This is a copy of the slides presented at the meeting but not formally written up for the volume.

Conductive metal patterns can be fabricated through the selective electroless growth of silver on isolated nanocolloidal gold particles, deposited onto chemically functionalized substrates using microcontact printing. The transition from isolated nanoparticles to continuous, conducting silver films is characterised by a percolation threshold. Using spectroscopic ellipsometry in the visible and near-infrared spectral range on homogeneous particulate films, we have investigated this percolation threshold. From the ellipsometry spectra obtained as a function of electroless silver deposition times, the effective thickness as well as the complex dielectric function of the growing films are determined. For short deposition times, the optical spectra exhibit features characteristic of an effectively insulating, particulate layer. A maximum is observed in the imaginary part of the dielectric function, which shifts towards lower energy with increasing amounts of deposited silver. For thicker films, the appearance of a Drude-like free electron contribution to the optical spectra is exhibited by a strong increase of both the real and imaginary parts of the dielectric function towards lower energy. From the optical spectra, the percolation threshold is identified. The ellipsometry results are discussed in relation to DC conductivity measurements, which also reveal a percolation threshold. Furthermore, our conclusions and the advantages of our approach are discussed in relation to recently published in situ experiments, in which the growth of magnetron sputtered silver nanoparticles is monitored real-time yielding similar optical responses.

This is a copy of the slides presented at the meeting but not formally written up for the volume.

We have developed unique combinations of in situ and ex situ analytical techniques capable of providing information about thin film growth and interface processes at the atomic scale. The in situ techniques include time-of-flight ion scattering (TOF-ISARS) and mass spectroscopy of recoil ions (MSRI), functional in relatively high background pressure environments such as growth of oxide films in oxygen atmospheres. These techniques are not only powerful for understanding fundamental thin film science, but are also useful for establishing composition-microstructure-property relationships critical for the development of materials integration for fabrication of film-based micro and nanodevices. We will discuss examples of application to understanding ferroelectric and high-k dielectric film growth and interface processes and using this knowledge for developing integration of ferroelectric capacitors with silicon microcircuits for non-volatile ferroelectric random access memories (FERAMs), development of high-K dielectric capacitors for high-frequency devices, and development of new high-K dielectric layers for the next generation of nanoscale CMOS gates. This presentation will include a review of studies of a new TiAl layer developed in our laboratory that can be used as a material with a double diffusion barrier / bottom electrode functionality for integration of ferroelectric capacitors with CMOS devices for fabrication of FeRAMs, high-K dielectric layers with Cu electrodes for high frequency devices, and as a new high-K dielectric for the next generation of nanoscale CMOS devices. We will discuss results from systematic studies designed to understand TiAl film growth and oxidation processes using sputter-deposition in conjunction with complementary in situ characterization techniques mentioned above and ex situ transmission electron microscopy and electrical characterization. This work was supported by the US Department of Energy, BES-Materials Sciences, under Contract W-13-109-ENG-38.

This is a copy of the slides presented at the meeting but not formally written up for the volume.

Recent developments in strongly correlated materials, in particularly metal oxides, have led to many inventive ideas to apply these materials in novel device concepts. During the last decade a tremendous progress has been made in controlling these complicated materials. To name a few, these are the epitaxial growth technique, understanding of the properties of their defect structure, atomic-level control of their layering, in the case of oxides the manipulation of the oxygen contents and dopant densities, etc.. With our development of high-pressure reflection high-energy electron diffraction during pulsed laser deposition we are able to control the growth of these materials at atomic level. Two independent processes, i.e., nucleation and growth, play an important role during vapour-phase epitaxial growth on an atomically flat surface. Here, nucleation causes the formation of surface steps and subsequent growth causes the lateral movement of these steps. Both processes are determined by kinetics, since they take place far from thermodynamic equilibrium, and affect the final surface morphology. The applicability of high-pressure RHEED to extract the kinetic parameters, determining the growth of complex oxides in PLD, will be demonstrated. In PLD, deposition and growth are separated in time, which enables measurement of the kinetic parameters at growth conditions by monitoring the decay of the adatom density between the deposition pulses and the influence of the kinetics on the epitaxial growth of oxides will be presented.With this controlled growth one is able to design artificial materials with specific properties by atomic-scale tailoring of their compositions. In this presentation we will focus on the epitaxial growth of such heterostructures with special emphasis on growth kinetics as well as the termination control of each deposited layer (final and starting atomic configuration).

This is a copy of the slides presented at the meeting but not formally written up for the volume.

Description: Interfacial reactions in the Cu/Mg/Cu trilayer system during constant heat treatment have been in-situ studied by specular x-ray reflectivity (XRR). The evolution of interface interdiffusion/roughness and the nucleation and growth of CuMg2 phase have been analysed through the simultaneous refinement of selected parameters of several reflectivity scans measured during the heat treatment. Synchrotron radiation and an special experimental setup allowed scan times of 110s which covered a temperature range of 3.7 K when heating the sample at 2 K/min from room temperature to 603 K. By this method, significant differences in the behavior of both interfaces, Cu on Mg and Mg on Cu, have been observed during the nucleation and growth of the intermetallic phase, in complete accordance with previous calorimetric measurements.

