bluuebunny/crossref_metadata_2025_split huggingface dataset:
High Resolution X-Ray Reciprocal Space Mapping of Wavy Layers
Authors: Kidd P. , Fewster P. F. 
Published: April 2011

ABSTRACTWe apply the technique of High Resolution X-ray Reciprocal Space Mapping (HRRSM) to the study of wavy layers in InGaAs multilayer thin films on InP substrates. By accurately measuring the positions of the layer Bragg peaks in reciprocal space we obtain measurements of the compositions and residual coherency strains in the layers. We discuss the contributions to the diffuse scatter around the Bragg peaks from factors such as lattice tilts and interface roughness. By modelling the shapes of the diffraction profiles we obtain measurements of mosaic block size both perpendicular and parallel to the multilayer/substrate interface. We conclude that the wavy interface morphology arises predominantly from layer thickness variations rather than lattice tilts.
Orientation Characteristics with Process Parameters of PLZT(X/70/100) Thin Films Prepared by RF-Magnetron Sputtering
Authors: Kang S.K. , Park M.S. , Kim D.B. , No K.S. , Cho S.H. 
Published: April 2011

ABSTRACTPLZT(X/70/100) thin films on MgO(100), Pt/Ti/MgO(100), and Pt/Ti/Si(100) have been prepared by RF-magnetron sputtering process from sintered target with compositions of PLZT(X/70/100), where X=5, 10, and 15, respectively. The effects of substrate temperature, substrate and gas pressure on deposited thin films were studied. Crystalline and surface characterization was analyzed using XRD, SEM, AES, and AFM. X-ray rocking curves were measured to examine the film orientation. It was observed that the gas pressure was the dominant influence on having (001) preferred orientation. As a result, the degree of c-axis orientation increased as gas pressure decreased.
Low-Temperature (450 °C) Poly-Si Thin Film Deposition on SiO2 and Glass using a Microcrystalline-Si Seed Layer
Authors: Wolfe D. M. , Wang F. , Lucovsky G. 
Published: April 2011

ABSTRACTA low-temperature (450 °C), remote plasma-assisted CVD process for deposition of poly-Si thin films on SiO2 and Corning 7059 glass in which interface formation is separated from bulk film growth has been developed. This approach is based on first depositing an ultra-thin (<100 Å) microcrystalline-Si seed layer onto the oxide in order to provide nucleation sites at which low-temperature poly-Si film growth can be initiated. Conditions for poly-Si film deposition were optimized by using a low-temperature, remote plasma process that had previously yielded epitaxial growth of Si thin films on crystalline Si substrates. Microstructural characterization was performed on poly-Si films grown with different seed layer thicknesses, and additionally with exposure of this seed layer to a predeposition hydrogen plasma treatment. Results demonstrated that the seed layer thickness and surface morphology played a significant role in promoting crystallinity in the poly-Si overlayer. For example using deposition conditions that yielded epitaxial film growth on Si substrates, films deposited on un-seeded oxide substrates were amorphous, whereas those deposited using a seed layer were polycrystalline. This indicated that interfacial nucleation was the rate limiting step in promoting the low-temperature deposition of poly-Si thin films.
A Low Temperature Polycrystalline Si TFT Technology for Large area AMLCD Drivers
Authors: Saraswat Krishna C. , Subramanian V. , Jurichich S. 
Published: April 2011

ABSTRACTIn this paper we describe a low thermal budget technology to fabricate high performance CMOS thin-film transistors (TFTs) in polycrystalline silicon and silicon/germanium on low cost glass substrates, for active-matrix liquid crystal display (AMLCD) applications. Based on modeling of delay times of the scan and data lines driven by n-channel TFTs we show that for AMLCDs with integrated drive circuits, mobility in excess of 40 cm2/V. sec will be required. Through proper optimization of amorphous film deposition, crystallization (nucleation and grain growth), fabrication process parameters and device structure we have obtained mobility in excess of 50 cm2/V. sec in Si TFTs, using conventional manufacturing technology compatible with glass substrates. Economic modeling suggests that low-temperature poly-TFT LCDs with integrated drivers will have a competitive manufacturing cost to LCDs of an equivalent size and resolution with α-Si pixel TFTs and single crystal drivers.
Planarization of Gratings using Magnetorheological Finishing
Authors: Yang Fuqian , Golini D. , Raguin D. H. , Jacobs S. D. 
Published: April 2011

