bluuebunny/crossref_metadata_2025 huggingface dataset:
Solid-State NMR Studies of the Bonding Structure of Diamondlike Amorphous Carbon Films
Authors: Holl Susan M. , Johnson Robert D. , Novotny Vlad. J. , Williams Jeffrey L. , Caley Catherine E. , Hoinkis Mark , Jones Robert E.
Published: April 2011

Amorphous carbon films are (a-C:H) of interest because of their useful physical properties. They are extremely hard and chemically inert, resisting degradation by both acids and alkalis. They are insoluble and can be conformably coated onto virtually any substrate. These properties make the films ideal protective coatings on magnetic disks and tools. We have studied several thin (one to two micron) films prepared by plasma enhanced chemical vapor deposition with varying radiofrequency fields strengths to determine structural differences at the atomic level. Several properties of the films, such as hardness and wear rate, are dependent on deposition power. We have found that the sp2/sp3 ratio increases with increasing deposition power. Thus, films that are harder are more “graphitic” and less “diamondlike”. The films studied here contain 11–16 atomic percent hydrogen, most of which is associated with sp3 carbon sites. At least two distinct phases of hydrogens exist. Variable temperature studies reveal that, in contrast to amorphous hydrogenated silicon, proton linewidths in carbon films are temperature dependent, suggesting some molecular motion is present at room temperature.
Application of Desorption Mass Spectrometry to Molecular Beam Epitaxy
Authors: Evans Keith R.
Published: April 2011

Molecular beam epitaxy (MBE) is the most powerful crystal growth technique available in terms of the range of structures which can be produced. However, further advances in MBEprocess monitoring and control are required to produce the most demanding structures. Also, process yield, cost, and throughput must be improved for MBE to gain in production worthiness. Because of these issues, there currently is much research activity focusing on the development of advanced in-situ sensors for improved growth parameter monitoring and control. Desorption mass spectrometry (DMS) is an in-situ sensor technique for detecting species leaving the substrate during MBE growth processing. Since in general all surface processes affect desorption rates, and all growth parameters affect surface processes, DMS can be utilized to monitor a variety of MBE growth parameters and phenomena. Theimplementation of simple feedback techniques which link DMS error signals to changes in one or more growth parameters then provides for continuous control of desorption rates. This paper reviews some of the most recent accomplishments in the application of DMS forimproved growth parameter monitoring and control. Additionally, anticipated future directions in the application of DMS to epitaxial growth are discussed.
Materials Issues in Molecular Beam Epitaxy
Authors: Tsao J.Y.
Published: April 2011

The technology of crystal growth has advanced enormously during the past two decades; among those advances, the development and refinement of molecular beam epitaxy (MBE) has been among the most important. Crystals grown by MBE are more precisely controlled than those grown by any other method, and today form the basis for many of the most advanced device structures in solid-state physics, electronics and optoelectronics.

In addition toits numerous device applications, MBE is also an enormously rich and interesting area ofmaterials science in and of itself. In this paper, we discuss a few examples of some of these materials issues, organized according to whether they involve bulk, thin films, orsurfaces [1].
Non-Contact Temperature Measurement with Infrared Interferometry
Authors: Hung Steven C. H. , Dong Haike K. , Tu Charles W.
Published: April 2011

We have successfully utilized the temperature dependence of the refractive indices of various substrates (GaAs and InP) in detecting their temperature variations. The detectionwas accomplished by injecting a beam of HeNe laser (1.15 μm) toward a double-sidepolished substrate. An interference pattern developed among the reflected laser beams, and the actual temperature increment/decrement could be deduced from the interference maxima and minima. The method was first calibrated inside a diffusion furnace from room temperature up to 200ºC, and the detection resolution was found to reach as high as ±0.7ºC. The same measurement setup was later used on the temperature calibration of a substrate heater in a molecular beam epitaxy (MBE) growth chamber, and was finally used to detect surface temperature change during Ar+ laser assisted metalorganic MBE (MOMBE) growth. Because a direct contact is unnecessary and only the relative signal intensity is needed, this low-cost method can be applied to any otherexperiments in a fairly straightforward manner.
Study of Monocrystalline Structure of GaAs/Si Grown by VPE
Authors: Rong Zhang , Youdou Zheng , Yong Yan , Duan Feng , Shanxiang Huang
Published: April 2011

A single crystal GaAs/Si heterostructure has been fabricated using the “two step” version of the traditional halogenide VPE technique. The X-ray diffraction spectroscopy, the high resolution electron microscopy observation and the Raman scattering spectroscopy have been used to analyze the structure of the GaAs epitaxial film on Si, while the X-ray photoelectron energy spectroscopy has been used to determine the chemical structure of the GaAs epilayer. The results indicate that the epilayer is a stoichiometric GaAs single crystal film.
Acceptor Concentration Control of p-ZnSe using N2+He Gas Plasma by Molecular Beam Epitaxy
Authors: Kobayashi Masakazu , Yoshikawa Akihiko
Published: April 2011

Nitrogen and helium mixed gas plasma was used to grow p-ZnSe. Using the mixed gas, the acceptor concentration could be controlled from 6x1016 to 7x1017 cm−3 while films doped using the nitrogen plasma exhibited the acceptor concentration of 3x1017 cm−3. Doping characteristics such as the acceptor concentration and the PL properties depend on the gas mixing ratio and the rf power. Plasma spectroscopy was used to characterize the variety of the species in the plasma. Although the variety of the nitrogen related peaks in the spectrum were not significantly affected by the gas mixing, several peaks (for example 745nm and 825nm) showed intensity variation that was similar to the acceptor concentration variation with respect to the N2 and He gas mixing ratio.
MOVPE Growth and optical characterization of high-quality ZnSe-ZnS superlattices using a novel zinc adduct precursor
Authors: Briot O. , Blasio M. Di , Cloitre T. , Briot N. , Bigenwald P. , Gil B. , Averous M. , Aulombard R. L. , Smith L. M. , Rushworth S. A. , Jones A.C.
Published: April 2011

