bluuebunny/crossref_metadata_2025_split huggingface dataset:
Copper Vapor Laser Used in Etching and Deposition
Authors: Haba Belgacem , Hussey Brian W. , Gupta Arunava , Baseman Robert J. 
Published: March 2011

ABSTRACTWe have carried out experiments for etching manganese-zinc ferrite in aqueous KOH solution using a copper vapor laser. The high repetition rate (5-10 KHz), the high peak power (∼ 250 KW), and the short pulse length (24-30 ns) result in rapid etching of grooves with high aspect ratios. The depth of the grooves increased with laser power and slower scan speeds while, the width was limited to the laser beam focus. The etching process is believed to be purely thermal in nature and limited only by the removal of the molten material out of the grooves. The copper vapor laser was also used as a source for projection deposition of various metals on quartz substrate by a pyrolytic process. This system achieved patterns with finefeature sizes, good resolution, and metallic properties of the deposits. In this technique, both the spun-on organometallic films as well as LCVD were tried.
Excimer Laser-Assisted Etching of Silicon Using Chloropentafluoroethane
Authors: Russell S. D. , Sexton D. A. 
Published: March 2011

ABSTRACTLaser-assisted photothermal chemical reactions have been observed with silicon in a chloropentafluoroethane ambient using a KrF* laser at 248 nm. Etching occurs onlyif the incident fluence exceeds the melt threshold (∼0.75 J/cm2, with the melt duration determined by observing the change in silicon reflectance at 633 nm. Above the ablation threshold (∼2.2 J/cm2) increased surface roughness is observed. Etch rates -7 Å/pulse have been measured using both stylus profilometer and SEM cross-sectional techniques. The etch rate dependence on incident fluence, ambient pressure, doping concentration, crystal orientation and substrate temperature have been examined suggesting an adsorption limited thermal process. This process allows single step patterning of silicon devices in a non-corrosive environment.
Selective Silicon Epitaxy for Advanced Dram Structures
Authors: Bronner Gary B. 
Published: March 2011

ABSTRACTIn silicon microelectronics, memory cells and chips are used to develop the most advanced technology. In the future these chips will require three dimensional structures to achieve the needed density. This paper describes the use of selective silicon epitaxy to build truly three dimensional DRAM cells. The cell consists of a trench capacitor which is overgrown with single crystal silicon. A transistor and isolation are then built above the trench capacitor resulting in a cell that occupies the same area as the transistor alone. Fully functional memory cells have been built. The results show that selective silicon epitaxy is a realistic candidate for building three dimensional silicon devices.
Surface Reaction Mechanisms in Selected Area Epitaxy of II-VIs
Authors: Irvine Stuart J.C. , Hill H. , Hails J.E. , Pitt A.D. , Mullin J.B. 
Published: March 2011

ABSTRACTLaser-induced selected area epitaxy of CdTe thin films on GaAs substrates has been investigated and the role of vapour phase and surface reactions considered. Photo-enhanced growth rates of CdTe have been measured as a function of UV laser intensity and as a function of Cd to Te alkyl ratios. The growth rates are not simply determined by vapour phase photo-dissociation but also by a photolytic reaction on the surface. The latter enables good pattern definition where the growth rate is enhanced by the incident uv -radiation. The factors that determine the photo-enhancement are considered in the light of the Langmuir-Hinsheltwod model.
Laser Selective Area Epitaxy for the Potential of Optoelectronic Integration
Authors: Liu H. , Roberts J.C. , Ramdani J. , Bedair S.M. 
Published: March 2011

ABSTRACTWe report for the first time the dopant behavior in laser assisted selective epitaxy of device quality GaAs films. DMZn and H2Se were used as p-type and n-type dopants respectively. Uniform doping was achieved by introducing TMGa, AsH3 and dopant gases simultaneously and was accompanied by a decrease in growth rate for both Zn and Se doping. For planar doping, several Se planes were embedded in a GaAs layer by simultaneously introducing AsH3 and H2Se during the LCVD process. A sheet carrier concentration in the 1012 – 1013 cm−2 range was obtained for a single Se plane. Hall data of these films will be discussed. It was found planar doping results in better electrical properties and better growth rate control.
Reactive Ion Etching of In-Based III-V Semiconductors -Comparison of Cl and C2H6 Chemistries
Authors: Pearton S. J. , Chakrabarti U. K. , Baiocchi F. A. , Hobson W. S. 
Published: March 2011

