bluuebunny/crossref_metadata_2025_split huggingface dataset:
Emissivity-Independent Rapid Thermal Processing using Radiation Shields
Authors: Timans P. J. , Morishige R. N. , Wasserman Y. 
Published: April 2011

ABSTRACTSimple rapid thermal processing (RTP) system configurations, in which the wafer temperature is controlled by a pyrometer viewing the wafer's backside, are vulnerable to changes in the spectral emissivity of this surface. One method for emissivity-independent temperature control is to use an opaque plate beneath the wafer as a radiation shield, which masks the wafer's backside from the heating lamps and provides a target whose temperature can be monitored easily by a pyrometer or a thermocouple. Experimental studies of the dynamic temperature responses of the wafer and the shield are in good agreement with predictions from a theoretical model based on a simple analysis of radiation heat transfer in the system. For the set of wafers studied here, pyrometer control of the shield temperature gave a spread of wafer temperatures of 4°C, as compared to a range of 160°C when the shield was not used. The radiation shield was also shown to give RTP process results which are immune to changes in wafer backside coatings.
Temperature Dependent Emissivity of Multilayers on Silicon
Authors: Abedrabbo S. , Ravindra N. M. , Chen W. , Rajasekhar V. , Golota T. , Gokce O. H. , Fiory A. T. , Nguyenphu B. , Nanda A. , Speranza T. , Maszara W. , Williamson G. 
Published: April 2011

ABSTRACTThe spectral transmittance, reflectance and emittance of silicon related materials and structures are measured simultaneously utilizing a spectral emissometer operating at near- and mid-IR spectral range and temperature range of 300 to 1500K. Several kinds of samples have been considered here: a) SiO2/Si with oxide in the thickness range of 653–5124A, b) SiO2/Si/ SiO2 with oxide thickness of 5000A on both front and back sides c)Multi-layers of SiO2/Si/ SiO2/poly-Si, with backside oxide of 1600A and 250A, respectively and d) separation by implantation of oxygen (SIMOX), with embedded oxide thickness of 4000A. An extensive analysis has been performed to interpret and compare the results obtained from these measurements.Concerning the SiO2/Si, we find that the experimental results are in accord with the sinusoidal relation of emissivity as a function of the silicon oxide thickness and hence the Applied Materials model. Experimental results on SiO2/Si/SiO2 are also presented here. For the multi-layers of SiO2/Si/SiO2/poly-Si, it is interesting to note that for temperatures above 600°C, the emissivity is independent of temperature and wavelength for the backside oxide thickness of 1600 and 250A. SIMOX measurements are presented as well. The Fiory model has been utilized extensively to investigate the high temperature emissivity data. The applications and limitations of this model are discussed.
Measurement of the Effective Mass of Transparent Conducting films of Cadmium Tin Oxide
Authors: Mulligan W. P. , Coutts T. J. 
Published: April 2011

ABSTRACTWe have prepared transparent conducting films of cadmium stannate (Cd2SnO4 with resistivity as low as 1.5×10-4 Ω cm. The resistivity of these films is low because of their surprisingly high mobility (60 cm2 V-1 sec-1) at high carrier concentration (7×1020cm-3). We conducted an investigation to determine whether the high mobility is due to unusually low carrier effective mass or to a long carrier relaxation time. The conductivity effective mass and relaxation time were estimated by Drude free-electron modeling of reflectance and transmittance spectroscopie measurements. The Drude model appears to represent the behavior of cadmium tin oxide very well. The optical effective mass of the electrons in cadmium stannate is about 0.35 mo, which is similar to that of other transparent conducting oxides. By varying the doping level, we were able to fabricate films with various levels of degeneracy, but these showed no significant difference in effective mass.We were also able to determine the carrier effective mass and the relaxation time by measuring four separate electron transport coefficients: conductivity, Hall, Seebeck, and transverse Nernst-Ettingshausen (Nernst). The Fermi level was found to vary from 0.31 to 0.83 eV above the conduction band minimum, and the conduction band was very close to parabolic in this range, with m* ∼ 0.33 mo, in good agreement with the optical result. We conclude that the effective mass of electrons in cadmium stannate is similar to electrons in other transparent conducting oxides and that high mobility results from a relatively long carrier relaxation time.
Hot-Wire Hydrogen Passivation of Polycrystalline Silicon TFT's
Authors: Beldi N. , Le Bihan F. , Kis-Sion K. , Sarret M. , Mohammed-Brahim T. , Raoult F. , Rogel R. , Guillet J. , Bouree J. E. 
Published: April 2011

