bluuebunny/crossref_metadata_2025_split huggingface dataset:
Application of Thin-Film Micromachining for Large-Area Substrates
Authors: Boucinha M. , Chu V. , Soares V. , Condee J. P. 
Published: April 2011

AbstractSurface micromachining is used with amorphous silicon, microcrystalline silicon, silicon nitride and aluminum films as structural materials to form bridge and cantilever structures. Low temperature processing (between 110 and 250 °C) allowed fabrication of structures and devices on glass substrates. Two processes involving different materials as the sacrificial layer are presented: silicon nitride and photoresist. The mechanical integrity of the fabricated structures is discussed. As examples of possible device applications of this technology, air-gap thin film transistors and the electrostatic actuation of bridges and cantilevers are presented.
Deposition of High Quality Amorphous Silicon by a New “Hot Wire” CVD Technique
Authors: Morrison Scott , Coates Ken , Xi Jianping , Madan Arun 
Published: April 2011

AbstractFor the “Hot Wire” chemical vapor deposition technique (HWCVD) method to be applicable for photovoltaic applications, certain critical technical issues need to be addressed and resolved such as: lifetime of the filaments, reproducibility, large area demonstration of the material and stable devices. We have developed a new approach (patent applied for) which addresses some of these problems, specifically longevity of the filaments and reproducibility of the materials produced. The new filament material used has so far shown no appreciable degradation even after deposition of >200 μm of amorphous silicon (a-Si). We report that this can produce “state-ofthe-art” a-Si with a dark conductivity of <10-10 (Ohm*cm)-1 and photoconductivity of >10-5 (Ohm*cm)-1 this material can also be doped p- or n-type. We also provide data using XRD as well as the Raman spectra. These materials have been incorporated into simple Schottky barrier structures. The development of microcrystalline silicon materials is also discussed.
Properties of Electron Emitting Diode Fabricated with Single-Crystalline Diamond
Authors: Ito Toshimichi , Nishimura Masaki 
Published: April 2011

ABSTRACTHighly efficient electron emitting diodes have been fabricated using single-crystalline diamond films epitaxially grown on high-pressure synthesized (100) diamond. These diodes have an internal electrode of a graphitized layer buried below an overgrown diamond layer with a very high resistivity, the structure of which is formed by a combination of heavy ionimplantation and overgrowth techniques. The efficiency of electron emissions from sufficiently hydrogenated p-type diamond surfaces reached 100% in the best case. It is found that H atoms can passivate internal defects created during the ion implantation process. The mechanism of the high efficiency is discussed in relation to electron-hole creations in the thin diamond layer under extremely high electric fields of 107 V/cm.
Fabrication of Planar Diamond Electron Emitters for Flat Panel Displays
Authors: Kawamura H. , Kato S. , Maki T. , Kobayashi T. 
Published: April 2011

ABSTRACTA planar electron emitter was fabricated employing chemical vapor deposited (CVD) diamond thin films. This device is composed of CVD diamond films selectively deposited on a pair of patterned Au/Cr films separated 2 micrometers from each other. When the driving voltage (Vd) was applied between the Au/Cr films, the extremely low threshold emission from diamond film was observed (Vd ∼ 10 V). Furthermore, by applying high voltage on anode screen placed above this device, part of emitted current was drawn to the anode and the luminescence from phosphors was clearly seen under Vd = 50V. The mechanism of electron emission from the diamond films used in this device was also discussed by comparing with the electron emission from isolated diamond particles. It was found that the effective work functions differ between the isolated particles and the continuous films. This result suggests a difference in the emission site of electrons.
Changes of Contact Potential Difference Induced by Frictional Damage in Ultrahigh Vacuum
Authors: Zhang L. , Nakayama K. 
Published: April 2011

ABSTRACTThe work function is one of the most fundamental properties of a metal surface. To clarify frictional electrification phenomena, the effects of frictional damage on the contact potential difference (CPD), which is defined by the difference between the work functions of two contacting surfaces, were investigated. Au(111) and Si(111) surfaces were scratched in an ultrahigh vacuum under a light load with the Si cantilever tip of an atomic force microscope. The contact potential difference between the scratched surface and the tip whose work function was known was measured using an ultrahigh vacuum scanning Kelvin probe force microscope (SKPM). Simultaneously, the noncontact atomic force microscope (NC-AFM) images were observed in situ. The CPD images showed clear changes between the areas with and without scratching, corresponding to the scratching track on the NC-AFM images.
Ito/A-Si:H Schottky Photodiode With Low Leakage Current And High Stability
Authors: Ma Qinghua , Nathan Arokia , Murthy R.V.R. 
Published: April 2011