ABSTRACTSurface planarization of BK7 glass gratings with periods of 130, 30, 16, 8 and 5 gm was performed with the magnetorheological finishing (MRF) process at the Center for Optics Manufacturing (COM). Approximately 0.5 μm of material was removed in the experiments. Grating height decreased as a function of grating period, going from ∼0.44 μm to ∼0.044 μm for a 130 μm period, and ∼0.44 μm to ∼30 Å for grating periods of 30, 16, 8 and 5 gm. The microroughness on ridges and in valleys of the grating structures also decreased with material removal from ∼100 Å to ∼10 Å for gratings with 30 and 16 μm periods.
Low pH Chemical Etch Route for Smooth H-Terminated Si(100) And
Study Of Subsequent Chemical Stability
Authors: Hinds B. J. , Aspnes D. E. , Lucovsky G. 
Published: April 2011

ABSTRACTTo form atomically flat H-passivated Si(100) surfaces, wet chemical etching
of sacrificial SiO2 layer has been examined. Roughness and
chemical overlayer thickness, as monitored by ellipsometry shows a minima at
an optimal solution of 1:0.5:30 HF(49wt\%):H2SO4
(98wt\%):H2O. A mechanistic study offers no evidence for a
chemical smoothing from preferential non-Si(100) facet etching. Silicon
planarization can be induced by rapid thermal annealing RTA of chemical
oxides. The H-terminated Si(100) surfaces are found to be moderately
reactive to ambient conditions as monitored by in-situ ellipsometry and
Auger analysis. Atomic force microscopy (AFM) measurements show Si(100)
surfaces to have a rms ∼1.0Å and Rmax values of 1.6–0.9Å. With
measured roughness incorporate into ellipsometric model, a 5Å native oxide
overlayer is rapidly incorporated into the Si(100) surface.
Lifetime Characterization of Poly-Silicon Back Sealed Wafers
with Bi-Surface Photoconductivity Decay Method
Authors: Ogita Y. , Uematsu Y. , Daio H. 
Published: April 2011

ABSTRACTBi-surface photoconductivity decay (BSPCD) method has been useful to obtain
the true bulk lifetime and surface recombination velocities in silicon
wafers with variously finished surfaces. Thermally oxidized n-type CZ
silicon wafers with and without a poly-Si back seal (PBS) were characterized
with the BSPCD method using 500 MHz-UHF wave reflection. It has been found
that the surface recombination velocity of the PBS surface is, 4027 cm/s
while that of the no-PBS surface is 16 cm/s, for example. The very fast
surface recombination velocity is attributed to the poly-Si / Si interface
character. Moreover, the bulk lifetime calculated in the PBS wafer is much
higher than that in the no-PBS one, which reveals the PBS gettering
performance for the thermal oxidation induced contamination.
Growth Chemistry of Ultrathin Silicon Nitride and Oxynitride
Passivation Layers on Si(100)
Authors: Kamath A. , Kim B. Y. , Blass P. M. , Sun Y. M. , White J. M. , Kwong D. L. 
Published: April 2011

