bluuebunny/crossref_metadata_2025_split huggingface dataset:
Influence of BHF Treatments on Hydrogen-Terminated Si(100)
Surfaces
Authors: Osada T. , Kawazawa Y. , Miyazaki S. , Hirose M. 
Published: April 2011

ABSTRACTThe hydrogen bonding features of Si(100) surfaces treated with BHF
(NH4F/HF/H2O) have been studied by Fourier
transform infrared attenuated total reflection spectroscopy (FT-IR-ATR). The
amount of residual silicon-fluorine bonds on Si(100) surfaces has been
evaluated by X-ray photoelectron spectroscopy (XPS). It is found that
Si-H3 bonds appears to be preferentially removed by OH ions so
as to increase the surface SiH2 and SiH bonds. On the other hand,
it is likely that fluorine-containing ionic species such as HF2
might attack the backbonds of surface hydrides to produce Si-H3
and Si-F bonds. ATR spectra have shown that a BHF treated Si(100) surface in
5∼10% NH4F with molar ratios of HF/NH4F=0.37∼0.56
(pH=3.7∼4.0) at a treatment time of 5 minutes is atomically flatter than
that treated in BHF containing 15∼20% NH4F. This is because the
amount of residual Si-F bonds on Si(100) increases with HF2
concentration in BHF and these Si-F bonds enhance attacking of silicon
backbonds of Si-F bond by OH− and HF2− ions.
The Effect of contamination solutions and substrate conditions
on Copper Particle Growth Behavior
Authors: Choi Geun-Min , Sekijne Katsuyuki , Morita Hiroshi , Ohmi Tadahiro 
Published: April 2011

ABSTRACTCu particle growth behavior on two silicon substrates, amorphous and single
crystal silicon, has been investigated using two contamination solutions.
This study reveals that the growth behavior of Cu particle depends on
substrate conditions and copper contamination solutions. Contamination level
is independent of split conditions. From the SEM images of an amorphous
silicon shows a big difference in the number of particles depending on
copper contamination solution. The amorphous silicon has similar native
oxide thickness in ultrapure water spiked with CuF2 and
CuCl2, whereas the single crystal silicon is different from
the native oxide thickness depending on copper contamination solution. When
1 ppm of Cu in ultrapure water was spiked as a function of time, the amount
of Cu impurity on amorphous silicon in the early dipping stage was measured
10 times higher than that on single crystal silicon for both of copper
contamination solutions.
The Adsorption-Desorption of Cations at the Silica-Water its
Implication in Wafer-Cleaning Efficacy
Authors: Lee W. , Torek K. J. , Palsulich D. A. , Weston L. 
Published: April 2011

ABSTRACTThe adsorption-desorption of various cations at the silica-water interface
is discussed in terms of electrical double layer and surface complexation
models. Some experimentally determined surface equilibria constants from the
literature are tabulated for Fe, Cu, and Mg. The adsorption phenomena of
those cations onto silica gel is described using the stability calculation
(STABCAL) computer program based on the suggested models.A chemical oxide (silica) is grown on the silicon surface during the SC1
and/or SC2 processes. Adsorption of Fe, Cu, and Mg onto this chemical oxide
is studied as a function of pH and compared to the modeling results. In
general, there is a qualitative correlation between the experimental and
modeling data, which can be used as a basis to develop a quantitative model
for cation adsorption-desorption on the wafer surface.
Transport Properties of Partially-Filled CeyCo4Sb12
Authors: Uher C. , Chen B. , Hu S. , Morelli D.T. , Meisner G.P. 
Published: April 2011

AbstractWe have investigated the magnetic and transport properties of CeyCo4Sb12 filled skutterudites with the filling fraction y ≤ 0.1. These compounds are n-type materials that develop a magnetic moment upon the presence of trivalent cerium. Cerium has a strong influence on all transport properties and even in small amounts it drastically reduces the lattice thermal conductivity. The resulting figures of merit are comparable to the values established previously for the p-type filled skutterudites.
Studies of Bulk Materials for Thermoelectric Cooling
Authors: Sharp Jeff W. , Nolas George S. , Volckmann Edward H. 
Published: April 2011