ABSTRACTWe report the design, fabrication, and characterization of an indium tin oxide/hydrogenated amorphous silicon (ITO/a-Si:H) Schottky photodiode based on room temperature deposition of ITO. The optical transmittance of the ITO is larger than 80% in the visible light range and its resistivity is less than 6 x 10-4 Ω-cm. The fabricated photodiode exhibits low leakage current and stable I-V characteristics. The leakage current is 7x10-10 A/cm2when biased at -2 V and the shift in leakage current stabilizes to a value less than 9% after 2 seconds of biasing at -2 V. The improvement in performance can be attributed to the high integrity ITO/a-Si:H interface achieved with the low temperature deposition.
Properties of Image Sensor Structure Obtained Below 120°C On The Foil By Reactive Magnetron Sputtering
Authors: Kolodziej A. , Krewniak P. , Tadeusiewicz R. 
Published: April 2011

ABSTRACTPolyimide substrates are of interest because of their thermal stability, light weight, and good mechanical characteristics. This paper reports thermal control multilayer deposition experiments which have strongly affected the properties of the image sensor structure (TFT + photodiode). Particularly TFT properties have been studied with respect to difficulties of obtaining of good quality a-SiNx:H films at temperature below 120°C. We characterize the structural properties using infrared absorption, refractive index measurements, small angle x-ray diffraction and the optoelectrical measurements of the TFT and PIN diode structure. The linear image sensor consisting of two rows, 40 pixels per row, with dimensions 0.6 mm2was made on the polyimide foil.
Large Area, Full-Color Image Sensors Made with Organic Semiconductors
Authors: Yu G. , Srdanov G. , Wang J. , Heeger A.J. 
Published: April 2011

ABSTRACTLarge area polymer photodiode arrays were designed and fabricated for full-color imaging applications. These sensor arrays are of high photosensitivity, low dark current, large dynamic range and fast response time. The red, green and blue color primaries were achieved by coupling a set of color filters with the polymer sensor pixels with broad response covering entire visible spectrum. Image recovery process from the pixel photocurrent data was developed, which is suitable generally to image arrays with power-law light intensity dependence and with finite pixel dark current. Large sensing length photodiode arrays (2.5”5”) were fabricated with pixel densities from 40 to 100 dot-per-inch. They were used as the sensing elements in page size document scanners. Voltage switchable polymer photodetectors were developed. Their photosensitivity can be switched on and off with external bias. These devices can be used as the sensing elements in x-y addressable two-dimensional sensor matrices. The high on/off switching ratio and high photocurrent/dark-current ratio allow such two-dimensional, passive photosensor matrices be used for image sensing applications.
Fluorescent Hexacatenar Liquid Crystals
Authors: Hoag Ben , Gin Douglas L. 
Published: April 2011

ABSTRACTA novel family of phasmidic liquid crystals incorporating an oligo(p-phenylenevinylene) core was produced. These compounds exhibit blue luminescence in both solution and the solid state. The emission profiles are influenced by the degree of organization in the solid state. The snthesis and liquid-crystalline behavior of these compounds will be discussed. Their photophysical properties, as studied by c.w. photoluminescence excitation, emission spectroscopy, and site selective spectroscopy, as well as their optoelectronic properties will be presented.
Secondary Electron Emission Studies of Diamond and GaN Materials
Authors: Yater J.E. , Shih A. , Katzer D.S. 
Published: April 2011

