A rapid prototyping method for the fabrication of microstructures in polymer substrates has been developed, using a combination of laser direct-write patterning of silicon membrane contact masks and vacuum-ultraviolet (VUV) pulsed laser ablation. The process allows the flexible and rapid prototyping of microreactors and microchannel systems with submicrometer resolution. Thanks to the high photon energy of the VUV (7.9 eV) irradiation, PMMA and also other polymers can be ablated without leaving behind carbonated and/or fluorescent surfaces. Fluences of ≅ 100 mJ/cm2 lead to etch rates of ≅ 140 nm/pulse and result in very smooth surfaces with a roughness in the nanometer range on a micrometer lateral scale. The structured substrates are sealed with a PMMA foil by means of a newly developed low temperature technique without adhesives.

Closed-loop control and real-time monitoring of pulsed excimer laser cleaning and ablation have been realised by software and hardware design and development. The audible acoustic wave generated during excimer laser surface cleaning and ablation has been used as the feedback signal for the automatic control system of laser-surface interaction. Man–machine interface for laser operation and acoustic monitoring has been developed with LabVIEW 4.1 under Windows 95 environment. This system has been used to control and monitor laser cleaning and ablation processes in real-time and proven to successfully meet the requirements in our study. By database exchange, this automatic control system can also be applied to control drilling and materials removing.

Laser drilling has been carried out with a pulsed Nd:YAG laser. The laser has been applied to the drilling of APC-2 (PEEK-61%C fibre), with specimens up to 1 mm in thickness and using both moving and stationary beams. Hole shapes and heat-affected zone (HAZ) microstructures were studied using SEM, optical microscopy of polished sections and optical interferometric surface profilometry. Two prominent microstructural features were noted in the HAZ of the composite. These were (a) swelling of the ends of the carbon fibres (from about 8 microns to about 12 microns in diameter) and (b) an extensive zone around the hole in which the matrix had clearly undergone melting and some flow. The fibre swelling was such that neighbouring fibres were brought into close contact. The degree of swelling was found to remain constant as the laser pulse energy was increased, although the morphology of the fibre ends became more wrinkled and porous. The phenomenon is thought to be caused by internal gas pressure generation and distortion of the turbostratic structure within the fibre.

A heat flow model has been developed to simulate the drilling process, based on an explicit finite difference formulation and a Cartesian (3-D) mesh. The post-iterative heat accumulation method was used to simulate the effect of latent heat absorption. The explicit approach was found superior to implicit schemes, which tend to exhibit poor stability when handling the phase change algorithm in regions of extremely high thermal gradient. The total solution time was kept within reasonable limits by using a graded mesh, which was fine only in the regions close to the beam axis. Comparisons between predicted and observed hole dimensions showed good agreement over a range of conditions, including variations in beam energy and beam motion. This suggests that effects omitted from the model, such as melt ejection, were not playing a significant role.

Single phase, (100) oriented Ba0.5Sr0.5TiO3 (BST) thin films have been deposited onto (100) LaAlO3, SrTiO3, and MgO substrates using pulsed laser deposition (PLD). Interdigitated capacitors patterned on top of the ferroelectric film have been used to measure the dielectric constant and dissipation factor of these films as a function of DC bias and temperature at 1 MHz and as a function of DC bias and frequency (1 to 20 GHz) at room temperature. At room temperature, the capacitance can be reduced by as much as a factor of 4 using an electric field of ≤ 80 kV/cm. The dielectric properties (% tuning and dielectric loss) of the ferroelectric film is sensitive to both the deposition and post processing conditions. Optical imaging of the ferroelectric films using confocal scanning optical microscopy (CSOM) shows reproducible polarization fluctuations over sub-micrometer length scales. Dielectric loss in the ferroelectric film is reduced through a combination of post deposition processing and donor/acceptor doping of the films. A zero field tan5 = 0.01 - 0.005 has been measured for BST films which show significant tuning at microwave frequencies.

KrF excimer laser radiation (λ=248 nm, τ=25 ns) is used for pulsed laser deposition of BaTiO3 thin films on Pt/Ti/Si multilayer substrates. The processing gas atmosphere consists of O2 at typical pressures of p=10-3-5·10-1 mbar. The investigations concentrate on the influence of the substrate temperature and the kinetic energy of the film forming particles on the crystalline structure and orientation of the growing films.