AbstractWe discuss ongoing work in three areas of thermoelectric materials research: 1) broad band semiconductors featuring anion networks, 2) filled skutterudites, and 3) polycrystalline Bi-Sb alloys. Key results include: a preliminary evaluation of a previously untested ternary semiconductor, KSnSb; the first reported data in which Sn is used as a charge compensator in filled antimonide skutterudites; the finding that Sn doping does not effect polycrystalline Bi1−xSbx as it does single crystal samples.
Progress on GaInAsSb And InAsSbP Photodetectors for MiD-Infrared Wavelengths
Authors: Shellenbarger Z. A. , Mauk M. G. , Sims P. E. , Cox J. A. , Lesko J. D. , Bower J. R. , South J. D. , Dinetta L. C. 
Published: April 2011

AbstractProgress on mid-infrared photodetectors fabricated by the liquid phase epitaxial growth of GaInAsSb, InAsSbP, and AlGaAsSb on GaSb and InAs substrates is reported. GaInAsSb p/n and p-i-n detectors, InAsSbP p/n detectors and AlGaAsSb/GaInAsSb avalanche photodiode (APD) structures were fabricated. Preliminary results indicate that these devices can have higher detectivity with lower cooling requirements than commercially available detectors in the same wavelength range. Infrared p/n junction detectors made from GaInAsSb and InAsSbP showed cut-off wavelengths of 2.3.μm and 2.8. μm respectively. Room temperature background noiselimited detectivity (D*BLIP) of 4 × 1010 cmHz1/2/W for GaInAsSb detectors and 4 × 108 cmHz1/2/W for InAsSbP was measured. Room-temperature avalanche multiplication gain of 20 was measured on AlGaAsSb/GaInAsSb avalanche photodiodes.
Free Carrier Absorption in P-Type Epitaxial Si and GaAs Films for far-Infrared Detection
Authors: Perera A. O. U. , Shen W. Z. , Tanner M. O. , Wang K. L. , Schaff W. 
Published: April 2011

AbstractWe report the investigation of free-carrier absorption characteristics for epitaxially grown p-type thin films in the far-infrared region (50 ∼ 200 μm), where homojunction interfacial workfunction internal photoemission (HIWIP) detectors are employed. Five Si and three GaAs thin films were grown by MBE over a range of carrier concentrations, and the experimental absorption data were compared with calculated results. The freehole absorption is found to be almost independent of the wavelength. A linear regression relationship between the absorption coefficient and the carrier concentration, in agreement with theory, has been obtained and employed to calculate the photon absorption probability in HIWIP detectors. The detector responsivity follows the quantum efficiency predicted by concentration dependence of the free carrier absorption coefficient.
Fabrication of Cdznte Strip Detectors for Large Area Arrays
Authors: Stahle C. M. , Shi Z. Q. , Hu K. , Barthelmy S. D. , Snodgrass S. J. , Lehtonen S. J. , Mach K. J. , Barbier L. , Gehrels N. , Krizmanic J. F. , Palmer D. , Parsons A. M. , Shu P. 
Published: April 2011

AbstractA CdZnTe strip detector large area array (∼ 60 cm2 with 36 detectors) with capabilities for high resolution imaging and spectroscopy has been built as a prototype for a space flight gamma ray burst instrument. The detector array also has applications in nuclear medical imaging. Two dimensional orthogonal strip detectors with 100 gm pitch have been fabricated and tested. Details for the array design, fabrication and evaluation of the detectors will be presented.
Tem Investigation of Al0.5Ga0.5As1-y Sby Buffer Layer Systems
Authors: Chen E. , Ahearn J. S. , Nichols K. , Uppal P. , Paine D. C. 
Published: April 2011

AbstractWe report on a TEM study of Sb-adjusted quaternary Al0.5Ga0.5As1-y Sby buffer-layers grown on <001> GaAs substrates. A series of structures were grown by MBE at 470°C that utilize a multilayer grading scheme in which the Sb content of Al0.5Ga0.5As1-ySby is successively increased in a series of eight 125 nm thick layers. Post growth analysis using conventional bright field and weak beam dark field imaging of these buffer layers in cross-section reveals that the interface misfit dislocations are primarily of the 60° type and are distributed through out the interfaces of the buffer layer. Plan view studies show that the threading dislocation density in the active regions of the structure (approximately 2 μm from the GaAs substrate) is 105–6/cm2 which is comparable to equivalent InxGa1−x As buffers. Weak Sb-As compositional modulations with a period of 1.8 nm were observed that provide a marker for establishing the planarity of the growth process. These features reveal that the growth surface remains planar through out the buffer layer growth sequence.
Control of Defects and Impurities in Production of CdZnTe Crystals by the Bridgman Method
Authors: Glass H. L. , Socha A. J. , Bakken D. W. , Speziale V. M. , Flint J. P. 
Published: April 2011

