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A new ultrahigh-resolution photoemission electron microscope called PEEM3 is being developed and built at the Advanced Light Source (ALS). An electron mirror combined with a much-simplified magnetic dipole separator is to be used to provide simultaneous correction of spherical and chromatic aberrations. It is installed on an elliptically polarized undulator (EPU) beamline, and will be operated with very high spatial resolution and high flux to study the composition, structure, electric and magnetic properties of complex materials. The instrument has been designed and is described. The instrumental hardware is being deployed in 2 phases. The first phase is the deployment of a standard PEEM type microscope consisting of the standard linear array of electrostatic electron lenses. The second phase will be the installation of the aberration corrected upgrade to improve resolution and throughput. This paper describes progress as the instrument enters the commissioning part of the first phase.

Many environmental and health impacts from semiconductor processing are tied to the design of the manufacturing equipment. Evaluating solutions to properly treat effluents from semiconductor tools has become an increasingly important part of supply chain management and equipment procurement decisions. Accordingly, understanding the environmental footprint associated with equipment sets is essential for both equipment manufacturers and semiconductor manufacturers seeking to improve their products' environmental and financial performance. Equipment environmental performance must be evaluated within the context of the factory infrastructure and auxiliary equipment sets, with appropriate allocations of impacts from additional steps, both upstream and downstream of the wafer processing tools (chemical precursor delivery as well as byproducts treatment). Several challenges to environmental assessments arise from the nature of semiconductor manufacturing itself, due to short process life cycles, complexity of processes, and the need to track diverse inter-related impacts. Environmental value systems analysis (EnV-S) is an analytical tool to evaluate the environmental performance of semiconductor processing. EnV-5 develops environmental assessments through a "bottom-up" analysis approach, assembling equipment environmental models to describe a system. This paper presents the use of EnV-S as a tool to quantify the environmental impact of a product or process by creating an operational signature along multiple dimensions of cost and environmental and health factors. The use of EnV-S is illustrated through a case study comparing systems that abate emissions from dielectric chemical vapor deposition processes.

Crystal growth rates during laser-induced, liquid-mediated crystallization of amorphous Ge were measured with movie-mode dynamic transmission electron microscopy (MM-DTEM), a photoemission microscopy technique with nanosecond-scale time resolution. Films of 50-nm thick amorphous Ge were crystallized using a 12-ns laser pulse with a Gaussian spatial profile, which established high local temperature gradients in the specimen. Crystallization proceeded by the formation of a central zone with a high nucleation rate (zone I), followed by liquid-mediated outward growth of columnar grains (zone II), followed by spiraling growth (zone III) until the crystallization halted in cooler parts of the specimen. Zone II growth was imaged for several laser pulse energies with 20-ns electron pulses with 95 ns between frames. A thin liquid layer between the solid amorphous phase and the advancing crystallization front during zone II growth was imaged. The zone II growth rate for each experiment remained nearly constant although the crystallization front passes through a large temperature gradient. Measured growth rates ranged from 5.7 to 13.6 m/s, consistent with transient liquid layer mediated growth rather than solid-state growth. In contrast with a previous report, the growth rate did not increase systematically with laser energy or absorbed energy. The new results, together with previously reported data, suggest that both sets of experiments were conducted under conditions where the growth rate saturates near its maximum value. A phenomenological model based on the concept of upper and lower threshold temperatures for the zone II growth was fitted to the data from these experiments and previous MM-DTEM crystallization experiments. [ABSTRACT FROM AUTHOR]

Fluorine radicals are generated from NF3 or F2 in microwave-generated and low-frequency (LF)-generated plasmas and are passed through flow tubes under various flow, pressure and dilution conditions. The F relative concentration decreases from ~80 percent to ~20 percent, and the F2 relative concentration increases from ~20 percent to ~80 percent, as the pressure is varied over the range 0.5-10 Torr.