A novel zinc precursor adduct tetramethylmethylene diamine: dimethylzinc (TMMD:DMZn) has been used to grow ZnSe-ZnS strained layer superlattices by low pressure MOVPE at 300'C. The use of this new precursor leads to improved material purity and lower homogeneous gas phase premature reaction than in the case of dimethylzinc. Optical characterization has been made between liquid helium and room temperature. The 2K photoluminescence lines range between 2.85 eV and 3.15 eV. The 2K photoluminescence is characterized by a linewidth at half maximum ranging from 13-45 meV. Additional reflectivity and photoreflectance experiments have been carried out to measure light-hole excitons. A variational calculation of the Rydberg energies has been performed using a sophisticated trial function. The experimental data is in agreement with the theoretical value when a small conduction band offset is used.
Van der Waals Epitaxy of GaSe on GaAs(111)
Authors: Rumaner L. E. , Ohuchi F.S.
Published: April 2011

Although heteroepitaxy of lattice-matched and lattice-mismatched materials leading to artificially structured materials has resulted in impressive performance in various electronics devices, material combinations are usually limited by lattice matching constraints. A new concept for fabricating material systems using the atomically abrupt and low dimensional nature of layered materials, called van der Waals epitaxy (VDWE), has been developed. GaSe (Eg = 2.1 eV) has been deposited on the three dimensional surface of GaAs (111) using a molecular beam deposition system. GaSe was evaporated from a single Knudsen source, impinging on a heated substrate. Even with a lattice mismatch of 6% between the substrate and the growing film, good quality single crystal films were grown as determined by RHEED. The films have further been analyzed using a complementary combination of XPS and X-ray reflectivity.
Photoluminescence Spectroscopy and Rutherford Backscattering Channeling Evaluation of Various Capping Techniques for Rapid Thermal Annealing of Ion-Implanted ZnSe
Authors: Allen E.L. , Zach F.X. , Yu K.M. , Bourret E.D.
Published: April 2011

We report on the effectiveness of proximity caps and PECVD Si3N4 caps during annealing of implanted ZnSe films. OMVPE ZnSe films were grown using diisopropylselenide (DIPSe) and diethylzinc (DEZn) precursors, then ion-implanted with 1 × 1014 cm−2 N (33 keV) or Ne (45 keV) at room temperature and liquid nitrogen temperature, and rapid thermal annealed at temperatures between 200°C and 850°C. Rutherford backscattering spectrometry in the channeling orientation was used to investigate damage recovery, and photoluminescence spectroscopy was used to investigate crystal quality and the formation of point defects. Low temperature implants were found to have better luminescence properties than room temperature implants, and results show that annealing time and temperature may be more important than capping material in determining the optical properties. The effects of various caps, implant and annealing temperature are discussed in terms of their effect on the photoluminescence spectra.
Epitaxial Growth and Characterization of the Ordered Vacancy Compound CuIn3Se5 on GaAs (100) Fabricated by Molecular Beam Epitaxy
Authors: Nelson Art J. , Bode M. , Horner G. , Sinha K. , Moreland John
Published: April 2011

Epitaxial growth of the ordered vacancy compound (OVC) CuIn3Se5 has been achieved on GaAs (100) by molecular beam epitaxy (MBE) from Cu2Se and In2Se3 sources. Electron probe microanalysis and X-ray diffraction have confirmed the composition for the 1-3-5 OVC phase and that the film is single crystal Culn3Se5 (100). Transmission electron microscopy (TEM) characterization of the material also showed it to be single crystalline. Structural defects in the layer consisted mainly of stacking faults. Photoluminescence (PL) measurements performed at 7.5 K indicate that the bandgap is 1.28 eV. Raman spectra reveal a strong polarized peak at 152 cm−1, which is believed to arise from the totally symmetric vibration of the Se atoms in the lattice. Atomic force microscopy reveals faceting in a preferred (100) orientation.
GaAs/AlGaAs Multiquantum Well Infrared Detector Array with 6.0 μm Response Width
Authors: Li Jin-Min , Zheng Hai-Qun , Zeng Yi-Ping , Kong Mei-Ying
Published: April 2011

lO×16 GaAs/AlGaAs quantum well infrared detector arrays with peak responsivity at 9.3μm have been achieved with front-side normal illumination based on a waveguide of doubly periodic grating coupler. The detector array with a wideband response from 4.2μm to 10.3μm is demonstrated by optimizing the quantum well structures and device processes. A peak detectivity D*λ =2.9×1010 cmHz1/2 /W and high a responsivity Rp=0.37A/W have been obtained at λp=9.3μm and T=77K. The dark current densities of the detectors in the array were smaller than 6.2×10−6 A/cm2 with the detectors biased (Vb=3.2V) for maximum detectivity.
A Study of the Surface Texture of Polycrystalline Phosphor Films Using Atomic Force Microscopy
Authors: Revay R. , Schneir J. , Brower D. , Villarrubia J. , Fu J. , Cline J. , Hsieh T. J. , Wong-Ng W.
Published: April 2011