AbstractCadmium zinc telluride crystals were grown by vertical Bridgman processes using in situ compdunding from high purity elements into pyrolytic boron nitride crucibles within sealed fused quartz ampoules containing cadmium vapor at a pressure of roughly one atmosphere. These conditions produce material having the low etch pit density, low precipitate density, high infrared transmission and high purity required for use as substrates for infrared focal plane detector arrays fabricated in epitaxial mercury cadmium telluride. Similar processes should be satisfactory for producing cadmium zinc telluride for gamma ray detectors.
Photoresponse Studies of The Polarization Dependence of the CdGeAs2 Band Edge
Authors: Brown G. J. , Ohmer M. C. , Schunemann P. G. 
Published: April 2011

AbstractMid-infrared photoresponse studies were performed on an oriented p-type cadmium germanium arsenide uniaxial crystal. The effects of optical polarization alignment, parallel and perpendicular to the c-axis of the crystal, were studied, as well as the effects of the transport electric-field direction. The measured optical band edge was 0.578 eV at 10 K for all polarization and bias configurations. This band gap energy is in good agreement with absorption and photoluminescence results for this sample. However, the photoresponse spectrum measured with unpolarized light at 10 K showed a much lower onset at 0.50 eV. This difference in the low temperature activation energy of the photoresponse is attributed to deep native defect levels near the band edge. These deep levels at times obscure the true band edge and can cause under estimates of the band gap energy. These results can explain the wide disparity in the reported CdGeAs2 band gap in the literature. In addition, the intensity of the photoresponse was found to be only slightly dependent on the optical polarization direction, but strongly dependent on the bias electric-field direction. The largest photoreponse was observed when the optical polarization was parallel to the c-axis and the bias electric field was perpendicular to the c-axis. The bias electric-field direction also had a significant effect upon the temperature dependence of the peak photoresponse intensity. The temperature dependence of the CdGeAs2 energy band gap was determined by empirical fitting.
Influence of Quantum Confinement on the Photoemission From Nonlinear Optical Materials
Authors: Ghatak Amakhya P. , Bose P. K. , Majumder Gautam 
Published: April 2011

Abstractwells (QWs), quantum well wires (QWWs) and quantum dots (QDs) of nonlinear optical materials, respectively on the basis of a newly derived electron dispersion law considering all types of anisotropies within the framework of k.p. formalism. It is found, taking CdGeAs2, GaAs and InAs, as exmaples, that the photoemission increase with increasing photon energy in a ladder like manner and also exhibits oscillatory dependences with changing electron concentration with film thickness respectively for all types of quantum confinement. The photoemission current density is greatest in QDs and least in QWWs. In addition, the theoretical results are in agreement with the experimental observation as reported elsewhere.
Theoretical Performance Of Mid-Infrared Broken-Gap Multilayer Superlattice Lasers
Authors: Flatté Michael E. , Olesberg J. T. , Grein C. H. 
Published: April 2011

AbstractWe present calculations of the intersubband absorption and Auger recombination rate of superlattices based on the InAs/GaInSb material system involving more than two layers in the repeating unit cell and strain balanced to match the GaSb substrate. We demonstrate theoretically the presence of final-state optimization in a 4.0 μm strain-balanced brokengap superlattice. This system's band structure is optimized not only at the band edge, where the valence density of states has been reduced, but also at resonance energies, where reside final states for Auger and intersubband processes. The spectral structure of the intersubband absorption, which for some wavelengths near the lasing wavelength can exceed 500 cm−1 at lasing threshold, has been considered when designing this active region. Fortunately, final-state optimized designs which minimize Auger recombination tend to minimize intersubband absorption as well. The effectiveness of final-state optimization is evaluated by considering band structures with identical band edge structure, but different final-state structure.
Evaluation of Indium Diffused M-i-n CdZnTe Detectors
Authors: Gagliardi M-A. , Nenonen S. , Gagliardi T. , Aleksejeva L. , Ivanov V. , Bavdaz M. 
Published: April 2011

AbstractOne of the main electronic noise sources of a room temperature spectroscopy system is the leakage current of a detector. It can be reduced with a pn-junction type detector structure such as a M-i-n configuration, and with cooling. In this work eight CdZnTe detectors with a M-i-n structure were fabricated by indium diffusion. The junction was characterized by a currentvoltage technique. Detector electrical, charge collection and spectroscopic properties were compared to the ones received with the traditional electroless Au contacts, before the junction formation. As a result of the indium diffusion an improved detector leakage current performance was achieved. However, a corresponding improvement in the detector energy resolution was not always observed due to the CdZnTe charge collection properties and process variables.
Spectroscopic Response Versus Interelectrodic Charge Formation Position in CdTe Detectors
Authors: Auricchio N. , Caroli E. , Cesare G. De , Dusi W. , Grassi D. , Hage-Ali M. , Perillo E. , Siffert P. , Spadaccini G. 
Published: April 2011