ABSTRACTSecondary electron emission spectroscopy is used to examine the transport and emission of low-energy electrons in several wide bandgap materials. In particular, the secondary emission properties of C(100), C(111), and CVD diamond samples are compared in order to examine the effect of crystallographic orientation on the emission characteristics. Very high yields are obtained from hydrogenated and cesiated negative-electron-affinity surfaces of all three samples, indicating that low-energy electrons are transported and emitted very efficiently in the diamond materials. While the energy distribution of the emitted electrons is found to be sharply peaked at low energy for all three samples, the energy distributions measured from the C(111) surfaces are broader and reveal structure in the energy gap. The different emission processes at the C(100) and C(111) surfaces may account for the energy distributions observed from the polycrystalline CVD diamond. Finally, initial secondary emission measurements are taken from GaN and AlGaN films grown by molecular beam epitaxy. The secondary emission is not as strong as from the diamond samples, and the measurements reveal the impact of interface and surface barriers on the emission process.
Electron Field Emission from Undoped and Doped DLC Films
Authors: Litovchenko V.G. , Evtukh A.A. , Klyui N.I. , Litvin YU.M. , Kudzinovsky S.Yu. , Chakhovskoi A.G. , Felter T. E. 
Published: April 2011

ABSTRACTElectron field emission and electrical conductivity of undoped and nitrogen doped DLC films have been investigated. The films were grown by the PE CVD method from CH4:H2 and CH4:H2:N2 gas mixtures, respectively. By varying nitrogen content in the gas mixture over the range 0 to 45%, corresponding concentrations of 0 to 8 % (atomic) could be achieved in the films. Three different gas pressures were used in the deposition chamber: 0.2, 0.6 and 0.8 Torr. Emission current measurements were performed at approximately 10−6 Torr using the diode method with emitter-anode spacing set at 20 gm. The current - voltage characteristics of the Si field electron emission arrays covered with DLC films show that threshold voltage (Vth) varies in a complex manner with nitrogen content. As a function of nitrogen content, Vth initially increases rapidly, then decreases and finally increases again for the highest concentration. Corresponding Fowler-Nordheim (F-N) plots follow F-N tunneling over a wide range. The F-N plots were used for determination of the work function, threshold voltage, field enhancement factor and effective emission area. For a qualitative explanation of experimental results, we treat the DLC film as a diamond-like (sp3 bonded) matrix with graphite-like inclusions.
Field Emission from Carbon Films Deposited by VHF CVD on Different Substrates
Authors: Kosarev A.I. , Abramov A.S. , Vinogradov A.J. , Shutov M.V. , Felter T.E. , Andronov A.N. , Robozerov S.V. 
Published: April 2011

ABSTRACTAs previously demonstrated, non-diamond carbon (NDC) films deposited at low temperatures 200-300 °C on silicon tips reduced the threshold of field emission. In this paper we will present the results of the study of field emission from flat NDC films prepared by VHF CVD. Emission measurements were performed in a diode configuration at approximately 10−10 Torr. NDC films were deposited on ceramic and on c-Si substrates sputter coated with layers of Ti, Cu, Ni and Pt. The back contact material influences the emission characteristics but not as a direct correlation to work function. A model of field emission from metal-NDC film structures will be discussed.
Band-Bending Effects on Field Electron Emission From N- and P-Type Silicon Gated Emitter Tips
Authors: Matsukawa T. , Tokunaga K. , Kanemaru S. , Itoh J. 
Published: April 2011

ABSTRACTField emission characteristics from n- and p-type silicon gated emitter tips have been investigated in detail by means of experiments and theoretical estimation of band-bending induced by surface states. Single-tip emitters have been fabricated from n- and p-type silicon and their current-voltage characteristics have been evaluated. The field emission from the p-type emitter has been found to occur at lower extraction voltage than that of the n-type emitter. As the theoretical approach to the origin of the phenomena, potential distribution in the emitter tips has been calculated by using device simulation technique. The surface states of the n-type emitter tip are negatively charged and form a potential barrier against the electrons. On the contrary, there is no potential barrier in the p-type tips. The potential barrier in the n-type tip prevents electrons from reaching the tip apex. This is the reason why the emission current of the n-type emitter was suppressed lower than that of the p-type emitter.
Fluorescence line Narrowing Spectroscopy of Germanate Glasses Doped with Eu3+
Authors: Rolli R. , Samoggia G. , Speghini A. , Bettinelli M. , Montagna M. , Ferrari M. 
Published: April 2011

ABSTRACTIn the present paper we report on time-resolved resonant and non-resonant fluorescence line narrowing measurements on a lead germanate glass doped with Eu3+. Site-selective decay curves were measured at low temperature. The results show that energy transfer processes between Eu3+, ions in different sites are not efficient at the doping level under investigation (I mol% Eu2O3). The homogeneous linewidth of the 5D0→47F0transition was measured at room temperature as a function of the excitation energy within the inhomogeneous profile. The linear dependence of the homogeneous linewidth on the excitation energy is discussed.
Using Polymerised Nanocontacts to Improve the Electroluminescence of Porous Silicon
Authors: Chongt A.S.L. , Gan L.M. , Blackwood D.J. 
Published: April 2011