Stimulable phosphor thin films are being investigated for use as optical data storage media. We have successfully applied atomic force microscopy (AFM) to the measurement of the surface texture of these films. Determination of the surface texture of the films is important for evaluating the effect of surface quality on optical scatter. In other thin film material systems it has been found that the surface “bumps” revealed by AFM correspond to grains in the film. This is not the case for the stimulable phosphor films used in our study. We have determined the grain size of our phosphor films by transmission electron microscopy (TEM) and x-ray diffraction (XRD). The grain size from TEM and XRD does not correlate with the size of the AFM surface “bumps.” For example, in two of the five films studied, the XRD derived grain size varies by a factor of two but the size of the surface “bumps” remains the same. We conclude that the texture of the film surface is not directly determined by the grain size of the phosphor material.
Nanocrystalline Microstructures by Thin-Film Synthesis Methods
Authors: Libera M. , Smith D. A.
Published: April 2011

Nanostructured materials are being extensively studied because their ∼1–100nm grain size can dramatically affect properties. Most nanocrystalline synthesis methods produce particulate or flake. The process of consolidation also allows coarsening, contamination, and the introduction of porosity. The effect of nanocrystallinity on mechanical properties must be deconvoluted from these extrinsic artifacts. Most synthesis routes also produce small quantities of material. Reproducibly making enough specimens to explore more than a few properties is thus difficult. This paper describes thin-film processes to produce nanostructured materials. Thin-film deposition can easily produce many specimens, free from extrinsic artifacts, with identical composition and processing history. Many methods are now well established to study a variety of thin-film mechanical properties. We show examples of nanostructured films generated by controlling deposition and/or post-deposition processing.
Toward Realizing the Structure-Property Link in Polycrystalline Thin Films
Authors: Nichols C. S.
Published: April 2011

Many materials for engineering applications are used in polycrystalline form and contain grain boundaries with a range of structures and properties. However, most research on grain boundaries to date has focussed exclusively on symmetric coincidence site lattice interfaces. To go beyond descriptions for these simple interfaces and thence to an aggregate of grains and grain boundaries in a polycrystal will require a new approach. Here we discuss two models for properties of polycrystalline materials, including their advantages and drawbacks, and indicate the microstructural variables available to optimize properties.
Stability of Ruthenium-Silica Bilayer Structures
Authors: Weng-Sieh Zara , Nguyen Tai. D. , Gronsky Ronald
Published: April 2011

The microstructural evolution of ruthenium-silicon dioxide bilayer structures upon annealing is studied using transmission electron microscopy. SiO2/Ru/SiO2 structures, with thicknesses of 2/1/2 nm, 4/2/4 nm, 8/4/8 nm, and 20/10/20 nm, are formed by magnetron sputtering and annealed at 300 or 600°C. As-deposited films have grain sizes on the order of the Ru film thickness. After annealing at 600°C, significant grain growth is observed for all thicknesses, such that the final grain sizes are approximately 3 to 20x greater than the original film thickness. The largest increase in the average Ru grain size is observed for the 2 nm thick ruthenium film possibly due to the coalescence of Ru grains. The coalescence of the Ru particles in the 1 and 2 nm thick films results in the formation of lamellar Ru grains, which disrupts the contiguity of the Ru film. In all other cases, the increase in grain size is attributed to normal grain growth, but the formation of anomalous spherical grains is also observed.
Monocrystalline and Polycrystalline Thin Films Formed by Cobalt Ion Implantation in the Organic Substrate (Polyester)
Authors: Stepanov A. L. , Khaibullin R. I. , Abdullin S. N. , Osin Yu. N. , Khaibullin I. B.
Published: April 2011

The structure and phase composition of thin films formed by 40 KeV cobalt ion implantation into organic substrate (polyester) were studied by transmission electron microscopy in conjunction with electron diffraction. Varying current density and dose implantation over the range 0.3×1016 – 2.4×1017 cm-2 we obtained island-like cobalt films of different type as well as labyrinth-like structure at the highest dose value. The granulometric and morphologic parameters were derived from the micrographs of the investigated films. Both amorphous state and α-Co crystalline lattice of cobalt granules were established from electron diffraction patterns of synthesized films. Along with discontinuous films, we formed monocrystalline plates of α-phase cobalt under the determined implantation regimes and conditions. Cross-section images of synthesized films showed that films are of about 300 Å thick and buried at the depth of 150 Å from the principal surface of the polyester.
Kinetics of Interface Reactions in Polycrystalline Thin Films
Authors: Bormann Rüdiger
Published: April 2011

A quantitative description of the nucleation and growth kinetics determining the interface reactions between two phases is given. Particular focus is given to the understanding of the mechanisms causing the distinct phase selection occurring during the early stages of interface reaction. Thereby the microstructure of the parent phases and the new phases formed are also taken into account and discussed with respect to their influence on the phase selection. The conclusions are applied to the results of two model systems, Al-Ni and Zr-Ni.
High resolution studies of the solid state amorphization reaction in the ZrCo system with the atom probe/field ion microscope
Authors: Schneider Susanne , Busch Ralf , Samwer Konrad
Published: April 2011