AbstractThe electron-hole pair production energy (∼ 4.43 eV) in cadmium telluride semiconductor based detector would allow, in principle, to achieve spectroscopic performance close to germanium. In fact the material impurities, crystal lattice defects and low charge mobility, mainly for holes, can severely degrade the spectroscopic properties through charge trapping/detrapping and recombination phenomena, limiting the usable distance between the electrodes. The charge collection efficiency depends, following the Hecht relation, on the distance between the charge production location and the collecting cathode; we have studied the dependence of some CdTe spectroscopic parameters (energy resolution, photo-peak gain and efficiency) from this distance. A set of experimental tests were performed using a well collimated photon beam. The beam spot, obtained from a 57Co radioactive source through a thick (20 mm) tungsten collimator having a 0.2×2 mm window, was positioned between the two electrodes of a CdTe crystal of size 3×5×2 mm3, with the electrodes deposited on the 3×5 mm2 sides.The detector was irradiated on the face having the area of 2×3 mm2, in the arrangement with the collecting field orthogonal to the incoming radiation (PTF configuration), and the largest side of the spot parallel to the electrode plane. Using a micro-positioning system a fine scanning of the interelectrodic region was performed.In order to evaluate the detector behavior in a wider energy range, further tests using energies between 14 keV to 662 keV have been performed.The results of these measurements are presented and discussed in order to emphasize a method to improve CdTe detector spectroscopic capabilities and to understand the detection behavior
Raman And Photo-Luminescence Studies On Intrinsic And Cr-Doped Znse Single Crystals
Authors: Rai Brajesh K. , Bhaskar S. , Bist H. D. , Katiyar R. S. , Chen K.-T. , Burger A. 
Published: April 2011

AbstractSingle crystals of ZnSe, with varying amounts of Cr doping have been studied using Raman and photoluminescence(PL) spectroscopy. The Cr-doped samples show the existence of a coupling mechanism of longitudinal optical(LO) phonons of ZnSe with hole-plasmons. The dependence of intensity ratio of LO and transverse optical(TO) mode on temperature and excitation wavelength, has been attributed to the interaction of the field of LO phonons with the surface electric field in the depletion layer. The interaction of discreet phonons with the electronic continuum of conduction band in ZnSe is responsible for the shift of Raman peaks. The large electron capture cross-section of deep-level Cr2+ and Cr1+ impurities is inhibitive for the observation of band-to-band PL transition at ˜2.7eV in ZnSe:Cr.
Dielectric Spectroscopy Study Of Znse Grown By Physical Vapor Transport
Authors: Kokan Julie , Gerhardt Rosario , Su Ching-Hua 
Published: April 2011

AbstractZnSe, although generally thought of as a wide band gap semiconductor, is insulating in the as-grown state. It is only after heat treatment in a zinc rich atmosphere that semiconducting properties are observed Therefore, dielectric spectroscopy is an appropriate tool to study the electrical properties of as grown ZnSe. The dielectric properties of large-grained samples of ZnSe grown by physical vapor transport were measured as a function of frequency. Differences can be seen in the dielectric properties of samples grown under different conditions (such as the effect of a seed and the orientation of the gravity field during growth). The spectra of heat treated samples were also acquired and were found to exhibit significant deviations from those of the as grown crystals.
Polymer Layer Ordering of Polyaniline Derivatives in Pled Devices: Surface Adsorption and Characterization
Authors: Advincula R. C. , Knoll W. , Frank C. W. , Roitman D. , Moon R. , Sheats J. 
Published: April 2011

