bluuebunny/crossref_metadata_2025_split huggingface dataset:
Developing a Method for Wide-Control of the Self-Bias and its Adoption to Ion-Damage Control
Authors: Ohte Takeo , Goto Makoto , Sugawara Minoru 
Published: March 2011

AbstractWe have developed a technique which enables us to reduce the self-bias voltage without introducing any substantial disturbance to the main plasma. This approach is based on decreasing the floating potential of the powered electrode by means of injecting an electron current from the electrode. Instead of employing a hot cathode, we have used an auxiliary glow discharge to supply the electron emission. The controllable range of the self-bias has been extended to almost 0 V. A theoretical explanation of the variation of the floating potential with the emission current has been carried out. Measurements of the floating voltage(Vf) are plotted against ln(1/Iau), where Iau is the auxiliary discharge current. A good linear relationship of Vf vs. ln(1/Iau) is obtained as expected from the theory, and its slope gives the electron temperature.In order to appraise the degree of damage induced by the bombardment of ions accelerated by the sheath voltage, we have estimated the damage by measuring the dark current of a sample diode fabricated from the film. It has been observed experimentally that when the sheath voltage was depressed from -73 V to -36 V at a pressure of 0.11 Torr, the dark current of the sample diode was suppressed drastically from 1.3 ×10−10 A to 5.3×10−11 A
Real-Time Surface and Near-Surface Optical Diagnostics for Epitaxial Growth
Authors: Aspnes D. E. 
Published: March 2011

AbstractVarious optical diagnostics are being developed to meet new challenges in semiconductor epitaxy. New data-analysis algorithms allow near-surface alloy compositions and interface properties to be obtained by kinetic ellipsometry (KE) without any knowledge of the underlying sample structure. New information about growth is being obtained by surface-oriented probes such as laser light scattering (LLS), surface photoabsorption (SPA), anrd reflectance-difference (-anisotropy) spectroscopy (RDS/RAS). Examples are provided and likely directions of further progress discussed.
Low Coherence Interferometry for Non-Invasive Semiconductor Monitoring
Authors: Lawson Chris M. , Michael Robert R. 
Published: March 2011

AbstractWe report on the first use of optical low coherence reflectometry (OLCR) for Edge Defined Film-Fed Growth (EFG) silicon characterization. This OLCR sensor system has been used to measure horizontal profiles of silicon thickness and flatness to an accuracy of 1.5 Rim with the sensor head positioned 1 cm away from the silicon. The use of this noninvasive sensor for EFG silicon growth monitoring may lead to more efficient solar cell manufacturing processes.
Study of Zener Diodes by Sem-DVC
Authors: Mil'shtein S. , Kharas D. , Iatrou S. 
Published: March 2011

AbstractA Scanning Electron Microscopy method called Dark Voltage Contrast (DVC) was applied for the first time to investigate on a microscale, the narrow depletion region of a Zener diode. Zener diodes were fabricated by the Sprague Semiconductor Corp. using conventional boron diffusion into a n-type wafer with phosphorus.Zener diodes were chosen because of the presence of a shallow p-n junction and for the ability of Zeners to work in the breakdown regime where the dynamics of the current might influence the field distribution in the p-n junction. The samples were examined in the SEM with a beam current below 50 pA to minimize injection of electrons into the depletion region.Reverse and forward biased diodes were examined and potential distribution information was obtained, using Dark Voltage Contrast software. Doping information and C-V measurements were used to double check DVC depletion region measurements.The main results of these studies include measurements of electrical field for three regimes of operation: forward, reverse, and breakdown, with almost ideal field distribution in some Zeners, and fluctuations in others. The field irregularities are related to the defects in the junction area. However the amount of charge build-up appears to depend on the current flow in the dynamic regime for the breakdown. The typical measurements of depletion region width were Wf=.14 μm when forward biased, Wr=0.35 μm at 3-4 volts when reverse biased and Wbr=0.44 gm for 6 v of breakdown. This data helps to reconstruct the diffusion profile.
Characterization of Polycrystalline Silicon Multilayers with thin Nitride/Oxide Films Using Spectroscopic Ellipsometry
Authors: Asinovsky L.M. 
Published: March 2011