ABSTRACTA polyaniline contact layer was deposited via microemulsion polymerisation which resulted in nanosize short-chain polymer particles that penetrate deeper into the pores of porous silicon than polymers deposited by other more conventional methods. The microemulsion method gives a contact with higher chemical electroluminescence efficiency due to a larger area of actively emitting porous silicon.
High Field Limitation of Poole-Frenkel Emission Caused by Tunneling
Authors: Ganichev S. D. , Ziemann E. , Prettl W. , Istratov A. A. , Weber E. R. 
Published: April 2011

ABSTRACTThe electric field dependence of emission of carriers from deep impurities in semiconductors has been investigated applying static and terahertz electric fields. It is shown that at high electric field strengths carrier emission is dominated by phonon assisted tunneling which may easily be recognized by plotting the emission rate as a function of the square of the electric field strength in a log-lin plot giving a straight line. For charged impurities the transition from phonon assisted tunneling to Poole-Frenkel effect at low fields can be traced back.
THE EFFECT OF LEVEL MIXING IN Er-DOPED Si
Authors: Federighi M. , Kenyon A.J. , Chryssou C.E. , Pitt C.W. 
Published: April 2011

ABSTRACTWe have studied the effect of level mixing on the optical properties of Er in Si by calculating the radiative cross sections of Er in Si under external pressure, and the possibility of enhancing in this way both the luminescence and the excitation efficiency.
Optical Gain and Ion-Ion Interactions in Er/Yb Co-Doped Glasses
Authors: Federighi M. , Malla A. , Yeo K.-C. 
Published: April 2011

ABSTRACTWe have developed a model of Er/Yb co-doped glasses taking into account upconversion and concentration quenching. We show in this paper that co-doping with Yb does not affect the maximum gain attainable at very high pump power, but significantly enhances the pump efficiency at moderate pump levels.
Electroluminescence and Photoluminescence of Fluorenecarbazole Copolymer
Authors: Stephan O. , Vial J.C. 
Published: April 2011

ABSTRACTThin layers of poly(dihexylfluorene-co-N-hexylcarbazole) sandwiched between ITO and aluminium electrodes show stable photoluminescence and electro-luminescence at room temperature and ambient atmosphere. I(V) and Electro-luminescence versus voltage curves present a much lower threshold than device made up of poly(dihexylfluorene) homopolymer. When using the copolymer, the barrier height for hole injection is reduced to a value close to 0.17 eV to be compared to 0.83 eV for the homopolymer. This difference in offsets has been confirmed by electrochemical investigations.
Fluorescent Hexacatenar Liquid Crystals
Authors: Hoag Ben , Gin Douglas L. , Theissl Udo , Zojer Egbert , Leising Guenther 
Published: April 2011

ABSTRACTA novel family of phasmidic liquid crystals incorporating an oligo(ρ-phenylenevinylene) core was produced. These compounds exhibit blue luminescence in both solution and the solid state. The emission profiles are influenced by the degree of organization in the solid state. The snthesis and liquid-crystalline behavior of these compounds will be discussed. Their photophysical properties, as studied by c.w. photoluminescence excitation, emission spectroscopy, and site selective spectroscopy, as well as their optoelectronic properties will be presented.
ZnGa2O4 Thin-Film Phosphors Grown by Pulsed Laser Ablation
Authors: Lee Yong Eui , Rouleau Christopher M. , Park Chan , Norton David P. 
Published: April 2011

ABSTRACTThe growth and properties of undoped and Mn-doped ZnGa2O4 thin-film phosphors on (100) MgO and glass substrates using pulsed laser ablation were investigated. Blue-white and green emission were observed for as-deposited undoped and Mn-doped films, respectively. Luminescent properties as well as crystallinity were considerably affected by processing conditions and film stoichiometry. Films with enhanced luminescent characteristics were obtained on single crystal substrates without post-annealing.
Ultrafast Optical Responses of the Squarylium Dye J-Aggregates Films
Authors: Tatsuura S. , Furuki M. , Tian M. , Sato Y. , Pu L.S. 
Published: April 2011