ABSTRACTThe reactive ion etching of InP, InGaAs and InAlAs in CC12F2 /O 2 or C2H6 /H 2 discharges was investigated as a function of the plasma parameters pressure, power density, flow rate and relative composition. The etch rates of these materials are a factor of 3-5 times faster in CC12F2 /O 2 (∼600–1000 Å · min−1) compared to C2H6 /H 2(160–320 Å · min−1). Significantly smoother morphologies are obtained with C2H6 /H 2 etching provided the composition of the plasma is no more than 10 - 20% by volume of C2H6. At higher methane compositions, polymer formation increases leading to micromasking and rough surface morphologies. Sub-surface disorder is limited to <100 Å deep for both gas chemistries for plasma power densities of 0.85 W cm−2. The C2H6 /H 2 mixture leaves an In-rich surface in all cases, but this surface is free of any residual contamination, whereas the CC12F2/O2 chemistry leaves chloro-fluorocarbon residues approximately 20–50 Å thick on the surface of all three In-based materials.
Characterization of Sidewall Residue Film and Atomic Structure of the Trench Formed by BCI3/CI2 Reactive Ion Etching
Authors: Yun Sun Jin , Jeon Young-Jin , Lee Jeong Y. 
Published: March 2011

ABSTRACTThe silicon trench etching in BCl3/Cl2 reactive ion etching plasma leads to the intrinsic bonding damage, the permeations of etching species and impurities into silicon substrates, and the deposition of residue film on trench sidewall. The contaminations and the damages in trench were investigated by using high resolution transmission electron microscopy (HRTEM), secondary ion mass spectrometry (SIMS), and x-ray photoelectron spectroscopy (XPS). The microstructure of the rounded bottom surface showed that the surface region was distorted by 2 - 6 atomic layers and the trench etch was mainly limited by the physical sputtering-like mechanism. The damage in the silicon lattice consisted of prominent planar defects roughly confined to {110} and {111} planes. The thickness of sidewall residue film was 10 - 90 nm, which was thinner at deeper region of the trench, whereas that of residue film at the trench bottom was 1.5 - 3.5 nm. The SIMS results of no-patterned specimen presented that the permeation depths of boron and chlorine into the Si-substrate were about 40 and 20 nm, respectively. The presence of BxCly and Cl-related Si chemical states was identified from XPS analysis of the residue film.
Precursors to the Photo-Ablation of Sodium Trisilicate Glass Due to Uv Excimer Irradiation
Authors: Eschbach P. A. , Dickinson J. T. , Langford S. C. , Jensen L. C. , Pederson L. R. , Baer D. R. 
Published: March 2011

ABSTRACTOn polished sodium trisilicate glass surfaces, a fairly distinct threshold in laser fluence is observed to commence ablative etching. An incubation or induction effect is also seen where a series of laser pulses is required to induce etching. In this paper we examine features of the charged particle emission over a broader range of fluences (in particular, at lower fluences) to identify those factors which control the onset of etching. Laser--free electron heating is proposed as a dominant mechanism.
Low Temperature Laser Physical Vapor Deposition of Multilayered Thin Films
Authors: Biunno N. , Krishnaswamy J. , Sharan S. , Ganapathi L. , Narayan J. 
Published: March 2011

ABSTRACTWe have investigated the formation of various multilayer thin films by the laser physical vapor deposition technique. A multi stage target holder was constructed to perform all process steps in-situ; target/substrate cleaning, deposition, and annealing. The laser physical vapor deposition technique offers many advantages over conventional physical vapor techniques, such as, lower substrate temperature, microstructural control, and very low contamination levels. Film thickness can be controlled from near atomic to micron dimensions. A layer-by-layer (two dimensional) growth can be achieved, resulting in nonequilibrium structures. The films were analyzed using cross-section and high resolution transmission electron microscopy (TEM). The significant reduction in substrate temperature for the formation of high quality multilayer and epitaxial films opens up many new areas of applications requiring reduced thermal-budget processing.
Visible-Wavelength Laser Photodeposition of Cobalt Interconnects
Authors: Rothschild M. , Sedlacek J. H. C. , Shaver D. C. , Ehrlich D. J. , Bittenson S. N. , Edwards D. , Economou N. P. 
Published: March 2011

ABSTRACTCobalt interconnects were deposited with a cw visiblewavelength laser from gaseous Co2 (CO)8. The deposited material was high-purity Co, and its electrical resistivity was as low as 13 μΩ-cm (twice that of bulk resistivity). The deposition is initiated by photochemical decomposition of Co2 (CO)8, and therefore process parameters (pressure, power, writing speed) are insensitive to the optical and thermal properties of the substrate.
Laser Chemical Vapor Deposition of W on Si and SiO2/Si
Authors: Lin Jian-Yang , Allen Susan D. 
Published: March 2011