ABSTRACTWe have studied the thermal growth chemistry and bonding structure of three
promising ultrathin (5–20Å), nitrogen rich passivation layers on Si(100),
namely-Si3N4, NO/Si(100) grown oxynitride and NO
annealed SiO2. These films are intended to serve as substrates
with excellent diffusion barrier/interface properties during deposition of
high- K dielectrics such as Ta2O5, with
tSiO2 equivalent <30Å for ULSI applications. In this paper
we show that it is possible to form films with a tailored composition and
nitrogen profile using techniques that can easily be integrated with
existing silicon processing technology. Alternating growth and surface
analysis by X-Ray Photoelectron Spectroscopy (XPS) is used to non
destructively characterize the growth.
Effect of Cl in Gate Oxidation
Authors: Mertens P. W. , McGeary M. J. , Schaekers M. , Sprey H. , Vermeire B. , Depas M. , Meuris M. , Heyns M. M. 
Published: April 2011

ABSTRACTThe present study reviews the use of Cl in gate oxidation furnaces for growth of high quality gate oxides with a thickness in the range of 2 to 15 1nm. The following, commercially available, “state of the art” Cl-precursors have been tested: 1,1,1- trichloroethane (TCA),trans-1,2-dichloroethylene (DCE) and oxalyl chloride (OC). Different parameters were evaluated including: metal removal efficiency, poly-silicon haze, Fe bulk incorporation, carrier lifetime and Cl-incorporation in the oxide. Cl2was identified as the active component in Cl-oxidation. As a consequence, OC was identified as being the most efficient Cl-source. In particular, OC is the most suited Cl-source for applications requiring reduced oxygen concentration, such as the manufacturing of ultra thin gate oxides.
Thermoelectric Properties of N-Type Bi2(Tel−xSex)3 Fabricated by Mechanical Alloying and Hot Pressing
Authors: Kim Hee-Jeong , Choi Jae-Shik , Oh Tae-Sung , Hyun Dow-Bin 
Published: April 2011

AbstractThermoelectric properties of polycrystalline Bi2(Te1−xSex)3 (0.05 ≤ x ≤ 0.25), fabricated by mechanical alloying and hot pressing, have been investigated. Formation of n-type Bi2(Te0.9 Se0.1)3 alloy powders was completed by mechanical alloying for 3 hours at ball-to-material ratio of 5: 1, and processing time for Bi2(Te1−xSex)3 formation increased with Bi2Se3 content x. Figure-of-merit of Bi2(Te0.9Se0.1) was markedly increased by hot pressing at temperatures above 450°C, and maximum value of 1.9 × 10−3/K was obtained by hot pressing at 550°C. With addition of 0.015 wt% Bi as acceptor dopant, figure-of-merit of Bi2 (Te0.9Se0.1)3, hot pressed at 550°C, could be improved to 2.1 × 10−3/K. When Bi2(Te1−xSex)3 was hot pressed at 550°C, figure-of-merit increased from 1.14 × 103/K to 1.92 × 10−3/K with increasing Bi2Se3 content x from 0.05 to 0.15, and then decreased to 1.30 × 103/K for x = 0.25 composition.
Filled Skutterudite Antimonides: Validation of the Electron-Crystal Phonon-Glass Approach to New Thermoelectric Materials
Authors: Mandrus D. , Sales B. C. , Keppens V. , Chakoumakos B. C. , Dai P. , Boatner L. A. , Williams R. K. , Thompson J. R. , Darling T. W. , Migliori A. , Maple M. B. , Gajewski D. A. , Freeman E. J. 
Published: April 2011

AbstractAfter a brief review of the transport and thermoelectric properties of filled skutterudite antimonides, we present resonant ultrasound, specific heat, and inelastic neutron scattering results that establish the existence of two low-energy vibrational modes in the filled skutterudite LaFe3CoSb12. It is likely that at least one of these modes represents the localized, incoherent vibrations of the La ion in an oversized atomic “cage.” These results support the usefulness of weakly bound, “rattling” ions for the improvement of thermoelectric performance.
Properties Of Cosb3 Films Grown by Pulsed Laser Deposition
Authors: Christen Hans-Martin , Mandrus David G. , Norton David P. , Boatner Lynn A. , Sales Brian C. 
Published: April 2011