AbstractSpectroscopic ellipsometry has been used to characterize oxide/poly-Si/oxide with thin nitride/oxide layer. Films were deposited on Si substrate using low-pressure chemical vapor deposition (LPCVD) techniques. The measurements were taken at angles of incidence of 65 and 70 degrees in the wavelength range from 300 to 800 nm. The analysis of the data using effective medium and two-dimensional Lorentz oscillator approximations identified complete recrystallization of the poly-Si after annealing and and its transformation to µ c-Si. Three wafers taken at the sequential stages of the manufacturing process were studied. Although parameters of the thin nitride/oxide layers are strongly correlated, reasonable estimates of the thicknesses were found. The resuilts were consistent with the measured Auger electron spectroscopy (AES) profiles.
Simulation of Dry Etching Processes for III-V Compounds Technology Applications
Authors: Ketata K. , Koumetz S. , Ketata M. , Debrie R. 
Published: March 2011

AbstractThis work introduces a new dry etching simulation technique of the sputtering component of Reactive Ion Etching (R.I.E.) and presents experimental verifications for GaAs. The final objective is to correlate the etch rate to the plasma reactor parameters, which can be incorporated into a computer-simulation program.
Reactive Ion Etching of GaN Thin Films
Authors: Manfra Michael , Berkowitz Stuart , Molnar Richard , Clark Anna , Moustakas T.D. , Skocpol W.J. 
Published: March 2011

AbstractReactive ion etching of GaN grown by electron-cyclotron-resonance, microwave plasma-assisted molecular beam epitaxy on (0001) sapphire substrates was investigated. A variety of reactive and inert gases such as CC12F2, SF6, CF4, H2/CH4 mixtures, CF3Br, CF3Br/Argon mixtures and Ar were investigated. From these studies we conclude that of the halogen radicals investigated, Cl and Br etch GaN more effectively than F. The etching rate was found to increase with decreasing pressure at a constant cathode voltage, a result attributed to larger mean free path of the reactive species.
Reactive-Ion-Etching of 100nm Linewidth Tungsten Features Using SF6:H2 and a Cr-Liftoff Mask
Authors: Shirey Loretita M. , Foster Kelly W. , Chu William , Kosakowski John , Rhee Kee Woo , Eddy Charles , Park Doewon , Isaacson I. Peter , Mccarthy Daniel , Marrian Christie R. K. , Peckerar Martin C. , Dobisz Elizabeth A. 
Published: March 2011

AbstractReactive ion etching of features down to 100 nm in linewidth in tungsten has been studied using an SF6 based chemistry. The studies were carried out in a PlasmaTherm 500 etcher operated at low pressure (2 mTorr) and power (100 mWatts/cm2). Key processing parameters have been identified to achieve the resolution and aspect ratio required for high contrast x-ray masks. The critical parameters include sample temperature, gas dilution and end point detection. However, even with all of these parameters optimized, additional sidewall passivation is required to obtain the necessary 6.5:1 aspect ratio. A novel method of achieving such passivation based on an intermittent etching process is described.
Spectral Reflectance as an in Situ Monitor for Mocvd
Authors: Breiland W G. , Killeen K. P. 
Published: March 2011

AbstractNear normal-incidence spectral reflectance has been used to monitor the growth of AlAs, GaAs, and AlGaAs thin films by MOCVD in real time. The method has been used in a research rotating disk CVD reactor and in a modified commercial horizontal channel reactor. Reflectance is simple, robust, and is insensitive to perturbations such as mechanical strains, wafer rotation, and imperfect windows commonly encountered in an actual MOCVD system. Data may be collected over a wide spectral range, 390 to 950 nm, in less than one second using a multichannel detector and broad-band light source. This wide bandwidth provides detailed compositional discrimination and greater thickness sensitivity than single-wavelength measurements. The technique may be used to extract wavelength-dependent optical constant data under growth temperature conditions. Examples from the growth of multi-layered structures used in the fabrication of Vertical Cavity Surface Emitting Lasers is presented. The method shows promise as a valuable tool in process modeling, optimization, and control.
Photoluminescence of Sige Alloys Implanted with Erbium
Authors: Erzgräber H.B. , Gaworzewski P. , Schmalz K. , Krôger D. , Morgenstern T. , Osinsky A. , Vatnik M. 
Published: March 2011