The atom probe/field ion microscope is introduced as a new powerful investigation device to study the early stages of the solid state amorphization reaction (SSAR). A bilayer of Zr and Co was condensed under UHV conditions on W wire tips and analyzed in a field ion microscope (FIM) combined with an atom probe (AP). The reaction of Co with Zr has been studied at room temperature. FIM pictures and AP analysis have shown that even at low temperatures an amorphous phase is formed at the Zr/Co interface and in the Zr grain boundaries. In these areas concentration profiles have been taken on a nanometer scale. Most likely, the extended solid solution of Co found in α- Zr grain boundaries causes the formation of the amorphous phase. Further, Rutherford backscattering spectrometry (RBS) suggests that even point defects and dislocations at the surface of an α- Zr single crystal are sufficient to initiate the SSAR between a polycrystalline Co layer vapour- deposited onto that single crystal.
The Earliest Stage of the Solid State Amorphization Reaction in the Zr-Co System
Authors: Busch Ralf , Gaertner Frank , Schneider Susanne , Bormann Rüdiger , Haasen Peter
Published: April 2011

Based on atom probe field ion microscopy (AP/FIM) studies, electromotive force (EMF) measurements and CALPHAD calculations we discuss the earliest stage of the solid state amorphization reaction (SSAR) in Zr/Co-layers. The AP measurements show that two amorphous phases are formed at the Zr/Co interface from the early stages of the reaction. The metastable two phase field between these amorphous phases is shown by direct measurement of the chemical potential of Zr in amorphous co-sputtered ZrCo alloys by the EMF method. The comparison between the atom probe data and the CALPHAD calculation shows that the interfaces between the different layers are far away from metastable equilibrium in the beginning of the reaction. The amorphous phase formation at the Zr/Co interface and in the hcp-Zr grain boundary is preceded by a supersaturation of the hep ZrCo solid solution that transforms polymorphically into the amorphous state.
Effects of Microstructure and Crystallography on the Magnetic Properties of CoCrPt/Cr Thin Films
Authors: Choe G. , Chung S.J.
Published: April 2011

The effects of grain morphology and crystallography on the magnetic properties of CoCrPt/Cr thin films were investigated as a function of sputtering parameters of CoCrPt thin films. Cross sectional TEM exhibited strong separation of Co grains with increasing argon sputtering pressure, resulting in reduced exchange coupling and increased coercivity. Most Co grains sputtered at high pressure were separated by 10 to 20 Å thick boundaries, possibly due to the enhanced scattering of argon ions by sputtering particles and thus the observed higher content of Pt in the deposited films. The application of substrate bias greatly decreased the Co grain separation and the nonmagnetic grain boundary disappeared by -200 V bias sputtering, resulting in increased exchange coupling. The bias sputtered CoCrPt thin films decreased their grain size and increased epitaxial growth on Cr layer and also (1010) texture. The magnetic field required to saturate the film increased significantly with increasing substrate bias, possibly due to the induced residual stress in the bias sputtered films.
HCP-FCC Phase Transition in Co-Ni Alloys Studied With Magneto-Optical Kerr Spectroscopy
Authors: Carl A. , Weller D. , Savoy R. , Hillebrands B.
Published: April 2011

We have studied 100nm thick electron beam evaporated Co1-xNix alloy films in the composition range 0 ≤ x ≥ 1 using magneto-optical spectroscopy and magnetic anisotropy measurements. For films with x ≈ 0.2 we have also investigated the dependence of these quantities on the growth temperature, which was varied in the range 27 ≤ TG ≥ 408°C. Both as function of the Ni content x and the growth temperature TG we observe the anticipated hcp → fcc phase transition, e.g. by monitoring the magneto-crystalline anisotropy constant Ku, 1, which changes continuously from values of ≈ 0.3MJ/m3 for Co rich hcp alloys (0 ≤ x ≥ 0.25) to ≈ -0.05MJ/m3 for Ni rich fcc alloy films, in good agreement with bulk literature data. The new and most striking result, however, is observed in the polar magneto-optical Kerr and ellipticity spectra, which were measured in the photon energy range 0.8 ≤ hv ≥ 5.5eV. Changes by up to about 40% in Kerr rotation for films of constant composition and magnetization are observed when the structure changes from hcp → fcc. This demonstrates the sensitivity of magneto-optical effects to structural changes, making Kerr spectroscopy a useful electronic and physical structure probe.
Giant Magnetoresistance in As-Sputter-Deposited Au/NiFe Multilayer Thin Films
Authors: Lee W. Y. , Gorman G. , Savoy R.
Published: April 2011

Giant magnetoresistance with low saturation fields (Hs’s) is reported in Au and permalloy (Ni0.82Fe0.18) or Co-doped permalloy multilayer thin films as-deposited on Ta-overcoated Si and glass substrates. A ΔR/R as high as 4.0% with ≈25 Oe Hs was observed at 295 K for the film consisting of 10 layers of 24 Å Au/13 Å Ni0.82Fe0.18 deposited on a 3 Å Ta-overcoated glass at 50 °C. A Hs value as low as ≈20 Oe with a 15% smaller ΔR/R has been observed for the films with a thicker (e.g., 50 Å) Ta underlayer. Magnetic hysteresis loops of these films indicate the presence of antiferromagnetic exchange coupling between the Ni0.82Fe0.18 layers. This exchange coupling is much smaller for the multilayer films without the Ta underlayer, resulting in a 6x smaller ΔR/R and lOx larger Hs observed for these films. Results of x-ray diffraction analysis indicate stronger (111) texturing for the multilayer films with a Ta underlayer, consistent with the stronger antiferromagnetic coupling between the the Ni0.82Fe0.18 layers in the film. The addition of 2–10 % Co moderately increases the ΔR/R value, but also increases substantially the Hs (up to ≈200 Oe).
Characterization of Sol-Gel Derived (Pb,Ba)(Zr,Ti,Nb)O3 Thin Films for Optical Waveguide Development
Authors: Baude P. F. , Wright J. S. , Ye C. , Francis L. F. , Polla D. L.
Published: April 2011

