bluuebunny/crossref_metadata_2025_split huggingface dataset:
Deposition of Hydrogenated Si Films by Hydrogenation of the SiO2 Surface and Hydrogen Dilution with PE-CVD and ECR-CVD
Authors: Wang Kun-Chih , Yew Tri-Rung , Hwang Huey-Liang 
Published: April 2011

AbstractThis paper presents the results of low temperature deposition of poly-Si films deposited on SiO2 layers. Hydrogen dilution, hydrogen atom treatment, and hydrogenation of the SiO2 surface steps were applied to deposit the Si films. The above treatment steps were usually used in the plasma enhanced chemical vapor deposition and they were extended to be used in the electron cyclotron resonance chemical vapor deposition to identify the grain growth effects. The nucleation and microstructure of the silicon films were observed by cross-section transmission electron microscopy (XTEM).
Deposition and Crystallisation Behaviour of Amorphous Silicon Thin Films Obtained by Pyrolysis of Disilane Gas at Very Low Pressure
Authors: Kretz T. , Pribat D. , Legagneux P. , Plais F. , Huet O. , Magis M. 
Published: April 2011

AbstractHigh purity amorphous silicon layers were obtained by ultrahigh vacuum (millitorr range) chemical vapor deposition (UHVCVD) from disilane gas. The crystalline fraction of the films was monitored by in situ electrical conductance measurements performed during isothermal annealings. The experimental conductance curves were fitted with an analytical expression, from which the characteristic crystallisation time, tc, was extracted. Using the activation energy for the growth rate extracted from our previous work, we were able to determine the activation energy for the nucleation rate for the analysed-films. For the films including small crystallites we have obtained En ∼ 2.8 eV, compared to En ∼ 3.7 eV for the completely amorphous ones.
Challenges For Flat Panel Display Phosphors
Authors: Maruska H. P. , Parodos T. , Kalkhoran N. M. , Halverson W. D. 
Published: April 2011

AbstractPhosphors are a class of materials which emit visible light when impacted by either electrons or photons. Phosphors are the critical material in all self-emissive displays. The major display technologies which depend on phosphors are cathode ray tubes, flat cathode ray tubes (especially, field emission displays), thin film electroluminescent displays, and gas discharge plasma displays. Each of these technologies started with phosphors prepared in powder form, sprayed or screen printed onto a faceplate suitable for viewing. Electroluminescent displays have largely converted to thin film phosphors. It can be expected that, for many applications, the other competing technologies will also come to rely on more robust, high definition, thin film phosphors. Presently, full color displays must utilize several deposition and etching procedures to prepare the red, green, and blue pixels. Ion implantation of color centers is now paving the way for producing full color displays in a single host phosphor. We shall discuss the present limitations that compromise full color self-emissive displays, and present state-of-the-art solutions based on thin films and ion implantation.
Effect of Ion Doping Temperature on Electrical Properties of APCVD A-Si
Authors: Lee Kyung Ha , Moon Byeong Yeon , Chung Yoo Chan , Lee Seung Min , Kim Sung Chul , Kim Donggil , Jang Jin 
Published: April 2011

AbstractWe have studied the effect of ion doping on the electrical properties for atmospheric pressute chemical vapor deposition (APCVD) amorphous silicon (a-Si) films. The room temperature conductivities after ion doping at optimurr doping tenperatures for n− and p-type a-Si films were found to be > 10−2 and >10−4 S/cm, respectively. The unintentional hydrogen incorporation into a-Si during ion doping enhances the quality of ion doped APCVD a-Si as compared to that of plasma enhanced CVD (PECVD) a-Si:H. We obtained the field effect mobility of > 1 cm2/Vs for APCVD a-Si TFT using ion doped n+-layer.
Progress in Large Area Selective Silicon Deposition for TFT/LCD Applications
Authors: Souk Jun H. , Parsons Gregory N. 
Published: April 2011