This is a copy of the slides presented at the meeting but not formally written up for the volume.

We have developed an x-ray synchrotron based strategy for determining the element-specific atomic-scale structure of crystalline interfaces. When combined with XPS and AFM we gain chemical sensitivity and nano-scale morphology. Using conventional X-ray standing wave (XSW) analysis (based on single-crystal Bragg diffraction), the hkl Fourier component for a x-ray fluorescence-selected atomic species is measured. By summing together several such hkl Fourier components, it is possible to directly generate a 3D, direct-space, 0.5 Å resolution, image of the atomic distribution with respect to the bulk crystal primitive unit cell. We have recently demonstrated this for the cases of bulk impurity atoms [1], cations adsorbed at the aqueous / oxide interface [2], metallic atoms at semiconductor surfaces [3], and oxide supported catalysts [4]. This new model-independent XSW imaging approach proves to be very insightful for complex cases in which atoms occupy unknown multiple crystallographic sites. In comparison to direct-methods based on conventional diffraction, the Fourier inversion process for generating an XSW image is much simpler, since the hkl phase (as well as amplitude) of each Fourier component is directly measured. Based on these model-independent XSW atomic images, we then develop models to refine the data analysis into 0.05 Å resolved atomic lattice positions that are used to measure effects such as strain. As part of our procedure, we calibrate the XRF yields to achieve a quantitative measure of the occupation fraction (stoichiometry) as well as the occupation lattice site for each XRF detectable species. In separate XPS measurements, we correlate this structural information with the chemical state of the adsorbed species. We are now applying this method to ALD and MBE grown oxide/oxide, metal/oxide and oxide/semiconductor heteroepitaxial structures and observing how the atoms at the interface redistribute after oxidation and reduction processes. In combination with AFM we are also correlating the atomic-scale and nano-scale structure of metal nanocrystals grown on oxide surfaces. Future directions include microbeam in situ real-time studies of growth and ferroelectric polarity switching.[1] L. Cheng, P. Fenter, M. J. Bedzyk, N. C. Sturchio, Phys. Rev. Lett. 90, 255503-1 (2003).[2] Z. Zhang, P. Fenter, L. Cheng, N. C. Sturchio, M. J. Bedzyk, M. L. Machesky, D. J. Wesolowski, Surf. Sci. Lett., 554(2-3) L95 (2004).[3] A.A. Escuadro, D.M. Goodner, J.S. Okasinski, M.J. Bedzyk, Phys. Rev. B, 70 235416-1-7 (2004).[4]. C.-Y. Kim, J.W. Elam, M. J. Pellin, D.K. Goswami, S. T. Christensen, M. C. Hersam, P. C. Stair, M. J. Bedzyk, J. Phys Chem. B (in press) (2006).

This is a copy of the slides presented at the meeting but not formally written up for the volume.

The stress evolution during electrochemical deposition of metals on amorphous substrates was monitored by an in situ, real time cantilever curvature measurement technique. The technique used is similar to that employed for in situ stress measurements performed during physical vapor deposition of thin films, but has been modified for optimal use in an electrochemical system. The electrodeposited films displayed Volmer-Weber island growth behavior, and exhibited a compression-tension-compression stress development that could be correlated with discrete island formation, island-coalescence, and post-coalescence growth stages, respectively. Under constant current conditions, the voltage transient displayed a corresponding three-stage character. Atomic force microscopy images confirmed that the microstructures of the films underwent three-dimensional island nucleation and growth. In the post-coalescence regime, interruption of the deposition resulted in an exponentially decreasing stress relaxation. The overall stress behaviors during growth and after the growth interruption were found to be very similar to that observed during physical vapor deposition of films on amorphous substrates. The experimental results will be analyzed in terms of recently proposed stress generation mechanisms.

This is a copy of the slides presented at the meeting but not formally written up for the volume.