ABSTRACTDirect write of W on bare Si and native SiO2/Si substrates has been investigated in an laser chemical vapor deposition (LCVD) system. W deposits on bare Si surface via the Si and/or H2 reduction of WF6 were self-limited in thickness to 200 - 600 Å in both cases. Auger electron spectroscopic analysis showed that Si-H bonds could be poisoning the further growth of W. W deposits on native SiO2/Si were only obtainable via the H2 reduction of WF6 in our laser direct-write system. Our experimental kinetic study indicated that HF desorption from the surface is the rate-controlling step for W deposition via the H2 reduction of WF6. The as-deposited W line deposits were 2 - 10 μm wide, 0.2 - 6 μm thick with resistiiities in the range of 11 - 56 μΩ-cm. Growth rates as high as 2.2 mm/s have been achieved.
Very Thin 2D GaAs Films on Si During the Early Stages of Growth by MBE
Authors: Fenner D.B. , Biegelsen D.K. , Krusor B.S. , Ponce F.A. , Tramontana J.C. 
Published: March 2011

ABSTRACTGaAs samples deposited on Si by molecular beam epitaxy (MBE) with a graded thickness of 0–3 nm initially show the presence of a metastable two dimensional (2D) layer containing Ga and As. In the thicker regions of the wedge samples, islands (3D topography) form in the presence of the 2D sea, i.e., Stranski – Krastanov growth. Compositional profiles of these wedges were made with in situ Auger electron spectroscopy (AES) which has allowed the identification of at least four regimes of growth. Lattice images from cross – sectional transmission electron microscopy (XTEM) are consistent with the AES profiles. Substrate temperature during deposition of the films has a strong effect on film topography, as does the beam – flux ratio on film stoichiometry.
Electronic and Structural Study of Ni(Co) Silicide/Si(111) Contact System Studied by Soft X-Ray Emission Spectroscopy
Authors: Watabe H. , Nakamura H. , Iwami M. , Hirai M. , Kusaka M. 
Published: March 2011

ABSTRACTAn electron excited Si L2,3 valence band soft x-ray emission spectrum (SXES) for Ni(or Co)Si2 showed a clear modification from that for Si. From the SXES study, a fair amount of the Si(3s) valence band density of state (VB-DOS) is concluded to be included in the upper part of the VB-DOS for the transition metal(TM) disilicides due to the TM-Si bond formation, which is a clear contrast to proposals given so far. Non-destructive structural analysis of a NiSi2 (tens of nm)/Si(111) contact is also carried out successfully using the SXES.
Electron Spin Resonance Studies of Silicon Dioxide Films on Silicon in Integrated Circuits Using Spin Dependent Recombination
Authors: Jupina M. A. , Lenahan P. M. 
Published: March 2011

ABSTRACTThe technique of spin dependent recombination (SDR) allows the electron spin resonance (ESR) observation of electrically-active point defects in a single metal-oxide-semiconductor field-effect transistor (MOSFET) with surface areas of only 10-4 cm2 and Si/Si02 interface point defect densities of ∼1011/cm2. With SDR's enhanced sensitivity, devices with different processing details are explored. Differences in the E' spectra for variations in the oxidation processing are discussed.
Si(001) Molecular Beam Epitaxy: Enhanced Diffusion or Bonding?
Authors: Clarke S. , Wilby M.R. , Vvedensky D.D. 
Published: March 2011

ABSTRACTThrough application of a lattice model of the Si(001) surface, implemented in a Monte Carlo growth simulation we investigate the structural evolution of the Si(001) surface during molecular beam epitaxy. Particular emphasis is placed upon identifying the role of both enhanced diffusion and directional bonding.
Observations of Surfaces by Electron Microscopy During STM Operation
Authors: Spence J.C.H. , Knipping U. , Norton R. , Lo W. , Kuwabara M. 
Published: March 2011

ABSTRACTA scanning tunnelling microscope is described which operates inside a transmission electron microscope in the reflection mode. The device is used to study the mechanism of STM contrast in graphite and semiconductors. It allows for the observation of any strain during tunnelling, using the reflection electron diffraction contrast mechanism. The first results of our new transputer-based digital imaging system for STM are reported.
Direct Observation of A 7×7 Superstructure Buried at the Amorphous-Si / Si(111) Interface
Authors: Sakai Akira , Tatsumi Toru , Ishida Koichi 
Published: March 2011