AbstractWe have previously demonstrated selective area deposition of n+ microcrystalline silicon at 250°C using time modulated silane flow into a hydrogen plasma, and applied the technique to form high performance top-gate amorphous silicon TFT's with two mask sets. In this paper, we discuss issues related to process scale-up, including the effect of deposition rate on selectivity loss and non-uniformity. Uniformity can be achieved with higher growth rates by expanding the window for selectivity, and using conditions well within the process limits. We show that lower pressure and higher rf power can enlarge the window by enhancing the hydrogen-mediated silicon etching.
A Low Temperature Plasma-Assisted Deposition Process for Microcrystalline Thin Film Transistors, TFTS
Authors: He S. S. , Lucovsky G. 
Published: April 2011

AbstractThe drive-current of low-temperature (∼300°C) deposited TFTs has been increased by replacing the a-Si:H channel, and source and drain materials with μc-Si. Lightly B2H6 doped, near-intrinsic μc-Si has been used as the channel layer of the TFTs, and n+ μc-Si was used for the source and drain contacts. The compensation of intrinsic defects in the undoped μc-Si by boron doping increases the dark conductivity activation energy from ∼0.35 eV to 0.8 eV. TFI's were fabricated in a bottom gate structure, and required an H2 plasma treatment to produce devices with effective channel mobilities of ∼6.8 cm2/V-s and threshold voltages of ∼3.7 V in the saturation region.
Effect Of O2 Plasma Exposure On The Performance Of Polycrystalline Silicon Thin Film Transistors
Authors: Kim Chul Ha , Lee Il , Sohn Ki Soo , Chun Su Chul , Jang Jin 
Published: April 2011

AbstractWe have studied the effect of O2 plasma exposure on the performance of polycrystalline silicon (poly-Si) thin film transistor (TFTs). The field effect mobility is increased and the drain currents at negative gate voltages are reduced by O2 plasma exposure on the surface of the TFT. These improvements in the performance of the poly-Si TFTs are larger in offset structure compared to overlap one. We obtained the on/off current ratio of ∼ 108 after O2 plasma exposure for the poly-Si TFTs with 3 or 4 μm offset length.
Overview Activities Within the Eug at the University of Cambridge
Authors: Metaxas Andrew C. 
Published: April 2011

ABSTRACTElectricity today plays a prominent role in many diverse processes in manufacturing and other industries. Understanding the fundamental principles behind a host of electrically driven processes is the remit of electroheat as an academic discipline. Centres of electricity utilisation at Universities, funded by the electricity utilities, should be encouraged and supported at the embryonic stage of development in order to facilitate the transfer of the electroheat technology between industry and academe.
Open-Ended Coaxial Probes for Nondestructive Testing of Substrates and Circuit Boards
Authors: Baker-Jarvis James , Janezic Michael D. 
Published: April 2011

ABSTRACTThe results of the full-wave model theory for the open-ended coaxial probe with lift-off are presented and are applied to measurements of thin materials. The model allows the study of the open-ended coaxial probe as a nondestructive testing tool. The equations presented are valid for both dielectric and magnetic materials. The analysis yields insight into the effects of air gaps on probe measurements. Numerical results indicate that the probe is very sensitive to lift-off at low frequencies. This sensitivity decreases somewhat as frequency increases. In order for the field to penetrate the air gap, larger size coaxial line or higher frequencies need to be used. An application of the theory is performed by numerically solving the inverse problem using measured reflection coefficient.
FDTD Simulation of an Open-Ended Metallized Ceramic Probe for Broadband High-Temperature Dielectric Properties Measurements
Authors: Bringhurst Shane , Iskander Magdy F. , Gartside Paul 
Published: April 2011

ABSTRACTOpen-ended coaxial probes have been used in broadband dielectric properties measurements for several years. To aid in the ongoing numerical simulation and microwave sintering research at the University of Utah, we have found it necessary to make dielectric properties measurements up to temperatures as high as 1400 °C. The available cavity perturbation techniques were unsuitable in this application due to their relatively narrow band, and the available metal probes are also unsuitable due to the differential thermal expansions of the inner and outer conductors, which makes it difficult to carry out accurate and on-line calibration procedures for these probes.To help us achieve both broadband and high-temperature dielectric properties measurements, we have developed a new metallized ceramic coaxial probe. The detailed design of this probe is described and the metallization procedure is discussed.Also to optimize the design of the probe and in particular to increase the penetration of fields in samples under test and hence improve the probe sensitivity to variation in properties of a larger class of materials, and to determine the required minimum thickness of various samples to obtain accurate results, we modeled and simulated the probe performance using the Finite-Difference Time-Domain (FDTD) method. Results from the FDTD simulation are presented and some guidelines that may be used to optimize the design of the probe are discussed.
Complex Dielectric Constant as a Function of Frequency for a Liquid Hydrocarbon Fuel in the Microwave Region
Authors: Wiegand Donald A. , Murray Frank 
Published: April 2011