X-ray diffraction measurements and polarization dependent micro Raman spectroscopy reveal oriented growth of the films with c-axis orientation normal to the substrate surface and [100] texture if the energy of the particles is > 60 eV, while at lower kinetic energies a [110] or [111] texture with partly a-axis orientation is preferred. The ferroelectricity and the dielectric constant of the films, as determined by polarization versus voltage (P-V) and capacitance versus voltage (C-V) impedance measurements, decreases with increasing kinetic energy of the film forming particles. This decrease of the dielectric properties correlates with the change of the preferred orientation and the crystalline quality of the films.

Ba1-xSrxTiO3 thin films have been deposited on Pt/Ti/SiO2/Si substra by the pulsed ArF laser deposition method. Deposition conditions, such as ambient gas and substrt temperatze, have been optmized to rrxove crystallinepropesty. Fe oelectric p e phasehasbeenobtainod ithe BSTthin filns deposited above 500°C in Q2 gas havingpressure ofabout 13Pa. Using N2O gas instead of O2 gas improved the crystallinity, because highly chemical active oxygen radicals produced due to ultraviolet inadiation of the laser. Doping of Bi ranging around 2% fills of the role of decrease leakage current of BST thin films. Temperature dependence of the dielectric constant (εr) shows a sharp change, peaking aroumd room temperature. The peak point exists below 25°C in the ratio of Ba/Sr=1.1 film, and shills above 50°C in Ba/Sr=5.7 film. When the Ba/Sr ratio is 1.4 the dielectric peak exists near 27°C and is very sharp. The maxinium differentW rate of dielectric constanttversus temperature is the largest in Ba/Sr=1.4 film and is about 100K-1. This value is equivalent to apyroelectric coefficient of 1.8 × 10-7 C/cm2K, which is almost the same as that of LiTaO3 single crystl, a typical pyroelectric material.

We have fabricated epitaxial PbZr0.52Ti0.48O3 (PZT, 40~1200 nm)/YBa2Cu3O7-x (YBCO, 400 nm) film ferroelectric/superconductor heterostructures on the single-crystal neodymium doped yttrium monoaluminate [YAlO3+1%Nd2O3] and MgO substrates by KrF pulsed laser deposition technique. The dielectric constant of 950 and loss tangent δ of 0.04 have been found to be frequency independent in the range 100 Hz to 100 kHz while electric resistivity ρ (150 kV/cm) is of 6×1011 Ω·cm, remnant polarization and coercive field are 32 μC/cm2 and 43 kV/cm, respectively. Fast ferroelectric switching kinetics with characteristic switching time around 50 ns has been observed. Universal electric field and temperature dependencies of switching time as well as film thickness dependence of coercive electric field have been observed and correspond to ferroelectric needle-like domain switching.

The perovskite oxide YBa2Cu3O7-x (YBCO) and Pb(ZrxTi1-x)O3 (PZT) thin films have been deposited for superconducting-ferroelectric devices. KrF excimer laser ablation technique was used at the deposition conditions of 200-600mTorr O2, 2-3J/cm2 and 5-10 Hz operation frequency. Heterostructures of PZT-YBCO-YAlO3:Nd show the zero resistivity critical temperature of 82K and excellent ferroelectric properties of remnant polarization 32 μC/cm2, coercive force of 80kV/cm and dielectric constant 800. Cycling fatigue characteristics and leakage current are also discussed.

We have fabricated a new ferroelectric memory FET, which consists of the Au/Pb(Zr0.52Ti0.48)O3/SiO2/Si gate structure. Ferroelectric PZT thin film with a thickness of 250~400 nm was prepared by using Excimer Laser Ablation Deposition. Silicon oxide successfully served as a buffer layer between ferroelectric and Si substrate to suppress the charge injection and prevent Pb interdiffusion. Electrical properties of the ferroelectric FET have been characterized through both the Capacitance vs. Voltage(C-V) and Current vs. Voltage(I-V) measurements, showing a typical memory characteristics of FET devices, i.e., the ON state and OFF state were nonvolatile for about thirty minutes and several hours, respectively.

