCL) thin films for tissue engineering is investigated. It is found that precisely defined micro-hole arrays can be formed on the sample surfaces. Hydrophilic property of the processed samples is much improved, which provides good conditions for tissue cells to anchor on the man-made skin. Fs laser applications to form nanostructures on substrate surfaces are studied. Fs laser combination with near-field scanning optical microscopy (NSOM) to induce surface property modification in the sub 50-nm under NSOM tip and nanoparticles is also discussed.

A significant improvement in corrosion resistance of the protecting oxide of alloys has been observed when adding small amounts of reactive elements, such as yttrium, this effect has been called reactive element effect (REE). The general mechanism of the REE has not been determined yet. In this work, we study a growing of a yttrium oxide film and its interaction with the phases η and α that constitutes the alloy Zn-22Al-2Cu named ZinalcoTM The alloy's surface was coated by a pulsed laser deposition technique. The deposit is controlled and characterized by x-ray photoelectron spectroscopy. The mechanism by which the reactive element produce its effects in this alloy is explained by the preferential interaction among the active sites related to the zinc rich phase and enhancing aluminum movement toward the surface where it is oxidized and the protection film formed.

Strontium sulfide (SrS) is known to have an indirect bandgap of ∼ 4.32 eV. When doped with tellurium (Te), ultraviolet emission occurs at 360 nm (for Tes singlet) and 400nm (for Tes- Tes dimers) due to radiative recombination from bound exciton states. In this paper we discuss the ultraviolet emission of pulsed laser deposited thin films of SrS:Te grown as SrS-Te and SrSTe- SrS multi-layer structures on Si substrates. The Te doping was incorporated by conventional diffusion into the SrS films. Temperature dependent ultraviolet emission measurements were taken and will be discussed along with results from microstructural and chemical characterization techniques.

ZrC thin films were grown on Si substrates by the pulsed laser deposition (PLD) technique. X- ray photoelectron spectroscopy, x-ray diffraction and reflectivity, variable angle spectroscopic ellipsometry, and four point probe measurements were used to investigate the composition, density, thickness, surface morphology, optical and electrical properties of the grown structures. It has been found that crystalline films could be grown only by using fluences above 6 J/cm2 and substrate temperatures in excess of 500 °C. For a fluence of 10 J/cm2 and a substrate temperature of 700 °C, highly (100)-textured ZrC films exhibiting a cubic structure (a=0.469 nm) and a density of 6.7 g/cm3 were deposited. The use of a low-pressure atmosphere of C2H2 had a beneficial effect on crystallinity and stoichiometry of the films. All films contained high levels of oxygen contamination, especially in the surface region, because of the rather reactive nature of Zr atoms.