AbstractPolycrystalline CoSb3 films were grown on a variety of electrically insulating substrates by pulsed laser ablation from a stoichiometric hot-pressed target. These films are fully crystallized in the skutterudite structure, and the grains exhibit a strongly preferred alignment of the cubic [310]-axis perpendicular to the substrate surface. The film quality is studied for different single-crystal substrates and as a function of growth temperature and background gas.Hall measurements show that the films are p-type semiconducting with a room-temperature carrier density of 3×1020 holes/cm3. The Hall mobility is found to be 50 to 60 cm2 /Vs, which is high for such a heavily-doped material. The Seebeck coefficient and the resistivity are measured as a function of temperature and are compared to bulk measurements.
Influence of Structural Defects and Zinc Composition Variation on the Device Response of Cd1−xZnxTe Radiation Detectors
Authors: Yoon H. , Scyoc J. M. Van , Gilbert T. S. , Goorsky M. S. , Brunett B. A. , Lundt J. C. , Hermon H. , Schieber M. , James R. B. 
Published: April 2011

AbstractZinc composition variation and gross structural defects including grain and tilt boundaries, twins, and mechanical cracks in high pressure Bridgman Cd1−xZnxTe are characterized and correlated to various detector-related responses. Triple axis x-ray diffraction, double crystal x-ray topography, infrared microscopy, and etch pit density measurements are used to reveal and quantify the spatial distribution and the nature of the structural defects. Mechanical cracks in the material are found to act as conductive “shorting paths”, indicated by excessive leakage currents and reduced charge (electron) collection measured along these cracks. Reduced charge collection is also obtained across grain boundaries and in regions with poor crystallinity, indicating that they serve as carrier recombination sites. Finally, the effects of the zinc composition variation on the measured leakage current and the amount of electrons collected are found to be masked by gross structural defects. These characterization techniques provide a wealth of information which can be used not only to study the relationship between the structural and device properties of CdZnTe but also to screen production material for subsequent device fabrication.
Performance of P-I-N CdZnTe Radiation Detectors and Their Unique Advantages
Authors: Sudharsanan R. , Stenstrom C. C. , Bennett P. , Vakerlis G. D. 
Published: April 2011

AbstractWe present the performance characteristics of CdZnTe radiation detectors with a new P-I-N design and their unique advantages over metal-semiconductor-metal (M-S-M) devices. In M-S-M CdZnTe detectors the bulk resistivity of the substrate largely determines the leakage current. High leakage current is a dominant noise factor for CdZnTe detector arrays, coplanar detectors, and detectors used for low X-ray energy applications. P-I-N devices provide low leakage currents. Early CdZnTe detectors exhibited polarization, were limited to small detection volumes, and some required high deposition temperatures. We have developed a new heterojunction design which can be deposited at low temperatures so that even high-pressure Bridgman CdZnTe can be used. Using the P-I-N design, CdZnTe detectors with high detection volumes (>200 mm3) were fabricated and exhibited low leakage current, good energy resolution, and no polarization. These detectors have significant advantages over M-S-M detectors in three specific areas. First, X-ray fluorescence studies require detectors with low leakage currents to provide less spectral broadening due to electronic noise. Second, less expensive vertical Bridgman CdZnTe material can be used for imaging applications since it normally possesses too low of a bulk resistivity to be useful as a M-S-M detector. Third, leakage currents across the anode grid in large volume coplanar detectors can be significantly reduced.
X-ray Characterization of PbTe/SnTe Superlattices
Authors: Ferreira S. O. , Abramof E. , Rappl P. H. O. , Ueta A. Y. , Closs H. , Boschetti C. , Motisuke P. , Bandeira I. N. 
Published: April 2011