While the process of metal induced crystallization (MIC) is widely used in the fabrication of thin film electronic devices, its application to the field of thermoelectrics is fairly new. Especially, its implementation in the field of the classic thermoelectric material SiGe could lead to a low cost approach by combining the benefits of low thermal budget, self-doping, and thin film and sputter deposition compatibility. In this work, samples consisting of SiGe/Al multilayers deposited on aluminum oxide based substrates have been prepared. Special emphasis was put on the ratio of Al to SiGe and the resulting changes in transport properties during annealing. On one hand, a certain amount of Al is needed to ensure a complete MIC process for the SiGe, but on the other hand, an excess of Al results in a metallic system with low thermoelectric efficiency. In-situ characterization during annealing of the samples was carried out via x-ray diffraction, electrical resistivity, and Seebeck measurements. [ABSTRACT FROM AUTHOR]

Strong luminescence in visible and infrared spectral ranges, corresponding to intra-4f-shell transitions of Er3+ (4f11) ions, have been observed in Si(100) substrates which have an epitaxially grown Ca(1-x)ErxF(2 + X) thin film. Intra-4f-shell transitions are measured at room temperatures by using photoluminescence and cathodoluminescence. Ca(1-x)ErxF(2 + x)/Si(100) systems can be used in novel silicon-based optoelectronic devices operating in the visible and near-infrared regions.

The properties of Ca1-xErxF2+x solid solution layer grown on Si(100) substrates are studied. CaF2 and ErF3 powders are mixed at high temperature using a reactive oxide as catalyst to form the solutions. X-ray diffraction andRutherford backscattering measurements are then performed to characterize the solution. Results show that Ca1-xErxF2+x thin films with theoretical mole fraction of less than or equal to 0.2 can be obtained from sublimation under ultrahigh vaccum of high purity solid solution powders.

Rutherford backscattering spectroscopy of alpha particles wasused to analyze the composition of SrF2 thin films deposited on carbon plates. The results showed that at the temperature of 270 degrees centigrade, the thin films were observed to be stochiometric, homogenous and quasi-insensitive to exposure to the air. The channeling phenomenon illustrated the structure of these layers.

Ga-Sb alloys with compositions ranging between ∼12 and 50 at. % Ga are promising materials for phase change random access memory applications. The short-range structures of two such alloys with compositions Ga14Sb86 and Ga46Sb54 are investigated, in their amorphous and crystalline states, using 71Ga and 121Sb nuclear magnetic resonance spectroscopy and synchrotron x-ray diffraction. The Ga and Sb atoms are fourfold coordinated in the as-deposited amorphous Ga46Sb54 with nearly 40% of the constituent atoms being involved in Ga-Ga and Sb-Sb homopolar bonding. This necessitates extensive bond switching and elimination of homopolar bonds during crystallization. On the other hand, Ga and Sb atoms are all threefold coordinated in the as-deposited amorphous Ga14Sb86. Crystallization of this material involves phase separation of GaSb domains in Sb matrix and a concomitant increase in the Ga coordination number from 3 to 4. Results from crystallization kinetics experiments suggest that the melt-quenching results in the elimination of structural 'defects' such as the homopolar bonds and threefold coordinated Ga atoms in the amorphous phases of these alloys, thereby rendering them structurally more similar to the corresponding crystalline states compared to the as-deposited amorphous phases. [ABSTRACT FROM AUTHOR]

The structural, thermodynamic, and kinetic aspects of the transformations between the metastable amorphous and crystalline phases of GaSb are investigated as a function of pressure at ambient temperature using synchrotron x-ray diffraction experiments in a diamond anvil cell. The results are consistent with the hypothesis that the pressure induced crystallization of amorphous GaSb into the β-Sn crystal structure near ∼5 GPa is possibly a manifestation of an underlying polyamorphic phase transition between a semiconducting, low density and a metallic, high density amorphous (LDA and HDA, respectively) phases. In this scenario, the large differences in the thermal crystallization kinetics between amorphous GaSb deposited in thin film form by sputtering and that prepared by laser melt quenching may be related to the relative location of the glass transition temperature of the latter in the pressure-temperature (P-T) space with respect to the location of the critical point that terminate the LDA ↔ HDA transition. The amorphous → β-Sn phase transition is found to be hysteretically reversible as the β-Sn phase undergoes decompressive amorphization near ∼2 GPa due to the lattice instabilities that give rise to density fluctuations in the crystal upon decompression. [ABSTRACT FROM AUTHOR]

Chalcogenide-based phase-change materials have wide use in optical recording media and are growing in importance for use in non-volatile electronic memory. For both applications, rapid switching between the amorphous and crystalline phases is necessary, and understanding the changes during rapidly driven phase transitions is of scientific and technological significance. Laser-induced crystallization and amorphization occur rapidly and changes in atomic structure, microstructure, and temperature are difficult to observe experimentally and determine computationally. We have used nanosecond-scale time-resolved diffraction with intense electron pulses to study Ge2Sb2Te5 during laser crystallization. Using a unique and unconventional specimen geometry, cycling between the amorphous and crystalline phases was achieved, enabling in situ transmission electron microscope (TEM) study of both microstructural and crystallographic changes caused by repeated switching. Finite element analysis was used to simulate interactions of the laser with the nano-structured specimens and to model the rapidly changing specimen temperature. Such time-resolved experimental methods combined with simulation of experimentally inaccessible physical characteristics will be fundamental to advancing the understanding of rapidly driven phase transformations. [ABSTRACT FROM AUTHOR]