AbstractThe 1.54μm emission of erbium implanted SiGe alloys was investigated as a function of oxygen and germanium concentrations as well as defect densities. Samples of SiGe layers grown by atmospheric pressure chemical vapor deposition technique which contain high concentrations of grown-in oxygen in the 10 19 - 1020 cm−3 range and 2 - 24 % Ge were chosen for the experiments. By using rapid thermal annealing in nitrogen atmosphere, a high optical activation of Er was found by photoluminescence. In samples with low defect densities nearly one third of the implanted Er ion dose could be detected in form of electrically active donors by spreading resistance measurements. The behavior of different SiGe : Er layers, based on sample property and annealing condition, suggests that more than only one type of luminescent Er-complex is present.
Oriented Carbon Pair Defects Stabilized by Hydrogen in as-Grown GaAs Epitaxial Layers
Authors: Cheng Y.M. , Stavola M. , Abernathy C.R. , Pearton S.J. 
Published: March 2011

AbstractWe have studied the IR absorption of heavily carbon doped GaAs grown by metalorganic molecular beam epitaxy. A striking observation is that the hydrogen-stretching vibration of a Crelated complex at 2688 cm−1 is strongly polarized along just one of the <110> directions in the (001) growth plane. This polarized C-H vibration is assigned to a defect complex that is aligned at the growth surface and then maintains its alignment as it is incorporated into the growing crystal. In a series of experiments, we have studied the annealing of the 2688 cm−1 band and its alignment and suggest that the defect complex consists of a CAs-CAs pair stabilized by hydrogen.
Metastable Defects and Stretched Exponentials
Authors: Redfield David , Bube Richard 
Published: March 2011

AbstractMetastability of defects in semiconductors provides the basis for (1)An integrated picture of defects that includes the DX center in crystalline HI-V compounds, the dangling-bond defect in amorphous Si, and ‘self-compensation’ effects in I1-VI compounds. The unifying physical property is the ability of many foreign atoms to have two nearly equal-energy sites, one with a shallow electronic level and the other with a deep level. (2)Elucidation of stretched-exponential kinetics in these materials, including the first demonstrable microscopic model for them. This stretched-exponential model is a distribution of independent response times.
Characterization of Defects in N-Type 6H-SiC Single Crystals by Optical Admittance Spectroscopy
Authors: Evwaraye A.O. , Smith S.R. , Mitchel W.C. 
Published: March 2011

AbstractOptical admittance spectroscopy is a technique for measuring the conductance and capacitance of a junction under illumination as a function of the wavelength of the light and the frequency of the measuring AC signal. For the first time, this technique is applied to characterize deep defect levels in 6H-SiC:N. Nitrogen is a donor atom in 6H-SiC which substitutes for carbon in three inequivalent sites (h, kl, k2). giving rise to n-type conduction. Deep defect levels attributible to transition metal impurities have been identified in 6H-SiC:N by optical admittance spectroscopy.
Tuning of Energy Levels in a Superlattice
Authors: Peeters Francois M. 
Published: March 2011

AbstractThe gap between the minibands of a conventional superlattice (or between the subbands of a quantum well) can be controlled by introducing potential barriers in its wells. An appropriate choice of the position, the width d, and the height Vd of these barriers, achieved by standard methods, can reduce the energy minibands to the desired values. When these barriers are introduced at the center of the wells of the original structure, the position of the second miniband in energy space changes very little with d and/or Vd whereas that of the first miniband can change by one to two orders of magnitude. This leads to a tuning of the first miniband and of the energy gap between the first two minibands. Similar results are obtained for the case of wells in the barriers and for the tuning of impurity states in a superlattice. Possible applications include infrared photodetectors and tuning of the tunneling current.
Optical Properties and Electroluminescence of Ordered and Disordered ALAS/GAAS Superlattices
Authors: Arent D. J. , Alonso R. G. , Horner G. S. , Kibbler A. E. , Olson J. M. , Yin X. , Delong M. C. , Springthorpe A. J. , Majeed A. , Mowbray D. J. , Skolnick M. S. 
Published: March 2011

AbstractIn this study, we report the optical properties of a variety of compositionally equivalent disordered superlattices in the AlAs/GaAs system. Markedly different signatures are seen in the steady-state optical signatures of a random pseudobinary A10.5Ga0.5As alloy and (AlAs)n(GaAs)4-n superlattices (SLs) where n = 2 (ordered) or n is randomly chosen (disordered). Relative to the properties of the pseudobinary alloy or ordered SL, intense, redshifted, photoluminescence (PL) peaks and broad non-excitonic absorption are observed from disordered (AlAs)n(GaAs)4-n SLs where n is randomly chosen from the sets [0, 1, 2, 3, 4] or [1, 2, 3]. Our observations suggest that a large density of states at energies lower than the compositionally equivalent pseudobinary band gap exist, and including wider wells and barriers may lead strongly localized regions and the onset of quantum effects. Room temperature electroluminescence is also observed from disordered SL pn samples, and the energy, intensity, and efficiency are shown to vary with deposition sequence.
Performance of CVD and CVR Coated Carbon-Carbon in High Temperature Hydrogen
Authors: Adams J. W. , Barlettia R. E. , Svandrlik J. , Vanier P. E. 
Published: March 2011