Oriented, single phase thin films (~5000Å thick) of BaxSr1-xTiO3 (BST) have been deposited on to (100) MgO and LaAlO3 (LAO) single crystal substrates using pulsed laser deposition (PLD). A strong correlation is observed between the microstructure of the deposited film and the dielectric tuning and loss at microwave frequencies. Microstructural defects observed in as deposited films include strain, due to film substrate lattice mismatch and oxygen and cation vacancies. Compensation of the ablation target with excess Ba and Sr is observed to increase the dielectric constant and to reduce the dielectric loss. Post-deposition, bomb annealing of films at high temperatures (1250°C) is observed to fill oxygen vacancies and increase grain size. The difference in the dielectric behavior for as-deposited and low temperature annealed BST films on MgO and BST films on LAO is observed and may be attributed to the differences in film stress. A further improvement in the dielectric behavior is observed by the addition of donor/acceptor dopants such as Mn. The data shows that ferroelectric thin films can be used to build tunable microwave circuits that offer significant performance advantages over devices made from conventional semiconducting materials.

Pb(ZrxTi1-x)O3 (lead zirconate titanate or PZT) ferroelectric thin film capacitors are of considerable interest for the realization of memory devices such as nonvolatile random access memories (NVRAMs). The PZT capacitors were prepared on platinized silicon Pt/(100)Si using conducting oxide LaxSr1-xCoO3 (lanthanum strontium cobalt oxide or LSCO) as electrodes. The PZT and LSCO thin films were deposited by the KrF excimer laser ablation technique. The optimum preparation conditions such as oxygen pressure, laser energy influence and substrate temperature were investigated. The PZT and LSCO films grown on Pt/(100)Si are polycrystalline. The crystallographic properties of the films were determined using X-ray diffractometer (XRD) method. The electrical characterizations of the films including hysteresis loop, fatigue, and retention properties were determined by the RT66A Standardized Ferroelectric Test System.

La1-xCaxMnO3-δ (LCMO) thin films are grown by pulsed laser deposition on a (100) SrTiO3 substrate at temperatures between 530°C and 890°C. The magnetotransport properties show a high negative magnetoresistance and a shift of the maximum of the R(T) curve as function of temperature. The Curie temperature changes with deposition temperature and film quality in the range of 100-220K. The film quality is characterised by X-ray diffraction and transmission electron microscopy (TEM); film and target compositions were verified by atomic emission spectroscopy. The local structure of the film depends on the growth conditions and substrate temperature. TEM reveals a slight distortion of the film leading to a breakdown of the symmetry from orthorhombic to monoclinic. At the highest growth temperatures, a well defined interface is observed within the LCMO film, parallel to the substrate surface; this interface divides the film into two lamellae with a different microstructure. The lamella close to the substrate is perfectly coherent with the substrate, suggesting that it is strained as a result of the lattice parameter mismatch; the upper lamella shows a typical domain structure with unusual translation interfaces characterised by a displacement vector of the type 1/2 [010]m and 1/2[001]m when referred to the monoclinic lattice.

Barium ferrite films with high coercivity (>2000 Oe) have been prepared on single crystal sapphire substrates by laser in-situ deposition. The structures of these films were characterized by x-ray diffractometry. X-ray diffraction pattern shows a preferential c-axis orientation normal to the film plane at a high deposition temperature and a random orientation at a lower deposition temperature. The magnetic properties of the films were analysed by a Vibrating Sample Magnetometer (VSM) and surface morphology was analysed by an Atomic Force Microscope (AFM).

Submicron thick Bi, Ga substituted dysprosium iron garnet films were laser deposited on Gd3Ga5O12(GGG) and ceramic glass substrates at room temperature and then post annealed by rapid thermal annealing (RTA). From Faraday rotation studies, the films deposited on glass substrates are found to exhibit perpendicular magnetic anisotropy, Faraday rotation of 0.88 deg / μm, and coercive field Hc of 0.88 kOe. On the other hand, films deposited on GGG substrates with the same processing parameters are found to exhibit perpendicular anisotropy, but with much smaller values for Faraday rotation(0.03 deg; μm) and coercive field Hc(0.018 kOe). The uniaxial magnetic anisotropy with easy magnetization axis perpendicular to the film surface is caused by the stress induced on the polycrystalline film / substrate interface. The effect of changing the oxygen pressures, in the range of 20 to 100 mTorr during the deposition process, on the crystalline structure as well as coercive field and Faraday rotation angle are also presented.