(PbBa)(ZrTiNb)03 thin films and powders have been prepared using the sol-gel technique. Solutions were synthesized in 2-methoxyethanol based upon our previous PZT solution preparation. Three different approaches were used for incorporating barium into PZT alkoxide solutions. Thermal analysis and x-ray diffraction results indicated that barium methoxypropoxide gave the best results. PBZTN (71% Pb and 71% Zr) was deposited onto sapphire substrates as well as oxidized silicon substrates. Optical transmission measurements showed greater than 80% transmission for wavelengths longer than 400 nm. Films with thickness of 3000 Å on sapphire exhibited a refractive index of 2.19 at λ=633 nm.
Texture Variations in Sol-Gel Derived PZT Films on Substrates with Platinum Metallization
Authors: Gardeniers J.G.E. , Elwenspoek M. , Cobianu C.
Published: April 2011

Metalorganic precursor solutions of composition Zr : Ti = 0.53 : 0.47 were used to spin-cast PZT layers on sputtered Pt films. After annealing at temperatures of 550 °C - 800 °C, the PZT films of tetragonal perovskite structure reproducibly showed different textures and surface morphologies, depending on whether or not a Ti layer was used as an adhesion layer for the Pt film. The texture differences were found to be independent of annealing treatment. It is argued that the observed texture differences are caused by a change in Pt-PZT interface composition, resulting from the diffusion of Ti into the Pt film during annealing; X-ray diffraction of an annealed Pt/Ti/SiO2/Si film combination provided evidence for a compound Pt3Ti. Annealing at 850 °C caused severe diffusion of Ti from the metal layer into the PZT film, leading to a tetragonal PZT layer with lattice constants corresponding to a Zr : Ti ratio of 30 : 70.
Growth and Characterization of Ba0.5Sr0.5TiO3 Thin Films on Si (100) By 90° Off-Axis Sputtering
Authors: Hou S. Y. , Kwo J. , Watts R. K. , Werder D. J. , Shmulovich J. , O'Bryan H. M.
Published: April 2011

We have studied BaxSr1-xTiO3 (BST) thin films (x=0.5) grown on Si (100) with and without a Pt/Ta barrier layer using 90° off-axis RF sputtering. The growth conditions were optimized according to film crystallinity, stoichiometry, and dielectric properties. Polycrystalline BST films with strong (100) texture were obtained via growth on Si (100). The measured dielectric constant from these films was low, presumably because of the parasitic effect of native oxide at BST/Si interface as revealed by TEM. On the other hand, BST films grown on Si with Pt/Ta barrier layers have crystallinity inferior to that on bare Si as determined by X-ray diffraction. Nevertheless, the best BST films on Pt/Ta layers still have good dielectric properties with dielectric constant exceeding 330, leakage current density < 1×10−6 A/cm2 (±1 V), and loss tangent 0.05 at 1 MHz.
Preparation and Property Characterization of Oriented PLZT Thin Films Processed Using Sol-Gel Method
Authors: Sung Yoon Dae , Jung Kim Chang , Sung Lee Joon , Gi Choi Chaun , Jong Lee Won , No Kwangsoo
Published: April 2011

Highly preferentially oriented lead lathanum zirconate titanate(PLZT) thin films were fabricated on various substrates using the spin coating of metal organic solutions having the composition of (9/50/50) and (10/0/100). The substrates used in this study were SrTiO3(100), MgO(100), r-plane sapphire, PLT-coated glass, and Pt/Ti/MgO substrates. The films were heat-treated at 600°C and 700°C using the direct insertion method. The phases and the orientation of the PLZT thin films were examined using X-ray diffraction(XRD). Pole figure and X-ray rocking curves were measured to study the film orientation. The films were grown with (100), (110), and (001) plane being parallel to the surfaces of SrTiO3, sapphire, and Pt/Ti/MgO, respectively. The dielectric and optical properties of both the oriented films and the noncrystalline films were measured and discussed.
RuO2 Thin Films as Bottom Electrodes for High Dielectric Constant Materials
Authors: Yoshikawa K. , Kimura T. , Noshiro H. , Ohtani S. , Yamada M. , Furumura Y.
Published: April 2011

Ruthenium dioxide (RuO2) thin films are evaluated as bottom electrode for dielectric SrTiO3. It was found that a RuO2 (50nm) / Ru (20nm) barrier layer on a Si substrate is effective as an oxygen barrier layer and as a metal diffusion barrier layer for sputter deposited SrTiO3 films at substrate temperature of 450°C. To test suitability for high temperature processes, RuO2/Ru electrodes were annealed in air at 600°C. 100nm-thiick RuO2 was sufficient to prevent oxygen diffusion. After annealing in the same condition, the leakage current of sputter deposited SrTiO3 (150nm) on RuO2(50nm) / Ru(50nm) was 7.6 × 10 −9 (A/cm2) at 2V.
Enhanced Mechanical Hardness in Compositionally Modulated Fe/Pt and Fe/Cr Epitaxial Thin Films
Authors: Daniels B. J. , Nix W. D. , Clemens B. M.
Published: April 2011