ABSTRACTThe incident, reflected and transmitted powers were measured and the reflection and transmission coefficients calculated for a liquid fuel. Two sizes of double ridge waveguide were used to cover the frequency ranges 2.5 to 7.5 and 7.5 to 18 GHz and corrections were made for waveguide losses. Strong interference effects were observed and the real part of the dielectric constant, ε', was obtained primarily from the separation of interference maxima and minima while the loss tangent, ε“/ε', was obtained by curve fitting to the normalized power loss. The final values of ε′ and ε“/ε′ were determined at each frequency by minimizing the difference between the experimental and theoretical values of the reflection coefficient and the normalized power loss. With increasing frequency ε' decreases and then becomes constant while ε“/ε' decreases throughout the frequency range within experimental accuracy.
Estimation of the Local Electric field inside an Isotropic Mixture.
Authors: Roussy Georges , Thiebaut Jean-Marie , Madi Med 
Published: April 2011

ABSTRACTAs a consequence of the BERGMAN - MILTON theory, which expresses the effective permittivity of a two phase mixture with an integral of a density function, it has been possible to evaluate the local electrical field strength inside a heterogeneous mixture. The developed formula can be used advantageously for modeling the local temperature inside a ceramic material during its microwave sintering.
Assessment of Microwave Permittivity for Detecting Fruit Maturity
Authors: Nelson Stuart O. , Forbus W. Roy , Lawrence Kurt C. 
Published: April 2011

ABSTRACTPermittivity measurements from 0.2 to 20 GHz were taken on fresh peaches of three varieties at three stages of maturity during the growing season to determine whether dielectric properties might be correlated with maturity. Other physical properties of the peach tissue, such as density, moisture content, firmness, and total soluble solids content, were also determined. Two indices, based on dielectric constant and loss factor values at 0.2 and 10 GHz were found to correlate with stage of maturity, but they were dependent on the variety, and further study is necessary to determine their practical usefulness.
FDTD Modeling of Realistic Microwave Sintering Experiments
Authors: Huang Zhenlong , Iskander Magdy F. , Tucker James , Kimrey Hal D. 
Published: April 2011

ABSTRACTComputer modeling and numerical simulation provide a valuable tool for providing guidelines towards a successful routine experimentation with microwave sintering of ceramics. It is also expected that continued efforts in numerical simulation will lead to establishing procedures for the scale up and commercial utilization of this new technology.In this paper, we utilize the FDTD technique to model sintering ceramics in multimode microwave cavities. The role of using process stimulus such as SiC rods on improving the uniformity of the microwave sintering process are also simulated. To help experimentally validate the obtained results, the FDTD electromagnetic power deposition results were combined with a 3D heat transfer program to calculate temperature distribution in samples and surrounding insulation. Results from the FDTD codes and comparisons with experimental measurements of sintering experiments are presented.To improve the efficiency of the simulation and achieve more accurate results, we developed a variable mesh FDTD code to help focus the numerical results and hence improve the resolution in critical sites inside the sintering oven. Detailed solution procedures are described. We solved some test geometries with the uniform grid and the developed variable mesh codes and compared the obtained results to validate and check the accuracy of the solution procedure. Results from these comparisons are presented.
Microwave Energy for Waste Remediation Applications
Authors: Schulz R. L. , Folz D. C. , Clark D. E. , Wicks G. G. 
Published: April 2011

ABSTRACTResults of research on the use of microwave energy for several waste remediation applications are discussed. Studies include; processing of simulated nuclear waste glass frits, the destruction/vitrification of electronic circuitry from commercial and defense applications, the decomposition of organic compounds and the possible use of microwave energy in off-gassing operations during the ashing of electronic circuitry. Results of leach tests on simulated nuclear waste glass are presented as well as results from preliminary tests on organic wastes.
Microwave System Design and Dielectric Property Measurements
Authors: Tinga Wayne R. 
Published: April 2011