AbstractAs a part of the component development process for the particle bed reactor (PBR), it is necessary to develop coatings which will be time and temperature stable at extremely high temperatures in flowing hydrogen. These coatings must protect the underlying carbon structure from attack by the hydrogen coolant. Degradation which causes small changes in the reactor component, e.g. hole diameter in the hot frit, can have a profound effect on operation. The ability of a component to withstand repeated temperature cycles is also a coating development issue. Coatings which crack or spall under these conditions would be unacceptable. While refractory carbides appear to be the coating material of choice for carbon substrates being used in PBR components, the method of applying these coatings can have a large effect on their performance. Two deposition processes for these refractory carbides, chemical vapor deposition (CVD) and chemical vapor reaction (CVR) have been evaluated.Screening tests for these coatings consisted of testing of coated 2-D and 3-D weave carbon-carbon in flowing hot hydrogen at one atmosphere. Carbon loss from these samples was measured as a function of time. Exposure temperatures up to 3000 K were used and samples were exposed in a cyclical fashion, cooling to room temperature between exposures. The results of these measurements are presented along with an evaluation of the relative merits of CVR and CVD coatings for this application.
Processing of Silicon Carbide Fiber with Controlled Stoichiometry Using Polymethylsilane, -[MeSiH]x-
Authors: Zhang Zhi-Fan , Scotto Cathy S. , Laine Richard M. 
Published: March 2011

AbstractPolymethylsilane (-[MeSiH]x-) synthesized from a single step catalytic polymerization of methylsilane (MeSiH3), provides a new route to near stoichiometric, microcrystalline silicon carbide fibers. The final composition is controlled by selected additives. The entire process simply contains 3 simple steps: (1) a single step synthesis of polymer precursor, (2) precursor fiber spinning, and (3) a single step pyrolytic conversion to target ceramic fibers.
Rapid Solid-State Precursor Synthesis of Non-Oxide Ceramics
Authors: Rao Lin 
Published: March 2011

AbstractRapid self-sustaining solid-state precursor methods have proven to be an effective route to non-oxide ceramics. With the appropriate choice of precursors, fine powders of crystalline BN, AIN as well as composites such as TiB2-TiN-BN can be formed easily within seconds. These materials are characterized by X-ray diffraction, scanning electron microscopy and elemental analysis (XPS, EDS, and conventional chemical methods). The synthetic techniques will be discussed along with characterization and numerical simulation results. Further applications of this technique will be proposed.
Microstructure and Densification of Sintered (B+C)-Doped β-Silicon Carbide
Authors: Braue Wolfgang , Kleebe Hans-J. , Wehling Carsten 
Published: March 2011

AbstractThe role of boron and carbon during densification of sintered β-SiC was investigated through the combined approach of in-situ dilatometry and CTEM/AEM inspection of TEM-foils referring to well-defined densification events. Preliminary data obtained indicate that in the early stages of densification, boron is not enriched in the continuous carbon-rich surface layer covering the β-SiC powder particles nor does it segregate to internal interfaces in high quantities. Small boron quantities are dissolved in the SiC grains- Simultaneously with the β- to α- phase transformation, decomposition of foam-like B4C aggregates releases small B4C particles, which are bound intragranularly to α-SiC.
Atomic Defects in Transition Metal Carbides and SiC Studied by Positron Annihilation
Authors: Rempel A. A. , Schaefer H. -E. , Forster M. , Girka A.I. 
Published: March 2011

AbstractNonstoichiometric defects in carbides of the Group IV and V transition metals and radiation-induced atomic defects in SiC were studied by positron lifetime measurements before and after low-temperature (80 K) electron irradiation and subsequent thermal annealing up to 1900 K. Agglomeration of radiation-induced atomic defects which strongly depends on the energy of the irradiation electrons and subsequent decay of the agglomerates in SiC is observed.
Gaseous Alkali Corrosion Kinetics of Silicon Carbide
Authors: Sun Tawei , Pickrell Gary R. , Brown Jesse J. 
Published: March 2011