ABSTRACTPolysilicon N-channel TFT have been hydrogenated using the H2 dissociation on a hot tungsten filament. A post-annealing realized at the optimal temperature of 300°C is necessary to obtain interesting electrical TFT characteristics. Different TFT's sizes and geometries have been processed. The analysis of their characteristics shows that hydrogen preferentially diffuses through silicon oxide layer. The enhancement of the current in the ON-state shows that hydrogen atoms have passivated silicon oxide gate / polysilicon interface traps. The important reduction of the dependency of the OFF-state current with the reverse gate voltage shows that hydrogen atoms have passivated grain boundary traps near the interface in the channel region and in the drain sheet resistance region then reducing the trapped carrier emission.
Analytical Treatment of Field-Effect Conduction in Polysilicon thin film Transistors
Authors: Eccleston W. 
Published: April 2011

ABSTRACTThe drift of electrons in the channels of Thin Film Transistors is analysed for discrete grains separated by grain boundaries containing amorphous silicon. The model provides the relationship channel mobility and grain size. The relationship between drain current and the terminal voltages is also predicted. The model relates to normal high current region of transistor operation.
Performance of thin film Transistors on Unhydrogenated In-Situ Doped Polysilicon films Obtained by Solid Phase Crystallization
Authors: Mourgues K. , Raoult F. , Pichon L. , Mohammed-Brahim T. , Briand D. , Bonnaud O. 
Published: April 2011

ABSTRACTLow Temperature Unhydrogenated in-situ doped polysilicon Thin Film Transistors (LTUTFT) are made through two types of four-mask aluminium gate process. Silicon layers are elaborated by a Low Pressure Chemical Vapor Deposition (LPCVD) method and crystallized by a thermal annealing. Source and drain regions are in-situ doped. An Atmospheric Pressure Chemical Vapor Deposition (APCVD) silicon dioxide ensures the gate insulation. Two structures A and B are fabricated, the difference is that for sample B the undoped/doped polysilicon layer interface is suppressed.The structure of the polysilicon films is studied using Transmission Electron Microscopy (TEM) and Current-Voltage characteristics of both types of TFTs indicate electrical quality of the polysilicon films.The best electrical properties are obtained with the B type TFTs: a low threshold voltage (VT=1.2V), a low subthreshold slope (0.7 V/dec), a high On/Off state current ratio (107) for a drain voltage VDS= 1V, and a very high field effect mobility (≥100 cm2 /Vs). It is worth to notice that these good results are obtained without hydrogenation.
Enhancement of On/Off Current Ratio of Poly-Silicon TFT by Selective Laser-Induced Crystallization of Active Layer
Authors: Jeon Jae-Hong , Park Cheol-Min , Choi Hong-Seok , Kim Cheon-Hong , Han Min-Koo 
Published: April 2011

ABSTRACTWe have proposed the new poly-Si TFT which reduces the leakage current effectively by employing highly resistive a-Si region in the channel. The active layer of proposed device is crystallized selectively by employing excimer laser annealing while the both sides of channel near the source/drain are not recrystallized and remained as a-Si. Unlikely LDD or offset structure, the a-Si region which is designed to reduce the leakage current acts as the conduction channel of carriers under the ON state, so that the ON current is decreased very little. The selectively crystallized active layer can be fabricated by irradiating the excimer laser through ITO film of which transmittance at the wave length of laser is selectively adjusted. In the course of fabricating the proposed device, any additional photo masking step is not necessary and misalign problem is eliminated. The experimental results show that the ON/OFF current ratio of proposed poly-Si TFT is 106 while that of conventional one is 105.
Performance Study of 4-Inch Full Color Field Emission Display Devices
Authors: Kim J. M. , Hong J. P. , Park N. S. , Jung J. E. , Jin Y. W. , Ryu Y. S. , Kim J. W. , Choi J. H. , Kang J. H. , Jang J. E. , Gofinkel B. I. , Roussina E. V. 
Published: April 2011