ABSTRACTIn high temperature microwave systems, property variations of the process material can cover orders of magnitude causing significant changes in microwave coupling efficiency, heating rate, impedance matching, field strength and penetration depth. We created some first-order, temperature dependent models of these system parameters for a number of materials and calculated typical values over the temperature range of 0–1000 C. The results show that the input impedance of a resonator, the relative energy dissipation the power density and the penetration depth in the process material are strongly influenced by the temperature dependent dielectric constant. Process control algorithms require models of the system parameters and hence our models are useful for automated microwave processing systems. Moreover, it is shown that the relative dielectric loss factor of the process material can be monitored via the reflection coefficient of the microwave resonator containing the material.
Calcination of Metal Oxide/Activated Carbon Catalysts Under Electromagnetic Fields
Authors: Kim Hee Y. , Jeon Jong Y. 
Published: April 2011

ABSTRACTEffects of microwave heating were investigated for calcining metal-oxide precursors that were supported on an activated carbon. To obtain the heterogeneous metal oxide/activated carbon catalysts, calcination of the precursors impregnated onto the activated carbon was executed for 10 minutes at 300°C within a cavity of 2.45 GHz microwave. Such an electromagnetic treatment was compared with the calcination in a conventional muffle furnace. Activities for the oxidation of the benzene or oil adsorbed on the catalysts prepared by the two methods were examined with a micro-pulse reactor as well as with thermogravimetric analysis. Experiments revealed that the time required for the calcination in the electromagnetic field is much shorter than that in the muffle furnace. The catalytic activities in the low-temperature oxidation were also enhanced by the application of microwave in the calcination. In addition, the oxidative reaction of the adsorbates could be obtained without the activated carbon being burned. The microwave effects were outstanding for Co3O4/activated carbon catalysts.
Microwave Sintering of Metal-Ceramic and Ceramic-Ceramic Composites
Authors: Gerdes T. , Whxert-Porada M. 
Published: April 2011

ABSTRACTPolyphase ceramic and metal ceramic composites with at least one high dielectric loss component are potential candidates for application of microwave sintering, because of the high effectiveness of power dissipation and short sintering times. In order to identify material parameters essential for effective microwave sintering, different mixtures of conductive, semiconductive and insulating phases were investigated. When only a limited amount of a highly dissipative component is present, a modification of the grain size and morphology of the dissipative phase has been identified as major factor leading to optimized microwave heating behavior. Surprisingly, microwave sintering is also possible in the presence of a metallic liquid phase.
Microwave Sintering of Zirconia Toughened Mullite (ZTM)
Authors: Cai J. , Song C. Y. , Li B. S. , Huang X. X. , Guo J. K. , Tian Y. L. 
Published: April 2011

ABSTRACTMicrowave sintering of zirconia toughened mullite (ZTM) has been performed in a single mode applicator. In comparison with conventional sintering, microwave processing of ZTM leads to a higher density and finer grain size. Microstructure of microwave sintered ZTM was characterized by TEM and HRTEM techniques. The pinning of intergranular ZrO2 dispersoids retarded the grain growth of mullite matrix. The observation of a considerable number of trans-granular microcracks indicates that microcracking toughening is the main toughening mechanism for ZTM.
Use of Variable Frequency Microwave Energy as a Flexible Plasma Tool
Authors: Johnson A. C. , Rudder R. A. , Lewis W. A. , Hendry R. C. 
Published: April 2011

ABSTRACTThis paper reports on the use of frequency as a control parameter in the generation of microwave-excited plasmas for applications such as chemical vapor deposition, chemical vapor infiltration, or plasma etching. By changing the excitation frequency of a plasma in a multi-mode chamber, the locations of the maxima and minima of the power density within the chamber are also changed. This allows localization of the plasma discharge in the precise processing area desired in order to increase the process' efficiency. In a similar fashion, sweeping of the processing frequency during the process cycle can theoretically “scan” the plasma across an arbitrarily-shaped target surface. A series of experiments was conducted to evaluate the flexibility of variable frequency microwave energy as a plasma process tool. The results of these tests are presented.
Microwave Induced Plasma (MIP) Nitriding of Titanium Alloy
Authors: Doroudian M. , Samandi M. 
Published: April 2011