X-ray scattering and reflectivity have been effectively used to measure the atomic-scale structure of surfaces and interfaces for several decades. Modern synchrotron X-ray facilities now deliver sufficient flux to make time-resolved measurements on a wide variety of systems feasible. In particular, time-resolved X-ray structural studies of Pulsed Laser Deposition of SrTiO3 [1-4] have recently been shown to provide detailed insight into the atomic-scale growth mechanisms. In addition to determining the growth mode, the surface/interface roughness, and the film thickness, some of the dynamics of the energetic collisions and the details of the subsequent kinetic relaxation are experimentally accessible. Epitaxial films grown by PLD are now of high enough quality that standard descriptions in terms of continuous surface roughness are no longer adequate to describe the X-ray data accurately[5]. The time-resolved data sets provide both guidance for developing and mechanisms to test a new generation of multi-scale models.1. Fleet, A., D. Dale, Y. Suzuki, and J.D. Brock, Observed Effects of a Changing Step-Edge Density on Thin-Film Growth Dynamics. Physical Review Letters, 2005. 94: p. 036102.1-4.2. Fleet, A., D. Dale, A.R. Woll, Y. Suzuki, and J.D. Brock, Multiple Time Scales in Diffraction Measurements of Diffusive Surface Relaxation. Physical Review Letters, 2006. 96(5): p. 055508.1-4.3. Willmott, P.R., R. Herger, C.M. Schleputz, D. Martoccia, and B.D. Patterson, Energetic Surface Smoothing of Complex Metal-Oxide Thin Films. Physical Review Letters, 2006. 96(17): p. 176102.1-4.4. Tischler, J.Z., G. Eres, B.C. Larson, C.M. Rouleau, P. Zschack, and D.H. Lowndes, Nonequilibrium Interlayer Transport in Pulsed Laser Deposition. Physical Review Letters, 2006. 96(22): p. 226104.1-4.5. Dale, D., A. Fleet, J.D. Brock, and Y. Suzuki, X-ray scattering from real surfaces: discrete and continuous components of roughness. Submitted to Physical Review B, 2006.

This is a copy of the slides presented at the meeting but not formally written up for the volume.

Film growth in pulsed laser deposition (PLD) occurs from the energetic plume of material ejected from a solid target by pulsed laser ablation. The plume consists of a complex mixture of neutral and ionized atoms, molecules, and even small clusters with kinetic energies ranging from thermal to a few hundred eV. The extra kinetic energy provides a transient (nonequilibrium) enhancement of surface mobility and is believed to alter the nucleation and growth of thin films. However, the mechanisms by which the transient mobility enhancement affect the growth kinetics are not well understood. We use time-resolved surface x-ray diffraction (SXRD) measurements with microsecond range resolution to study the role of nonequilibrium processes in PLD of SrTiO3. The use of x-ray diffraction greatly simplifies growth kinetics studies because in the kinematic limit the x-ray intensity changes correspond directly to coverage changes. Rather than using a transport model to fit the data, we instead analyze the intensity transients using an approach that allows direct determination of the transient surface coverages from the diffraction intensities [1]. The initial change in the coverage shows the fraction of the pulse instantaneously forming on each layer, and the time evolution of the coverages shows the amount of material transferred from the top of the islands into the growing layer. This analysis reveals that the energy-enhanced interlayer transport occurs on a time scale of microseconds or less and it dominates layer filling in PLD growth. A much smaller fraction of material, which is governed by the dwell time between successive laser shots is transferred by slow, thermally driven interlayer transport processes. [1] J.Z. Tischler, Gyula Eres, B.C. Larson, C.M. Rouleau, P. Zschack, and D.H. Lowndes, Phys. Rev. Lett. 96, 226104 (2006).

This is a copy of the slides presented at the meeting but not formally written up for the volume.

Complex oxides exhibit various physical properties such as ferromagnetism, dielectricity, and superconductivity. The nature of these physical properties is determined by very small characteristic length scales. Future heteroepitaxial devices based on such oxides have great potential for applications provided that the growth can be controlled on an atomic level.Currently, in-situ growth morphology characterization is mostly performed by diffraction techniques such as Reflection High Energy Electron Diffraction (RHEED). We have now realized a system, in which Atomic Force Microscopy (AFM) can be performed during Pulsed Laser Deposition (PLD). Deposition and force microscopy are performed in one vacuum chamber and via a fast transfer (in the order of seconds) the surface of a sample can be scanned. In our system we take advantage of the pulsed deposition process, because microscopy measurements can be carried out between the pulses. This provides real-time morphology information on the microscopic scale during growth. The transfer mechanism allows switching between microscopy and deposition with a re-position accuracy of ±500 nm which gives new opportunities to study growth processes. This system is especially useful to study crystal growth, phase transitions, diffusion processes and nanoparticle formation. Furthermore, it will provide information if RHEED is not possible, for example during amorphous and polycrystalline growth. In this contribution, we will present the results obtained with a few model systems on oxide surfaces. We have used treated SrTiO3 (001) oxide substrates with 0.4 nm high substrate steps which are ideal for these experiments. Several materials are currently investigated, such as Au, SrRuO3, PbTiO3 and transparent conducting indium tin oxide. The in-situ AFM has been used to study the initial growth of these materials at various deposition conditions. The physical properties of these materials are correlated with the growth conditions, such as deposition pressure, fluency and substrate temperature. Besides showing the growth results obtained with the AFM, the latest equipment developments will be presented. To scan at elevated temperatures, small heaters have been developed. These small thermal mass heaters are designed in such a way to obtain stable monitoring settings at temperatures >973K in a high pressure environment or even ambient pressure. With high temperature microscopy, growth characterization at typical deposition conditions of complex oxides becomes feasible.