ABSTRACTWe present performance results of 4-inch full-color field emission display (FED) devices which are constructed by using Spindt type arrays with 80,000,000 Mo-metal tips, spacers, uniquely-developed low voltage color phosphors. Spindt type microtips with less than 1.1 urn in hole size are fabricated using a total internal reflection (TIR) holographic lithograpy method. Each color phosphor is electrophoretically deposited on the ITO line. The spacer which is screen-printed is characterized by a 3-dimentional surface analysis system. Electron emission pattern and luminance test of each pixel without cross talk are analyzed under different gate voltages. In addition, the total pressure and residual gas distributions inside the panel are investigated at various gap sizes between the cathode and anode plates.
Flexible, Lightweight Steel-Foil Substrates For a-Si:H Thin-Film Transistors
Authors: Theiss S. D. , Wu C. C. , Lu M. , Sturm J. C. , Wagner S. 
Published: April 2011

ABSTRACTFor many flat panel display applications, traditional glass substrates for the TFT backplane are not sufficiently rugged. Therefore, we have begun to explore the use of steel foils as TFT substrates for emissive or reflective displays. We report the fabrication of high quality a-Si:H TFTs on lightweight, flexible 75 μm thick stainless steel foils. The electrical characteristics of the TFTs were good and were not significantly affected by either dropping over 15 meters to a concrete floor or being bent to a radius of curvature of 8.25 cm for a period of over 400 hours. Typical device characteristics were: ION/IOFF > 107, IOFF ∼ 1012 A, VT ∼ 3.2 V, and μEFF ∼ 0.9 cm2/Vs. We also discuss our recent work on the successful integration of organic light-emitting diodes (OLEDs) with TFTs on steel substrates, resulting in a new form of emissive display.
Band Model for Electron Emission from Diamond and Diamond-Like Carbon
Authors: Robertson J 
Published: April 2011

ABSTRACTThe band diagram is constructed for diamond on metal and diamond-like carbon on metal emitters, from data for electron affinities, Schottky barrier heights or band offsets. For diamond, there is a large offset for the conduction band at the back-contact, causing this to be the dominant barrier for emission. Nitrogen and perhaps grain boundaries reduce this barrier by forming a depletion layer of ionised donors, which narrows the tunnelling distance. In DLC, there is little conduction band offset at the back-contact, and the dominant barrier is at the surface. Nitrogen now lowers the emission barrier by raising the bulk Fermi level and lowering the work function. Unresolved problems are also pointed out.
Sputter Deposition of Nanocones for Field Emission
Authors: Jankowski Alan F. , Hayes Jeffrey P. 
Published: April 2011

ABSTRACTDeposition into micron-sized holes is known to produce cone shapes as supported on substrates. Potential uses for the cones include field-forming devices as field ionizers and field emission cathodes. The application of such devices include flat panel displays and flash x-ray tubes. Process iterations to closely space arrays of sharp cones have been extensively documented during the past two decades using the physical vapor deposition method of evaporation. Sputter deposition is well known as a method to fill holes and trenches but has only recently been demonstrated as an alternative method to produce field emission cathodes. In a further reduction in size, we have been successful in demonstrating the ability to deposit a cone shape into a cavity with a 300nm diameter hole. Through comparison to the results of electron-beam evaporative deposition, a sputter deposited nanocone appears to be suitable for use as a field emission cathode.
Microstructure and Luminescence Properties of ZnS:Cu Powders and Electroluminescent Lamps
Authors: Sangaletti Luigi , Depero Laura E. , Allieri Brigida , Antonini Livio , Fantini Roberto , Bettinelli Marco 
Published: April 2011

ABSTRACTWe report on a microscopy and diffraction study of commercially available Cu-doped ZnS powders, along with an optical spectroscopy study of electroluminescent lamps fabricated with these powders. The results allowed us to identify a correlation between the microstructure and the optical properties (i.e. photoluminescence) of the ZnS powders. It is found that the best powders for EL lamps are those displaying a prevalent cubic, i.e. zincblend, structure, while the poor performances of the mixed phase (cubic + hexagonal) are tentatively ascribed to the quenching of luminescence due to defects (stacking faults) introduced into the cubic structure and resulting in a considerable amount of hexagonal phase, as detected by XRD. The mostly cubic powders have been selected to realize EL lamps. The optical properties of these lamps have been investigated by photoluminescence and electroluminescence spectroscopies with the aim to identify the degradation mechanisms leading to a decrease of brightness. The quenching of electroluminescence is primarily ascribed to a deterioration of the electrical contacts. However, the reduced brightness in photoluminescence spectra seems to indicate that additional quenching of luminescence is induced by transformations at the emitting layer of the lamps. This degradation is tentatively ascribed to the presence of voids in the emitting layer, which might induce, acting as traps for moisture, transformations in the optical and electrical properties of the transparent electrode (ITO).
Blue Electroluminescent Devices Fabricated from Silicon and Germanium Nanocrystals
Authors: Delgado Gildardo R. , Lee Howard W. H. , Pakbaz Khashayar 
Published: April 2011