ABSTRACTDirect imaging of a 7×7 superstructure buried at the interface between amorphous-Si and a Si(111) substrate was demonstrated by cross-sectional high resolution transmission electron microscopy (HRTEM). The electron diffraction pattern of the interface region in cross-section geometry showed diffuse streaks of fractional order which suggested the existence of the superstructure at the interface. The <110> cross-sectional HRTEM image showed the atomic configuration of the projected interface superstructure, which had a periodicity of 23 Å along the interface. Such periodicity corresponds to 7 times the 1/3{224} periodicity which is 3.3 Å at the interface. The interface atomic model of the buried 7×7 superstructure was also proposed by using the image matching technique between the experimental and computer simulated images.
Study of Interfacial Sharpness and Growth in (GaAs)M(AlAs)N Superlatihces
Authors: Gammon D. , Prokes S. , Katzer D.S. , Shanabrook B.V. , Fatemi M. , Tseng W. , Wilkins B. , Dietrich H. 
Published: March 2011

ABSTRACTX-ray diffraction, inelastic light scattering, photoluminescence and photoluminescence excitation spectroscopies have been employed to study the effects of growth conditions on the interfacial sharpness of GaAs/AlAs superlattices. In addition to describing which changes in the MBE growth procedures result in the sharpest interfaces, this study addresses the relative strengths and weaknesses of the experimental probes employed in the examination of interfacial irregularities.
A Study of Interfaces in GaAs/AlAs Superlatyices Using Phonons
Authors: Gammon D. , Shanabrook B.V. , Prokes S. , Katzer D.S. , Tseng W. , Wilkins B. , Dietrich H. 
Published: March 2011

ABSTRACTVibrational Raman scattering has been used in conjunction with luminescence, luminescence excitation spectroscopy, and x-ray diffraction to study the interfaces of GaAs/AlAs superlattices grown by MBE with and without growth interruptions at the interfaces. The confined LO phonon spectra clearly indicate that in the sample grown with growth interrupts at least one of the interfaces in each GaAs layer is truly smooth. In addition it is shown that the intensity of the interface phonons probed via Raman scattering is sensitive to the state of the interface.
The Electronic Structure pf Σ5 Grain Boundaries in CU
Authors: Sowa Erik C. , Gonis A. , Zhang X.-G. 
Published: March 2011

ABSTRACTWe present first-principles calculations of the densities of states (DOS's) of unrelaxed and relaxed twist and tilt grain boundaries (GB's) in Cu. The relaxed configurations were obtained through the use of the Embedded Atom Method (EAM), while the DOS's were calculated using the real-space multiplescattering theory (RSMST) approach recently introduced in the literature. The DOS's of GB's are compared against those of bulk materials as well as against one another. Although the RSMST calculations are still not self-consistent, these comparisons allow us to verify certain expected trends in the DOS's, and to verify the usefulness and reliability of our method.
High-Resolution Electron Microscopy of Olivine-Magnetite Interfaces
Authors: Mckernan Stuart , Carter C. Barry , Ricoult Daniel , Cullis A. G. 
Published: March 2011

ABSTRACTThe oxidation of iron-rich olivine to produce magnetite is a model system for the study of phase transitions involving mass transport. High-resolution lattice images of have been obtained from magnetite precipitates in naturally modified iron-rich olivines. The magnetite/olivine interface is shown to be extremely sharp. Steps and misfit dislocations are present at the interface.
Modeling of Nanophase Connectivity in Substance-Void Composite by Oblique Deposition
Authors: Motohiro T. , Noda S. , Isogai A. , Kamigaito O. 
Published: March 2011

ABSTRACTObliquely vapor deposited thin film is characterized by its unique inclined columnar structure. Recently one of the authors developed thin film optical quarter-wave plate by oblique deposition. SEM observation revealed the inclined columns of ∼10 nm in diameter and ∼3 microns in length. Its birefringence indicates those columns are less closely spaced in the plane of vapor incidence (PVI) than normal to PVI, composing alternatively stacked substance layer (columns laterally connected with each other)-void layer(residual space) nanophase composite with 2–2 connectivity. The growth mechanism of the inclined columnar structure has been successfully explained by the self-shadowing effect in 2D-space computer simulation in PVI. However, the connectivity development perpendicular to PVI is not self-evident. In the present work, we performed simple 3D-space simulation of oblique depositipon and observed substantial feature of the connectivity development and related features on this nanophase structure.
Atomic Structure and Chemistry of Si/Ge Interfaces Determined by Z-Contrast Stem
Authors: Chisholm M. F. , Pennycook S. J. , Jesson D. E. 
Published: March 2011