The hardnesses and elastic moduli of sputter-deposited Fe/Pt and Fe/Cr multilayers grown on MgO(001) are evaluated as a function of composition wavelength, Λ. Structural determination by x-ray diffraction showed these films to be oriented in the plane as well as out of the plane. The mechanical behavior of these films was evaluated by nanoindentation. The combination of nanoindentation and x-ray diffraction is an attempt to determine the structural underpinnings of the mechanical behavior of these metal multilayer systems. For both systems there is no observed enhancement in the elastic modulus (the so-called supermodulus effect) across a wide range of bilayer spacings. Nanoindentation results show that for Fe/Pt multilayers, the hardness is enhanced over that expected from a simple rule of mixtures by a factor of approximately 2.5, with a maximum enhancement of 2.8 times this value at a wavelength of 25 Å. This enhancement in hardness occurs for bilayer spacings from 20 Å to 100 Å and is not a strong function of Λ over this range. Results for Fe/Cr multilayers show a hardness enhancement over a similar wavelength range of approximately two times the rule of mixtures value, with a maximum enhancement of 2.2 times this value at a wavelength of 40 Å. The larger hardness enhancement in the Fe/Pt system may be due to the structural barrier (FCC/BCC) to dislocation motion between the two materials. The dominant mechanism responsible for the hardness enhancement in Fe/Pt and Fe/Cr multilayers is not yet known, however three models for dislocation interactions which could account for the hardness enhancement in these multilayers are discussed.
Microstructure - Stress - Property Relationships in Nanometer Ge/C Multilayers
Authors: Lu Xiang , Nguyen Tai D. , Underwood James H.
Published: April 2011

A series of sputtered as-prepared and annealed Ge/C multilayer structures with periods ranging from 2 to 8 nm has been studied with high resolution transmission electron microscopy (HRTEM), x-ray scattering, and stress measurement techniques. Ge/C multilayers have potential applications as normal incidence reflective mirrors near 4.4 nm wavelength. The reflectivity and stress in these structures depend on the microstructural evolution of the component layers. The as-prepared structure of both Ge and C layers appear amorphous from TEM imaging and diffraction. Annealing at 500°C for 60 minutes leads to crystallization of the Ge layers. As the phase diagram indicates, no carbide compound has been found. X-ray scattering reveals that the multilayer period expands by as much as 10% after annealing. Both TEM images and x-ray profiles suggest that the layer structures remain well-defined upon annealing. In-situ stress-temperature measurements directly show the Ge/C multilayer microstructure evolution path. X-ray measurements show that the structures with periods near 2 nm undergo a significant improvement on optical performance with annealing. The physical mechanisms that may have caused the optical enhancement are discussed. Correlation of the stress evolution in the multilayers and in individual layers during annealing, and their relationships to the microstructures and optical properties are examined.
Polycrystalline Communication Links: Microelectronic Chip Interconnects
Authors: Sullivan Timothy D.
Published: April 2011

All microelectronic chip interconnects are composed of polycrystalline films with properties that vary discretely with grain orientation. Techniques for dealing with this variation are developing as diminishing dimensions accentuate the effects of grain orientation. Variations in metallization microstructure affect mass transport and median failure time for metallization wearout mechanisms. Stability of adhesion layers, barrier layers and redundant conduction layers is influenced by the microstructure of the films in contact with each other. Intermetallic reactions, which are of no concern with single-level metallization, can become significant for multi level metallizations. Ti/AI systems provide typical examples of these trends.
Characterization of Textured Aluminum Lines and Modelling of Stress Voiding
Authors: Wardle S.C. , Adams B.L. , Nichols C.S. , Smith D.A.
Published: April 2011

It is well known from studies of individual interfaces that grain boundaries exhibit a spectrum of properties because their structure is misorientation dependent. Usually this variability is neglected and properties are modeled using a mean field approach. The limitations inherent in this approach can be overcome, in principle, using a combination of experimental techniques, theory and modeling. The bamboo structure of an interconnect is a particularly simple polycrystalline structure that can now be readily characterized experimentally and modeled in the computer. The grain misorientations in a [111] textured aluminum line have been measured using the new automated technique of orientational imaging microscopy. By relating boundary angle to diffusivity the expected stress voiding failure processes can be predicted through the link between misorientation angle, grain boundary excess free energy and diffusivity. Consequently it can be shown that the high energy boundaries are the favored failure sites thermodynamically and kinetically.
Pulse-to-Pulse Laser Stability Effects on Multiple Shot Excimer Laser Crystallized a-Si Thin Films
Authors: Johnson R. I. , Anderson G. B. , Boyce J. B. , Fork D. K. , Mei P. , Ready S. E.
Published: April 2011

Laser crystallized amorphous silicon thin films on quartz exhibit a peak in the grain size, electron mobility and the Si (111) x-ray intensity as a function of the laser fluence, substrate temperature, film thickness, and the number of laser shots per unit area. The peak in grain size has also been shown to be dependent: on the stability of the pulse-to-pulse laser energy density, particularly at high shot densities. The shape of the distribution profile of the pulse-to-pulse laser fluence can significantly alter the grain growth at higher shot densities. The modified growth can be expressed by a simple model based on the mean and standard deviation of the laser energy density relative to the characteristic fluence at which the grain size, mobility, and Si (111) x-ray intensities are maximized.
Improvement of Grain Size by Crystallization of Double-Layer Amorphous Silicon Films
Authors: Moon Dae Gyu , Lee Jeong No , Im Ho Bin , Ahn Byung Tae , Nam Kee Soo , Kang Sang Won
Published: April 2011

We investigated the solid phase crystallization (SPC) behavior of 1000 Å amorphous Si (a- Si) films deposited by plasma enhanced chemical vapor deposition (PECVD) at various temperatures and were able to enhance the grain size of the crystallized polysilicon films using double layers of a-Si filns. The deposition temperature of monolayer a-Si films varied from 200 to 400 °C and the films were recrystallized at 600 °C in nitrogen. As the deposition temperature increased, the incubation time was decreased and both the nucleation rate and growth rate were increased. Especially, the nucleation rate strongly depended on the deposition temperature.