AbstractThe fabrication and characterization of polyaniline (PANI) derivatives deposited on ITO coated glass is investigated as possible hole injection layers for MEH-PPV based polymer light emitting diode (PLED) devices. This involved multilayer ordering by the alternate polyelectrolyte adsorption of polyaniline and sulfonated poyaniline with an oppositely charged polyelectrolyte from solution. A combination of spectroscopic and microscopic techniques was utilized to determine the layer ordering, film structure, morphology, and homogeneity. The deposition process generally showed a linear behavior for all pairs as shown by ellipsometry and UV-vis spectroscopy. However, surface plasmon spectroscopy (SPS) and AFM revealed that thicker films are accompanied by increased surface roughness regardless of concentration. Comparison in performance was made between bare ITO and PANI or SPANI coated devices. Initial investigations of PLED performance showed significant improvements in lifetime and efficiency compared to bare ITO.
Photofabrication of Surface Relief Gratings using Post Functionalized Azo Polymers
Authors: Tripathy Sukant K. , Kumar Jayant , Kim Dong-Yu , Jiang Xinli , Wang Xiaogong , Li Lian , Sukwattanasinitt Mongkol , Sandman Daniel J. 
Published: April 2011

AbstractA series of azobenzene functionalized polymers has been synthesized by post polymerization azo coupling reaction. Photo-fabrication of surface relief gratings were studied on the polymer films. Epoxy based azo polymers were prepared by post azo coupling reaction to form polymers containing donor-acceptor type azo chromophores. The azo chromophores were designed to contain ionizable groups to impart self-assembling and photoprocessing capabilities to the polymers. The polymers containing 4-(4-(carboxylic acid)phenylazo)aniline chromophores can be directly photofabricated to form surface relief gratings with large surface modulations. Charge interactions had a strong influence on the details of the writing process. A new soluble polydiacetylene, post-functionalized with azobenzene groups was also prepared. Large amplitude surface gratings could be fabricated on this polydiacetylene film as well.
Molecular Second-Order Optical Nonlinearity of Push-Pull Bisdithiolene Nickel Complexes
Authors: Chen Chin-Ti , Liao Sish-Yuan , Lin Kuan-Jiuh , Lai Long-Li 
Published: April 2011

AbstractThe synthesis and characterization of donor-acceptor substituted unsymmetrical bisdithiolene nickel complexes are described for the first time. X-ray single crystal data indicate that the complexes exist with two types of bonding structures, namely, the π-localized and π-delocalized structures. The relation between bonding structures and the molecular second-order nonlinear optical properties, i.e., solvatochromism, dipole moment, and molecular first hyperpolarizability is discussed.
New Photopolymers Based on Two-Photon Absorbing Chromophores and Application to Three-Dimensional Microfabrication and Optical Storage
Authors: Cumpston B. H. , Ehrlich J. E. , Erskin L. L. , Heikalt A. A. , Hu Z.-Y. , Leet I.-Y. S. , Levin M. D. , Marder S. R. , McCord D. J. , Perry J. W. , Röckel H. , Rumi M. , Wu X.-L. 
Published: April 2011

AbstractMolecules exhibiting strong two-photon absorption hold great potential for a wide range of applications including two-photon fluorescence imaging, three-dimensional (3D) optical data storage, and 3D microfabrication. We have observed two-photon absorptivities as high as 1500×10− 50 cm4 s/photon in bis-donor diphenylpolyene derivatives that are correlated to simultaneous charge transfer from the end groups to the polyene bridge in the molecule. Many of these molecules are also excellent photoexcitable electron donors that can initiate charge-transfer reactions with acrylate monomers. Marcus theory is used to describe the efficiency of these charge-transfer reactions. Polymerization rates have also been measured and we show that these twophoton chromophores display increased sensitivity and recording speed over conventional UV photo-initiators. The fabrication of complex, three-dimensional structures by twophoton polymerization is demonstrated and discussed in the context of advanced photonic applications.
Design and Synthesis of New Conjugated Porphyrin Copolymers for Optical-Electronic Applications
Authors: Jiang Biwang , Yang Szu-Wei , Lam Phuong T. , Jones Wayne E. 
Published: April 2011

AbstractNew linear conjugated porphyrin polymers were synthesized by a palladium-catalyzed cross-coupling reaction of [5,15-bis(ethynyl)-10,20-bis (mesityl)porphyrin]zinc and diiodobenzene derivatives. Enhanced solubility of the conjugated porphyrin polymers was achieved by attachment of long alkyl ether or dialkyl amide groups to the aryl moiety, resulting in unambiguous characterization by 1H NMRLR, GPC, UV-Vis and fluorescence spectroscopies. The introduction of alkyl ether (electron donor) or dialkyl amide (electron acceptor) results in significant modulation of the electronic properties of the conjugated porphyrin polymers due to strong electronic coupling. The spectroscopic and electronic characterization of these materials provides for comparison to earlier preparations of ethynyl bridged conjugated copolymers in which electronic coupling was substantially weaker.