ABSTRACTUltrafast optical responses of the organic films containing squaryliurn dye J-aggregates prepared by simple spincoating method were investigated. Some SQ films exhibited a sharp absorption peak originated from J-aggregates and especially the SQ derivative which has dibutylamino bases at the end of benzene rings forms good J-aggregates in the films without any extra treatment. Time-resolved difference absorption spectra were measured about the SQ44 film. Clear bleached absorption peak and its fast recovery were observed. The decay time was determined to be about 220 fs at 50 MW/cm2 excitation intensity. Sample preparations and all the measurements were performed in air at room temperature.
Determination of Crystallite Size and Lattice Strain in Hexaphenyl Thin Films by Line Profile Analysis
Authors: Brandt H.-J. , Resel R. , Keckes J. , Koppelhuber-Bitschnau B. , Koch N. , Leising G. 
Published: April 2011

ABSTRACTHexaphenyl thin films (HTF) are widely used as an electro-active organic medium in blue light emitting diodes. The optical parameters of the HTF-based devices significantly depend on their microstructural properties.HTF of different types are produced by physical vapor deposition on glass substrates applying specific sample preparation conditions. The microstructural properties of HTF are characterized using X-ray diffraction line profile analysis and atomic force microscopy (AFM). Diffraction peaks representing three different types of preferred growth in HTF are analyzed, namely textures with (00λ), (223) and (203) net planes oriented parallel to the substrate. No additional line-broadening (compared to silicon powder used as standard) is observed in the case of a film prepared at high substrate temperature of 170 °C. On the other hand, considerable broadening is detected in a film with the substrate kept at room temperature. Multiple line analysis documents that the crystallite size and lattice strain for the sample is 150 nm and 3×10−4, respectively. Single line analysis performed on the other reflections reveal size-induced broadening for a crystallite size in the range 40 to 50 nm. From AFM data we obtained that the maximum roughness of the surface is about 40 nm. The results indicate that the deposition temperature significantly influences the microstructural properties and that higher substrate temperature promotes a higher mobility of the molecules on the substrate enabling growth of larger crystallites with lower strain.
Nonlinear Optical Films by Alternating Polyelectrolyte Deposition on Hydrophobic and Hydrophilic Substrates
Authors: Roberts M. Joseph 
Published: April 2011

ABSTRACTThe formation of acentric films using alternating polyelectrolyte deposition (APD) has been achieved on hydrophobic and hydrophilic glass substrates. APD is a layer-by-layer technique for the formation of polymer films by alternately immersing a substrate in aqueous solutions of a polyanion and a polycation. APD provides precise control of the overall film thickness that through automated processing may exceed a thousand layers. In this study, APD films were made of an NLO-active polycation, stilbazolium-substituted polyepichlorohydrin (SPECH), and NLO-inactive polyanions. The peak maximum UV-Visible absorbance in transmission through the films was linear as a function of the number of bilayers. Second harmonic generation (SHG) was used as a tool to indicate acentric order of polarizable sidechain chromophores within the APD films. The SHG exhibited the expected quadratic intensity increase with film thickness.
A Study of Group Velocity Dispersion of Single-Mode Optical Waveguide Utilizing Siloxane Polymer
Authors: Ueno Y. , Kaneko K. , Tanahashi S. 
Published: April 2011

ABSTRACTWe have developed a single-mode optical waveguide utilizing siloxane polymer on ceramic substrate for opto-electronic multichip modules (O/E-MCM) to operate Tera bps. In this paper, we describe group velocity dispersion for the optical waveguide utilizing siloxane polymer on ceramic substrate. The group velocity dispersion becomes 0 fs/cm·nm at around 1310 nm and 1530 nm wavelength. There is abnormal dispersion at around 1530 nm. The results showed that the group velocity dispersion of the optical waveguide was significantly related to the absorption spectrum of siloxane polymer. The group velocity dispersion of the optical waveguide is about 0.4 fs/cm·nm at 1550 nm wavelength. When a 500 femto seconds optical pulse, which has 16 nm for spectrum width, pass through the 50 mm long optical waveguide, pulse expansion is estimated 20 fs/cm·nm. This expansion of spectrum is well to distinguish femto seconds optical signals. Thus, the optical waveguide utilizing siloxane polymer is capable for femto seconds optical pulses transmission.