Since the Si-SiO2 interface provides a large number of nucleation sites, it is desirable to suppress nucleation at the interface. As an idea we employed a structure with double layer a-Si films. The bottom a-Si layer deposited at lower temperature could suppress the nucleation at the Si-SiO2 interface while the top a-Si layer deposited at higher temperature could nucleate with a smaller number of nucleation sites. The incubation time and transformation behavior were determined by the deposition temperature of the top layer. As an example, the grain size of the double layer film deposited sequentially at 150 °C and 200 °C enhanced to 1.8 μm while that of the monolayer film deposited at 200 °C was 1.4 μm.
High Deposition Rate Pecvd Processes For Next Generation Tft-Lcds
Authors: Westendorp J. F. M. , Meiling H. , Pollock J. D. , Berrian D. W. , Laflamme A. H. , Hautala J. , Vanderpot J.
Published: April 2011

The demand for lower cost per panel in TFT-LCD production is driving the PECVD market to deposition systems that combine high throughput and uptime with high yield. Today it is generally believed that a multichamber system that combines a number of single-panel deposition chambers is the best way to achieve these goals.

For these PECVD systems to be economical, the deposition rate of a-Si:H, SiNx and SiO2 has to be in the 1200–1500 Å/min range. In 13.56 MHz parallel-plate glow discharge systems SiNx and SiO2 deposition rates exceeding 1500 Å/min are commonly achieved, whereas the deposition rate of a-Si:H is limited to 100–200 Å/min due to powder formation. Over the last 5 years significant progress has been made to increase the deposition rate of a-Si:H. Methods include the use of very-high-frequency glow discharge (VHF-GD) and pulsing of the rf discharge. However, substrate sizes never exceeded 100mm×100mm.

We have developed a multichamber PECVD system for TFT-LCD production where VHFGD is used to obtain uniform high deposition rates for (doped) semiconductors and insulators, such as a-Si:H, n+ a-Si:H, SiNx and SiO2 over areas as large as 470mm×370mm. Even at deposition rates well above 1200 Å/min hydrogen in a-Si:H is exclusively bound as monohydride. The optoelectronic properties of the films are at least as good as those of their 13.56 MHz counterparts and thus good-quality TFTs can be obtained. At the same time the number of added particles is low allowing for high production yields.
New Materials For Laser Repair Of Active Matrix Liqiuid crystal Displays
Authors: Comita Paul B. , Larson Carl E.
Published: April 2011

New materials have been developed for the repair of electrical open defects in AMLICD panel circuitry The metal-containing precursors are volatile, easily pyrolyzed to high purity conducting metal, and are decomposed at temperatures which will not damage the glass substrate or thin film circuitry. New materials have been developed for additive metal repair as well as additive passivation repair. The repair or data line metallurgy on prototype arrays has been achieved, resulting in electrical resistances of the repaired interconnects which were comparable to those of unrepaired interconnects of identical geometry.
Alignment Of Smectic Liquid Crystal Molecules By Grated Glass And Silicon Substrates
Authors: Martínez-Miranda L. J. , Smela E. , Liu H.
Published: April 2011

We present the results of a study of the effect of photolithographed gratings on glass and silicon wafers on the alignment of smectic liquid crystal molecules. The gratings have periods in the range of 200nm − 200µm, and depths of up to 2µm. We found that smectic liquid crystals alignsharplyalong the gratings, depending on the temperature cycling method used in loading the sample. This result applies both to silicon gratings as well as glass gratings, despite the increased roughness observed in glass gratings. The quality of the alignment is uniform in the range 664nm − 24µm, and breaks down outside this region, setting lower and upper boundaries for grating preparation.
Transparent Conducting Films Of GaInO3 By Sputtering
Authors: Kwo J. , Carter S. A. , Cava R. J. , Hou S. Y. , Phillips J. M. , Rapkine D. H. , Thomas G. A. , Dover R. B. Van
Published: April 2011

One of the critical components used in the display device is the transparent conducting electrode. A new candidate for the transparent conductor, GaInO3 containing a tetrahedrally coordinated Ga site was identified recently, and shows good promise of improved optical transmission in the blue wavelength over ITO due to a high band gap ˜3.3 eV. Thin films of GaInO3 with cation dopants Ge for Ga, and Sn for In, respectively, have been prepared using dc reactive magnetron sputtering. Among the growth parameters, oxygen partial pressure plays the decisive role in affecting the film quality. A post-anneal in H2-rich atmosphere at 300C effectively reduced the oxygen content and lowered the resistivity to ∼3.0 mΩ-cm; however, the final resistivity appears to be insensitive to cation dopant concentrations. Concurrently, Hall measurements indicated a carrier concentration in the mid 1019 range for all films. Our structural analysis by x-ray and SEM has suggested that a limited Sn solubility in the film to less than 5 %. Doping appears to be due both to oxygen vacancies and aliovalent ion substitutions. The optical transmission of this new material is indeed superior to ITO over the entire visible spectrum, especially in the green and blue wavelengths. More work is underway to identify appropriate dopants for attaining better film conductivity.
Mechanisms Of Liquid Crystal Alignment On Buffed Polyimide Surfaces
Authors: Kikuchi Hirotsugu , Logan J. A. , Yoon Do Y.
Published: April 2011