ABSTRACTBlue electroluminescent (EL) devices were fabricated with Si nanocrystals produced by ultrasonic fracturing of porous silicon (PSi) as well as silicon and germanium nanocrystals synthesized through a control chemical reaction. The active EL material consists of Si and Ge nanocrystals embedded in various host matrices such as polyvinylcarbazole (PVK), polymethylmethacrylate (PMMA), silica sol-gels and other organic polymers and small organic molecules. Several device configurations were used to induce EL processes that rely on radiative electron-hole recombination within the nanocrystals. We report on the optical and electrical properties of these devices. Applications for these EL devices include highly efficient light emitting devices. The cost and ease of processing of these material systems make them potentially ideal for flat panel display applications.
Full-color Thin Film ZnGa2O4 Phosphors by Ion Implantation
Authors: Kalkhoran N. M. , Trivedi D. A. , Halverson W. D. , Vernon S. M. 
Published: April 2011

ABSTRACTFull-color cathodoluminescence (CL) characteristics of ion implanted ZnGa2O4 thin film phosphors deposited by rf sputtering have been investigated. High brightness red (R) and green (G) CL was obtained from Eu and Mn-implanted ions, respectively. Blue (B) emission has been achieved by Ce ion implantation or from high temperature annealed, self-activated films. RGB emissions of ion implanted ZnGa2O4 thin film phosphors are well saturated and enclose a larger area surrounding the central “white” zone of CIE chromaticity chart than standard CRT phosphors. Luminescence efficiency enhancements of up to 40% have been achieved through surface texturing of the substrate prior to phosphor deposition. First demonstration of bright luminescence in ion implanted ZnGa2O4 films on flexible polyimide substrates is reported.
The Application of Poly(Phenylene) Type Polymers and Oligomers in Electroluminescent Color Displays
Authors: Tasch S. , Brandstätter C. , Graupner W. , Hampel S. , Hochfilzer C. , List J. W. E. , Meghdadi F. , Leising G. , Schlichting P. , Rohr U. , Geerts Y. , Scherf U. , Müllen K. 
Published: April 2011

ABSTRACTDue to their high photoluminescence efficiency (>30%), high environmental stability and the good charge transport properties the derivatives of poly(paraphenylene) (PPP), as the laddertype PPP (LPPP) and the oligomer hexaphenyl, are very suitable materials to realise efficient, stable, large area blue organic light-emitting diodes (OLEDs). The emission of blue OLEDs can be efficiently converted into all other emission colors either by an external color conversion technique (ECCT) or an internal color conversion technique (ICCT) and hence are very interesting for a number of display applications:Firstly, we demonstrate the realisation of efficient red-green-blue (RGB) emission colors (representing the RGB-pixels in a multicolor display) by an external CCT. In this case the blue EL device is covered with highly fluorescenct dye/matrix layers, which are excited by the blue emission and emit photoluminescence light in a lower energetic range.Secondly, a new method for producing efficient white light-emitting polymer diodes (which are interesting for e.g. backlight sources in liquid crystal displays) based on a blend of two polymers is presented: a blue light-emitting m-LPPP and a red-orange emitter poly(perylene-co-diethynylbenzene) (PPDB). The red-orange emission is created within the EL device (ICCT) by an excitation energy transfer from m-LPPP into the energetically lower lying states of PPDB. This internal excitation energy transfer is very efficient, so that only a concentration of 0.05 weight % PPDB in the polymer blend is required in order to obtain white light emission.
Spray-Deposited Metal Oxide Films with Various Properties for Micro- and Optoelectronic Applications: Growth and Characterization
Authors: Malik A. , Séco A. , Nunes R. , Vieira M. , Fortunato E. , Martins R. 
Published: April 2011