Controlled microstructured thin films with nominal composition Cu95Co5 have been deposited on glass substrates by pulsed laser ablation at room temperature, in vacuum, for different target speed rotation. Atomic Force Microscopy, AFM, studies have shown a surface roughness not higher than 0.5 nm, for the as-deposited samples, which do not exhibit magnetoresistive, MR, behaviour. X-ray diffraction analysis show broad diffraction peaks, slightly shifted from pure Cu reflection peaks. After annealing, the samples show GMR. The AFM investigations reveal a surface roughness of =6.8 nm and =9.2 nm for the samples prepared with high and low target speed rotation, respectively. Furthermore the GMR data correspond to a strong anisotropic behaviour. A reversible MR is exhibited, for all the films, exclusively for perpendicular to the films plane applied magnetic field. Hysteretic MR behaviour is observed for any other direction: in the range of 70-80 deg., coercive MR fields from 0.17 Tesla to 0.05 Tesla are observed for the samples obtained at 10 rpm to 32 rpm respectively target speed rotation. These properties are discussed in terms of the shape anisotropy of magnetic Co nanoparticles.

Two models, based on hydrodynamic and Direct Simulation Monte Carlo approaches, have been investigated for the simulation of species fluxes arriving at substrates during pulsed laser deposition of thin films. The models are assessed in light of the results of mass spectrometric and optical imaging observations of the plume. Model predictions of film composition are compared with the results of microscopic compositional analysis across a deposited BaTiO3 film. The spatial distributions of the relative abundance of total Ba and Ti were a particular focus of this study, with the latter model giving the best agreement with experiment. The Monte Carlo simulation results indicate that the incoming concentration ratio of total Ba to Ti, across the substrate surface, is strongly modified by gas collisions within a compressed region that forms between the infalling plume and the substrate surface, and also by momentum exchange (scattering) between the lighter plume species and the added background gas.

Epitaxial YBa2Cu3O7-δ (YBCO) films were fabricated using laser ablation of YBCO onto rolling-assisted-biaxially-textured-substrates (RABiTS) at a temperature of 650°C. The configuration of the sample was YBCO/YSZ/CeO/Ni. The CeO2 and YSZ buffer layers were deposited using electron-beam evaporation and sputtering, respectively. Both of these techniques are considered to be industrially scalable. SEM images of the YBCO reveal a range of structures ranging from jumbled a-axis to dense c-axis morphologies depending upon the deposition conditions. X-ray θ-2θ scans show a similar c-axis dependence on the deposition conditions.

Biaxially oriented yttria stabilized zirconia (YSZ) and Pr6O11 buffer layers were grown at room temperature by Ion-Beam Assisted Laser Deposition (IBALD) on metal substrates. Dependent on deposition parameters, IBALD grown films showed in-plane orientations of about 10° FWHM (full-width at half maximum) for both systems. In contrast to the YSZ system, where best in plane alignment is found for a [111] direction oriented parallel to the ion beam, the Pr6O11 system shows best in-plane alignment at nearly gracing incidence of the ion beam. An additional thin intermediate CeO2 layer improves the heteroepitaxial growth of YBCO on highly biaxially oriented YSZ films. Pulsed Laser Deposition (PLD) was also used to grow epitaxial CeO2 buffer layers directly on biaxially textured Ni-tapes. SIMS investigations showed an interdiffusion zone of about 0.5μm at standard deposition conditions, but no enhanced grain boundary diffusion could be observed.

Pulsed-laser ablation was used to deposit YBa2Cu3O7-x (YBCO) films on LaAlO3 and metallic substrates in an effort to understand and develop the processing of coated conductors with enhanced properties. Doping of YBCO films with Nd was utilized as an approach for increasing their flux pinning properties. Separate targets of Nd2O3 and YBCO were used instead of a pre-mixed Nd2O3-YBCO target. The critical current density (Jc) of the films was measured by whole body dc transport measurements and the transition temperature (Tc) by ac susceptibility. The composition vs. depth profiles of the films were obtained by Secondary Ion Mass Spectrometry. The critical current of a 5000 Å thick Nd-doped YBCO film on a LaAlO3 substrate was measured at 77 K and found to be 57 A (Jc = 1.1×106 A/cm2).

In this paper we report our investigations related to the growth and characterization of superconducting stacked structures of YBaCuO(undoped)/YBaCuO(Ag-doped)/YSZ layers processed on Si(100) substrates. These films were deposited using pulsed laser deposition (PLD), and have been characterized using X-ray diffraction, scanning electron microscopy (SEM), and four probe electrical measurements. SIMS analysis has also been used to study the incorporation and diffusion of carbon in the superconducting layer. The focus of this work is on the issues of the role of silver in the superconductor, and its effects on the transport properties and microstructure of the structure. We also discuss the use of these films for bolometer device applications.