The chemical and structural effects of processing on the crystallization of nitrogen doped Ge2Sb2Te5 is examined via x-ray photoelectron spectroscopy (XPS), x-ray absorption spectroscopy (XAS), time resolved laser reflectivity, and time resolved x-ray diffraction (XRD). Time resolved laser reflectivity and XRD show that exposure to various etch and ash chemistries significantly reduces the crystallization speed while the transition temperature from the rocksalt to the hexagonal phase is increased. XPS and XAS attribute this to the selective removal and oxidization of N, Ge, Sb, and Te, thus altering the local bonding environment to the detriment of device performance. [ABSTRACT FROM AUTHOR]

Chemically ordered, self-assembled FePt nanoparticle arrays with high magnetic anisotropy are considered as a candidate medium for data storage beyond 1 Tbit/in². We report comprehensive structural and magnetic studies on thin (three-layer) assemblies of polyethylenimine (PEI) and 4 nm Fe58Pt42 nanoparticles using x-ray diffraction, small angle neutron scattering, and magnetometry. We show that prior to annealing FePt nanoparticles in the PEI-FePt assembly consist of a metallic magnetic core surrounded by a weakly magnetic or nonmagnetic shell. High temperature annealing creates the desired L 10 chemical ordering and results in high coercivity FePt nanoparticles. However, we find that the high temperatures necessary to establish full chemical ordering leads to particle sintering and agglomeration. Understanding the magnetic and physical properties of these assemblies allows future research directions to be clarified for nanoparticle arrays as data storage media. [ABSTRACT FROM AUTHOR]

The magnetic field required to reverse a Co/Pd multilayer film with perpendicular anisotropy is greatly increased when the film is deposited onto patterned islands. It is proposed that for the larger islands, reversal is governed by a nucleation event, which has Stoner-Wohlfarth (SW) characteristics, followed by rapid domain wall motion.

The Silicide formation and particle size growth in high-temperature-annealed, self-assembled FePt nanoparticles is discussed. Silicide formation as a result of a chemical reaction with the native oxide or Si substrate leads to a substantial drop in magnetization for T(sub anneal)>650 degree C.

The fabrication and magnetic characterization of 30 nm diam single domain islands with perpendicular anisotropy on patterned thermally oxidized Si substrates is discussed. The reversal behavior of the patterned islands was found to be different from that of the continuous films with a large increase in both switching field and switching field distribution.

Presents a study that examined the growth and physico-chemical characteristics of strontium erbium fluoride luminescent thin film grown on indium phosphide (100) substrates. Preparation of the thin films; Examination of the composition of the thin films; Analysis of the structure and texture of the thin films.

Presents a study that evaluated the luminescence of strontium erbium fluoride solid solution thin film grown on indium phosphide substrates. Analysis of the photoluminescence intensities under visible and infrared domain; Examination of the luminescence of the samples under low and room temperature; Assessment of the cathodoluminescence of the samples.

The magnetic field required to reverse a Co/Pd multilayer film with perpendicular anisotropy is greatly increased when the film is deposited onto patterned islands. The variation of the reversal field with Co thickness demonstrates that the island switching field is determined principally by the anisotropy. For sufficiently small islands the reversal field is close to that calculated using the Stoner-Wohlfarth (SW) model and these small islands show the expected SW angle dependence. A similar SW angle dependence is also observed for the larger islands. We propose that for the larger islands reversal is governed by a nucleation event, which has SW characteristics, followed by rapid domain wall motion. [ABSTRACT FROM AUTHOR]

Magnetically isolated single domain islands with perpendicular anisotropy have been prepared by depositing Co/Pd multilayer films on prepatterned sub-50 nm SiO2/Si islands. The island arrays were fabricated by both direct write electron beam lithography and nanoimprinting. Nanoimprinting allows the creation of large area, 4 mm×4 mm, samples appropriate for characterization by conventional measurement techniques. Magnetic force microscopy and vibrating sample magnetometry showed that the reversal behavior of the patterned islands is quite different from that of the continuous films with a large increase in both switching field and switching field distribution. Recording on island arrays with a periodicity of 100 nm, produced from prepatterned substrates, was demonstrated using a quasistatic tester. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]