AbstractThe gaseous alkali corrosion kinetics of α-SiC were systematically investigated from 950°C to 1100°C in an atmosphere containing 0.98 vol% sodium nitrate vapors. The reaction of the SiC in the alkali-containing atmosphere follows a linear rate law with an activation energy of 104 kJ/mol. The alkali corrosion is composed of dissolution of SiO2 in the sodium silicate liquid, oxidation of SiC, and adsorption of Na2O from the vapor phase. The overall reaction appears to be controlled by the oxidation at the SiC substrate/sodium silicate liquid interface.
Study on the Heat–Treatment Reinforcement of Aluminum Nitride–Silicon Carbide Composites
Authors: Ningfang Li , Hongquan Zhang , Guomei Wang 
Published: March 2011

AbstractThe effects of heat – treatment on the mechanical properties of AIN – SiC whisker composites with Y2O3 and SiO2 additives has been studied. When the sample containing 10 wt% Y2O3 +SiO2 (Y2O3/SiO2= 1/0. 66) was treated at 1300°C in air for 140 hours the strength of compositqs was raised from 481 MPa to 784 MPa.The phase composition, microstructure and grain boundary phase structure have been characterized by combining XRD, SEM, TEM/EDXA and HREM techniques. The reinforcement mechanism of the composites results from crystallization of the glass phase in the grain boundary at the high temperature oxidizing atmosphere to form the crossing structure of 2Hδ Sialon fibrous phase and SiC whisker.
Preparation and Characterization of Group 14 Element BIS(Thiolate) Compounds and Evaluation of Their Potential as Molecular Precursors in the Low Temperature Syntheses of Binary Metal Sulfides
Authors: KrÄuter Gertrud , Favreau Philippe , Nunnally Brian K. , Rees W. S. 
Published: March 2011

AbstractThree isomeric lead bis(butylthiolate) and tin bis(butylthiolate) compounds have been prepared and characterized. Their solid state decomposition, and in the case of the lead bis(thiolate) compounds, their thermolyses in suspension in a high boiling hydrocarbon, have been studied. X-ray powder diffraction patterns and scanning electron micrographs of the obtained solid state material are discussed. Volatile co-products of the decomposition have been isolated and characterized.
Electrical Properties of Alkyl-Trichlorosilane Monolayers Grafted on Silicon Substrate
Authors: Vuillaume Dominique , Rondelez Francis 
Published: March 2011

ABSTRACTWe demonstrate that a single monolayer of alkyl-trichlorosilane Molecules, covalently grafted to the native oxide of a silicon substrate, allows to fabricate silicon based MIS (Metal-Insulator-Semiconductor) devices with excellent electrical properties. The thickness of the organic monolayer is in the range 1.5–2.8 nm, corresponding to long alkyl chains with 8 to 18 carbon atoms. We have fabricated MIS capacitors with a leakage current density as low as 10-8 A/cm2 at 6 MV/cm, high dielectric breakdown field (12 MV/cm), electrically active defect density lower than 1011 cm-2, and low field dc conductivity as low as 10-16–10-15 Scm-1. Thermal stability has been demonstrated up to 450 °C.
Sulfur Containing Conjugated Polymers with Interesting Electronic Properties.
Authors: Elsenbaumer R. L. , Marynick D. S. , Seong S. , Meline R. L. 
Published: March 2011

ABSTRACTThe electronic properties of the isomerie (C2S2)n conjugated sulfur containing polymers 1, 2, and 3 were characterized using ab initio and PRDDO Molecular orbital calculations, as well as EH band structure calculations. It is anticipated that such structures might exhibit enhanced electrical conductivities when doped owing to the possibility of the peripheral sulfur atoms extending orbital interactions transverse to the chain axis direction. Such increased dimensionality is demonstrated for the structurally similar superconductive Molecular TTF and ET charge-transfer salts. Of the three polymeric structures, indications are that polymer 2 is highest in energy. Polymer 3 can exist in both “chair” and “boat” conformations, with the chair form slightly more stable. Both the chair and boat forms of 3 were found to be of lower energy than 1. Calculated band gaps and band widths are reported along with preliminary synthetic attempts to prepare these polymers and observed properties.