The surfaces of poly(amic acid) and cured polyimide films, subjected to different buffing and cure profiles, have been examined by atomic force microscopy (AFM). The ability of these buffed polymer surfaces to align nematic and chiral smectic C liquid crystals were also investigated. These studies show that the presence of microgrooves on buffed polymer surfaces are not necessary for alignment of liquid crystals. Rather, it is concluded that the liquid crystal alignment is mainly caused by the anisotropic intermolecular interactions between liquid crystal molecules and the polymer chains oriented by buffing. For the alignment of smectics, both the degree of order and mechanical properties of polyimide films are found to be important factors.
In-Situ Crystallization and Doping of a-Si Film by Means of Spin-On-Glass
Authors: Sakoda Tomoyuki , Kim Chang-Dong , Matsumura Masakiyo
Published: April 2011

A novel technique has been proposed for selective and in -situ excimer-laser crystallization and doping to thin poly-Si films. Dopant atoms are supplied, during the Si laser crystallization process, to the Si film on glass from the doped SOG (spin-on-glass) film coated on the top. Conductivity of the processed film was increased to more than 10S/cm from about 10−8S/cm of the starting film. This technique has been applied to the bottom gate amorphous-Si TFTs with self-aligned poly-Si source and drain. The electron field-effect mobility was 1.0cm2/Vs and the on/off current ratio was more than 106. No parasitic effects were observed, and the hole conduction was effectively. This in-situ crystallization and doping technique can also be applied to the top gate a-Si TFT process.
High Mobility Non-Hydrogenated Low Temperature Polysilicon TFTs
Authors: Plais F. , Legagneux P. , Kretz T. , Stroh R. , Huet O. , Pribat D.
Published: April 2011

We have fabricated polysilicon (poly-Si) thin film transistors (TFTs) using a standard 4-mask sequence, with self-aligned ion implantation for source and drain doping. The active layer was obtained by solid phase crystallisation of high purity Si2H6-deposited amorphous Si, whereas the gate oxide was synthesised by a novel plasma deposition technique, namely distributed electron cyclotron resonance plasma enhanced chemical vapour deposition (DECR PECVD). We have obtained high carrier mobilities (70 cm2V−1s−1 for electrons and 40 cm2V−1s−1 for holes) with an excellent uniformity and without the need for a post-hydrogenation treatment. Moreover, we show that the TFT characteristics are practically insensitive to hot carrier effects.
The Quasioptical Gyrotron, A High-Power, Tunable Source of Millimeter-Wave Radiation
Authors: Fliflet Arne W. , Fischer Richard P.
Published: April 2011

This talk will summarize the present state of the art of the quasioptical gyrotron (QOG), an alternative gyrotron configuration which has been under development primarily in the U.S. and Switzerland for heating fusion plasmas in tokamaks and other high-power millimeter-wave applications. The QOG features an open-mirror Fabry-Perot resonator instead of the conventional waveguide cavity used in conventional gyrotrons. This gives the QOG the potential for wide tunability, advantages for high-power operation, and facilitates the use of a depressed collector for spent electron beam energy recovery. An experimental QOG has been tuned from 85 to 130 GHz by varying the applied magnetic field. QOGs have produced peak powers up to 600 kW for 13 μs pulses and 100 kW for 10 ms pulses. Electronic efficiencies up to 22% have been achieved at 85 GHz, and operation with a depressed collector yielded an overall efficiency of 30%. The design of a multi-kW CW QOG tunable from 80 to 120 GHz is discussed.
Microwave Techniques for Measuring Complex Permittivity and Permeability of Materials
Authors: Guillon P.
Published: April 2011

A review of microwave techniques for measuring both complex permittivity and complex permeability of materials is given. It includes both resonant and reflection transmission methods for which limitations are discussed.
Numerical Modeling and Simulation of Electromagnetic Drying Processes
Authors: White Mikel J. , Gartside Paul J. , Iskander Magdy F.
Published: April 2011

Electromagnetic drying processes have been used in industrial applications for many years. New materials with different properties and structures have been recently developed which required the development of new drying systems capable of effectively drying the new materials. In this paper, we use Finite-Difference Time-Domain (FDTD) to model and simulate realistic electromagnetic drying processes including induction heating and RF drying. The power deposition patterns obtained from the FDTD code is also used in a finite-difference heat transfer code to evaluate the temperature distribution pattern and optimize rates of drying. Sample parameters used to analyze the RF drying and the induction heating processes include the sample conductivity, dielectric constant along with size, orientation and the geometric arrangement. Specifically, we analyzed the operating frequency, coil pitch, sample to coil diameter ratio, and the possible placement of multiple samples in an induction heating process. Effects investigated in a parallel plate RF drying system include: electrode spacing, electrode length and width, and the spacing between multiple samples. Results of electromagnetic power distributions and temperature patterns are presented.
Microwave Tower Absorption Profile in a Cylindrical Sample Contained in a Resonant Cylindrical Cavity
Authors: Jackson H. W. , Barmatz M. , Wagner P.
Published: April 2011

An analytic approach is used for evaluation of the microwave power absorption profiles in a lossy dielectric cylinder coaxially aligned in a cylindrical cavity. This approach, based on a cylindrical shell model, also determines the normal mode frequencies and fields. Absorption profiles inside the sample will be presented for resonant modes that are intrinsically angular independent. In addition, results will be presented for special modes that are not intrinsically angular independent, but produce angular independent absorption for time average values. This new development broadens the class of modes that can be used in heating materials when isotropy about an axis is needed. We demonstrate how this model can extend the application of cavity perturbation theory for determining dielectric constants to cylinders of larger diameter. Implications of these results for microwave processing of materials are also discussed.