AbstractPbTe/SnTe superlattices have been proposed many years ago for use as base material for infrared detectors. However, many difficulties have prevented its use, mainly the ones related to obtaining low concentration SnTe. Recently we have shown that SnTe layers with relatively low hole concentration can be grown by molecular beam epitaxy at low temperature using stoichiometric charges. In this work we investigate the structural properties of PbTe/SnTe superlattices grown by molecular beam epitaxy on (111) BaF2 substrates. Sample characterization has been done by high resolution x-ray diffraction. Information on strain was obtained from reciprocal space maps of asymmetric Bragg reflections and used as input parameters for dynamical simulation of the diffraction spectra.
Bridgman Growth and Characterization of Bulk Single Crystals of Ga1−xInxSb for Thermophotovoltaic Applications
Authors: Boyer J. R. , Haines W. T. 
Published: April 2011

AbstractThermophotovoltaic generation of electricity is attracting renewed attention due to recent advances in low bandgap (0.5–0.7 eV) III-V semiconductors. The use of mixed pseudo-binary compounds allows for the tailoring of the lattice parameter and the bandgap of the material. Conventional deposition techniques (i.e., epitaxy) for producing such ternary or quaternary materials are typically slow and expensive. Production of bulk single crystals of ternary materials, for example Gal-xlnxSb, is expected to dramatically reduce such material costs. Bulk single crystals of Ga1−xInxSb have been prepared using a Bridgman technique in a two-zone furnace. These crystals are 19 mm in diameter by approximately 50 mm long and were produced using seeds of the same diameter. The effects of growth rate and starting materials on the composition and quality of these crystals will be discussed and compared with other attempts to produce single crystals of this material.
Thermal Interdiffusion in InGaAs/GaAs Strained Multiple Quantum Well Infrared Photodetector
Authors: Lee Alex S. W. , Li E. Herbert , Karunasiri Gamani 
Published: April 2011

AbstractRTA at 850 °C for 5 and 10 s is carried out to study the effect of interdiffusion on the optical and electrical properties of strained InGaAs/GaAs quantum well infrared photodetector. Photoluminescence measurement at 4.5 K shows that no strain relaxation or misfit dislocation formation occurs throughout the annealing process. Absorption and responsivity peak wavelengths are red shifted continuously without appreciable degradation in absorption strength. The normal incident absorption, which is believed to be the result of band-mixing effects induced by the coupling between the conduction and valence and is usually forbidden in conventional polarization selection rule, is preserved after interdiffusion. Responsivity spectra of both 0° and 90° polarization are of compatible amplitude and the shape of the annealed spectra becomes narrower. Dark current of the annealed devices is not very sensitive to temperature variation and is found to be an order of magnitude larger than the as-grown one at 77K.
Phase-matched 2nd harmonic generation in asymmetric doublequantum wells
Authors: Vodopyanov K. L. , Phillips C. C. , Vurgaftman I. , Meyer J. R. 
Published: April 2011

AbstractPhase-matched SHG, resonantly enhanced near λ=8.6μm, with ∼1% efficiency and up to 30 W peak power has been observed in asymmetric double multi-quantum well structures. Waveguide-mode and 45° wedge multi-bounce geometries were used.
Growth of NLO Chalcopyrite Materials by Omvpe
Authors: Timmons M. L. , Bachmann K. J. 
Published: April 2011