ABSTRACTThis work reports the structure and electro-optical characteristics of different metal oxide films obtained by spray pyrolysis on heated glass substrates, aiming their application in optoelectronic devices. The results show that this technique leads to thin films with properties ranging from dielectric to degenerate semiconductors, offering the following advantages: simplicity, low cost, high productivity and the possibility of covering large areas, highly important for large area device applications.
Phase Equilibria and Properties of Transparent Conductors in the Indium-Tin-Zinc Oxide System
Authors: Palmer George B. , Poeppelmeier Kenneth R. , Edwards Doreen D. , Moriga Toshihiro , Mason Thomas O. , Schindler Jon L. , Kannewurf Carl R. 
Published: April 2011

ABSTRACTSolid state bulk processing techniques were used to synthesize various transparent conducting oxides (TCO's) with In, Zn, and Sn cations. Optical and electronic properties of resultant phase-pure TCO's were compared to each other and to bulk samples of Sn-doped In2O3 (ITO). Reduction and heat treatment showed significant effects on optical and electronic performance, indicating optimization of processing conditions will be required for industrial applications.Comparison of optical and electronic properties in the series of compounds: ZnkIn2O3+k, k = 3,4,5,7,11 revealed trends correlated with the materials’ internal structure. These layered compounds showed improvement of optical properties at higher Zn contents and improvement in conductivity at higher In contents. The trends suggest these materials may be useful for applications where tradeoffs between conductivity and transparency are acceptable.
Measurement of Strain Associated with Defects in SiTiO3 Bicrystals using Near-Field Scanning Optical Microscopy
Authors: McDaniel E. B. , Hsu J. W. P. 
Published: April 2011

ABSTRACTWe incorporate a polarization modulation technique in a near-field scanning optical microscope (NSOM) for quantitative polarimetry studies at the nanometer scale. Using this technique, we map out stress-induced birefringence associated with submicron defects at the fusion boundaries of SiTiO3 bicrystals. The strain fields surrounding these defects are larger than the defect sizes and show complex spiral shapes that break the reflection symmetry of the bicrystal boundary.
Effects of Lattice Distortion, Polaron Conduction and Double-Exchange Interaction on the Physical Properties of Magnetoresistive Manganites and Cobaltites
Authors: Yeh N.-C. , Vasquez R. P. , Wei J. Y. T. , Fu C-C. , Beach G. , Huynh J. , Samoilov A. V. , BoriS A. V. , Kovaleva N. N. , Bazhenov A. V. 
Published: April 2011

ABSTRACTThe relevance of lattice distortion, polaron conduction, and double-exchange interaction to the occurrence of colossal magnetoresistance (CMR) is investigated by comparing the physical properties of magnetoresistive manganites and cobaltites. The samples studied in this work include epitaxial films and ceramics of manganites with both A- and B-site substitution, (La0.7Ca0.3MnO3, LaMn0.7 Ni0.3O3, LaMnO.5Ni0.5O3), as well as epitaxial films and ceramics of cobaltites (La0.5Ca0.5CoO3). The structural, chemical, electrical transport, magnetic, optical properties and tunneling spectroscopy are studied. Based on our experimental results, we conclude that both double-exchange interaction and strong electron-phonon coupling due to the Jahn-Teller effect are essential to the occurrence of CMR.
Growth and Magnetic Structure of La0.67Sr0.33MnO3 Films
Authors: Brown G. W. , Jia Q. X. , Peterson E. J. , Hristova D. K. , Hundley M. F. , Thompson J. D. , Maggiore C. J. , Tesmer J. , Hawley M. E. 
Published: April 2011

ABSTRACTGrowth of LaMnO3 films that exhibit colossal magnetoresistance (CMR) has concentrated heavily on Ca doped materials. However, since the 33% Sr doped films are ferromagnetic at room temperature, they are ideal candidates for dual growth-magnetic structure studies using scanned probe techniques. In this study, interest was focused on the relations between growth/processing parameters, film morphology, and electronic/magnetic properties. In addition, films were grown on both LaA1O3 (LAO) and SrTiO3 (STO) to examine the results of stress induced by different substrate mismatches. La0.67Sr0.33MnO3 (LSMO) was grown using pulsed laser deposition (PLD) at temperatures between 500 °C and 800 °C. The film microstructure, crystallinity, and magnetic and electrical properties were characterized by room temperature scanning tunneling microscopy (STM), atomic force microscopy (AFM), magnetic force microscopy (MFM), x-ray diffraction, and temperature dependent transport and magnetization measurements. The growth trends follow those previously reported for Ca doped films. Grains increase in size with increasing temperature and coalesce into extended layers after annealing. Although topographic contributions complicate interpretation of some MFM data, local magnetic structure observed here is generally associated with film defects.