ABSTRACTThe technique of Z-contrast STEM provides a fundamentally new and powerful approach to determining the atomic scale structure and chemistry of interfaces. The images produced do not show contrast reversals with defocus or sample thickness, there are no Fresnel fringe effects at interfaces, and no contrast from within an amorphous phase. Such images are unambiguous and intuitively interpretable. In this paper, the technique has been used to directly image subnanometer interdiffusion in ultrathin (SimGen)p superlattices. The Z-contrast image of a (Si8Ge2)p superlattice grown by MBE at 400°C clearly shows significant broadening of the Gerich layer. Also, film formation and misfit accommodation in epitaxial Ge films on (001)Si produced by implantation and oxidation of Si wafers was studied. It was found that the Ge films, which are constrained to grow layer-by-layer, remain completely coherent with the Si substrate to a thickness of 5–6 nm. This is 3 to 6 times thicker than the observed critical thickness for Ge films grown on Si by MBE. It is observed that misfit accommodating dislocations nucleate at the film surface as Shockley partials. The Z-contrast images show these partials can combine to form perfect dislocations whose cores are found to lie entirely in the elastically softer Ge film.
Observation of Heteroepitaxially Grown Organic Ultrathin Layers on Inorganic Substrates by In Situ RHEED and by STM
Authors: Hara Masahiko , Sasabe Hiroyuki , Yamada Akira , Garito Anthony F. 
Published: March 2011

ABSTRACTAn organic molecular beam epitaxy (OMBE) system has been designed and constructed with in situ reflection high-energy electron diffraction (RHEED) specifically for the deposition of organic molefelar layers under ultrahigh vacuum (UHV), the order of 10–10 torr. The system is equipped with a portable UHV chamber which allows easy transfer of the OMBE film samples to a separate UHV scanning tunneling microscopy (STM) system. A structural investigation of heteroepitaxially grown organic ultrathin layers of copper phthalocyanine (CuPc) on inorganic substrates was carried out by the combined UHV system from less than a monolayer of CuPc.
Critical Thickness of GaAs/InGaAs and AlGaAs/GaAsP Quantum Wells Grown by Atmospheric Pressure OMCVD
Authors: Bertolet Daniel C. , Hsu Jung-Kuei , May Lau Kei , Koteles Emil S. 
Published: March 2011

AbstractA critical layer thickness study of strained GaAs/InGaAs and AlGaAs/GaAsP quantum wells (QWs) grown by atmospheric pressure organometallic chemical vapor deposition (OMCVD) is reported. Characterization by conventional photoluminescence (PL), photoluminescence excitation (PLE) spectroscopy, optical microscopy, and x-ray diffraction suggests that partial or regional relaxation begins to occur at critical thicknesses predicted by the force-balance model. To test the stability of strained quantum wells with well width near or exceeding the predicted critical thickness, annealing up to 850°C for ten minutes was carried out. No sign of degradation or complete relaxation of the QW layers was observed.
Electron Channeling Analysis of Elastic Strains in InGaAs Thin Films
Authors: Keller R. , Zielinski W. , Gerberich W.W. , Kozubowski J.A. 
Published: March 2011

AbstractInx Ga1-x As thin films were grown by MBE on (001) GaAs substrates. The associated 1% lattice mismatch resulted in the development of an elastic strain field in the systems. Electron channeling patterns (ECP) were then obtained from these samples in an SEM at different accelerating voltages, allowing data to be obtained over various information depths within the samples while keeping them intact. The ECPs showed sensitivity to the elastic strains both parallel and perpendicular to the film/substrate interface. Certain high order Laue zone (HOLZ) line positions showed good sensitivity to the Poisson strain in the films due to a rotation of atomic planes. These line positions varied with film thickness and distance from the interface. The technique shows promise as a tool for relatively easy elastic strain determination. Its limitations will also be discussed.
Microstructure of FCC/BCC Metal Multilayers
Authors: Jennett Nigel M. , Dingley D.J. , Ando Y. 
Published: March 2011

AbstractBilayers of Cu/Fe and Cu/V and multilayers of Ni/Fe have been grown under high vacuum and ultra high vacuum conditions respectively with [111] epitaxy. Multilayer layer thicknesses ranged from 3 monolayers to 15 monolayers per layer. Improved epitaxy of the UHV growth was, we believe, due to the better vacuum although perfect material could only be obtained for growth within a narrow and shifting substrate temperature ‘window’. Possible shortfall in the quality of the Cu backing layer epitaxy was averted by a 2hr anneal at 425°C.In the Fe/Ni multilayers the Fe was observed to adopt the FCC lattice rather than the equilibrium BCC lattice for layer thicknesses less than 10 monolayers. This change of structure coincided with a reduction in sample magnetic moment per volume attributed to a collapse of the Fe moment to a value 7 times less than bulk.