AbstractThis paper describes the application of organometallic vapor phase epitaxy to the growth of II-1V-V2 chalcopyrite materials that have high figures of merit for nonlinear optical (NLO) applications. ZnGeAs2, although not a particularly interesting NLO material, is used as a model for the growth of ZnGeP2, which is. Both compounds, as well as others, have been successfully grown by vapor phase on III-V substrates that provide a close lattice match. Doping studies using Group II and VI elements have been undertaken to control the p-type conductivity found in both compounds. Except for the possible case of indium, the results of these experiments are less than encouraging. Minority-carrier lifetimes of 150 ns have been measured in ZnGeAs2.The results of this work are used to make projections about the growth of CdGeAs2. CdGeAs2 is promising for the next generation of NLO mid-infrared materials if an absorption band that occurs at about 5 μm can be reduced. The growth projections suggest that this compound will be difficult to grow epitaxially and has no III-V substrate that provides a close lattice match. Mixing CdGeAs2 with other II-IV-V2 materials may offer solutions to the substrate problem. The defect properties of CdGeAs2 have not, to our knowledge, been studied.
Refractive Index Measurements of Barium Titanate From .4 to 5.0 Microns and Implications for Periodically Poled Frequency Conversion Devices
Authors: Zelmon David E. , Small David L. , Schunemann Peter 
Published: April 2011

AbstractBarium titanate has recently been suggested as a possible candidate for use in periodically poled optical frequency conversion devices. We report refractive index measurements which are critical to periodically poled device designers and present quasi phase matching loci which can be used to design an optical parametric oscillator in periodically poled barium titanate
Photoreflectance Study of MBE Grown Te-doped GaSb at the E0+Δ0 Transition
Authors: Iyer S. , Mulugeta S. , Li J. , Mangalam B. , Venkatraman S. , Bajaj K. K. 
Published: April 2011

AbstractPhotoreflectance (PR) measurements have been performed on MBE grown GaSb samples at the E0+Δ0 transition. The transition energy has been measured from 4 to 300 K in the 1.35 to 1.8 eV energy region. Transition energy of 1.614 eV and broadening of 53 meV have been obtained at 4 K from a representative Te-doped sample while no PR signals were obtained from undoped samples. The logarithmic dependence of the PR amplitude and invariance of the line shape on the modulating pump intensity, and absence of Franz-Keldysh oscillations are typical of the PR spectra in the low-field regime. Good fits were obtained using line shape analysis of the PR spectra and the temperature dependence of the transition energy and broadening have been determined.
Oxygen-Related Defects in In0.5(AlxGa1−x)0.5P Grown by MOVPE
Authors: Cederberg J. G. , Bieg B. , Huang J.-W. , Stockman S. A. , Peanasky M. J. , Kuech T. F. 
Published: April 2011

AbstractOxygen related defects in Al-containing semiconductors have been determined to degrade luminescence efficiency and reduce free carrier lifetime, affecting the performance of light emitting diodes and laser diodes. We have used the oxygen doping source, diethylaluminum ethoxide, (C2H5)2A1OC2H5, to intentionally incorporate oxygen-related defects during growth of In0.5(AlxGa1−x)0.5P by Metalorganic Vapor Phase Epitaxy (MOVPE). Our investigations have identified several defects which are ‘intrinsic’ or present in non-intentionally oxygen-doped n-type In0.5(AlxGa1−x)0.5P as well as those due to oxygen, which introduces defect states near the middle of the conduction band. Deep level transient spectroscopy and photoluminescence data obtained for these defects over a range of composition, are presented illustrating the trends in defect structure with alloy composition. The impact of oxygen contamination on the visible emission spectrum is presented and discussed in terms of the defect structure.
MID-IR Vertical Cavity Surface-Emitting Lasers
Authors: Vurgaftman I. , Bewley W. W. , Felix C. L. , Aifer E. H. , Meyer J. R. , Goldberg L. , Chow D. H. , Selvig E. 
Published: April 2011

AbstractAn optically pumped mid-infrared vertical-cavity surface-emitting laser based on an active region with a “W” configuration of type-II antimonide quantum wells is reported. The emission wavelength of 2.9 ym has a weak temperature variation (dλ/dT ≈ 0.07 – 0.09 nm/K), and the multimode linewidth is quite narrow (2.5–4 nm). Lasing is observed up to T = 280 K in pulsed mode and up to 160 K cw. Under cw excitation at T = 78 K, the threshold pump power is as low as 4 mW for a 6 am spot, and the differential power conversion efficiency is 4.5%.