ABSTRACTTitanium alloys possess several attractive properties such as light weight, high strength and excellent corrosion resistance. However, wider application of these alloys, especially for load bearing components operating under sliding conditions, are restricted due to poor tribological (friction and wear) behaviour. It has been shown previously [1] that nitriding of titanium by using DC plasma is an effective means of increasing the hardness and reducing friction and wear. In this work nitriding response of titanium alloy (Ti-6A1–4V) was investigated using a Microwave Induced Plasma (MIP). The plasma was generated in a TM012 stainless steel cylindrical cavity using 1.5 kW power supply operating at 2.45 GHz. The cavity was water cooled and tuned by two sliding shorts. Nitriding experiments in nitrogen-hydrogen mixture at 70 to 100 torr pressure established that MIP provides an excellent mass transfer medium for nitriding titanium alloy. Furthermore, significant advantages over DC plasma have been discerned. For instance, reduced sputtering, uniformity of treatment and temperature stability can be cited. In this work, preliminary results of characterisation of MIP nitrided surfaces by x-ray diffraction and optical microscopy will be presented to demonstrate the effectiveness of MIP for nitriding titanium.
A Non-Thermal Vacancy-Drift Mechanism of Plastic Deformation of Grains in Ceramics During Microwave Sintering
Authors: Rybakov K. I. , Semenov V. E. 
Published: April 2011

ABSTRACTThe plastic deformation of grains is shown to take place due to the vacancy drift perturbations caused by space charge formation in the near-surface layer and by surface permeability asymmetry with respect to the direction of the motion of atoms through it.
Cerium-Doped Orthophosphate Scintillators
Authors: Wojtowicz A. J. , Lempicki A. , Wisniewski D. , Boatner L. A. 
Published: April 2011

ABSTRACTCerium-doped lutetium orthophosphate (LuPO4:Ce) is one of the most promising new scintillator materials. In this paper we report on the effects of total or partial replacement of Lu by Yb. When not doped with Ce, crystals of YbxLu1-xPO4 scintillate rather poorly, the emission being due to the Yb charge transfer transition. Activation with Ce reduces the light output from Yb even further, while correspondingly the addition of Yb to LuPO4:Ce also degrades that material's scintillation performance. We suggest that the nonradiative decay of the (Yb2+-Ce4+) charge transfer state is responsible for the mutual quenching of these ions. The differences in performance of LuPO4:Yb and LuPO4:Ce indicate that energy transfer mechanisms ordinarily associated with materials containing molecular anionic groups may not be quite sufficient to explain the results. Suggestions are presented that under γ-excitation the lattice-to-ion energy transfer in orthophosphates is accomplished by sequential capture of charge carriers rather than the more conventional mechanism of exciton hopping between molecular groups.
Fluorescence Properties of CeF3 and of Some Other Cerium Doped Crystals and Glasses Under VUV and X-RAY Synchrotron Excitation
Authors: Pedrini C. , Belsky A.N. , Vasil'ev A.N. , Bouttet D. , Dujardin C. , Moine B. , Martin P. , Weber M.J. 
Published: April 2011

ABSTRACTReflectivity and fluorescence excitation spectra and fluorescence decays of CeF3 and LaF3:Ce have been recorded and analyzed in the VUV range up to 120 eV and in the X-ray region using the synchrotron radiation. Dominant mechanisms are identified in various regions of excitation, leading to different shapes of the excitation spectra and typical profiles of the decay curves. Strong difference in the light yield of fluorides and oxides are shown and discussed in terms of relative energies of levels of cerium and of the valence and conduction bands of the solid compounds.
Luminescence Kinetics Of Orthorhombic PbF2
Authors: Alov D.L. , Rybchenko S.I. 
Published: April 2011

ABSTRACTAn extremely dense single crystal of PbF2 with the orthorhombic structure is an attractive material for use as a scintillator. Its luminescence properties are quite different from those of the currently well-known cubic PbF2 crystal. The spectroscopic study of orthorhombic and cubic monocrystals of PbF2 as well as of crystals of mixed structure containing both the orthorhombic and cubic phases is presented in the paper. The orthorhombic PbF2 luminescence contains a visual part with the rapid kinetics (≈100 ns) at temperatures near 100 K.