bluuebunny/crossref_metadata_2025_split huggingface dataset:
Investigation of Textured Back Reflectors for Microcrystalline Silicon Based Solar Cells
Authors: Kluth O. , Vetterl O. , Carius R. , Finger F. , Wieder S. , Rech B. , Wagner H. 
Published: April 2011

AbstractMicrocrystalline silicon (μc-Si:H) solar cells require an effective light trapping in the near infrared (NIR) to enhance the long wavelength spectral response. For this purpose we investigated back reflectors based on texture-etched ZnO/Ag stacks prepared on glass substrates by magnetron sputtering. With decreasing sputter pressure the resulting surface texture of the glass/Ag/ZnO substrates after etching exhibits a larger feature size and root mean square roughness. The increase in feature size corresponds to an increase of diffuse reflectivity. Applied in microcrystalline solar cells prepared by VHF plasma enhanced chemical vapour deposition (PECVD), the reflectors showing the largest feature size (prepared at the lowest possible sputter pressure) yielded the highest long wavelength spectral response. The μc-Si n-i-p cells prepared on the latter back reflector exhibited efficiencies of 6.9 % (short circuit current density jsc= 18.8 mA/cm2) and 7.5 % (jsc=25 mA/cm2) for an i-layer thickness of 1 μm and 3.5 μm, respectively.
UV Imager in TFA Technology
Authors: Motze F. , Seibel K. , Schneider B. , Hillebrand M. , Blecher F. , Lulé T. , Keller H. , Rieve P. , Wagner M. , Böhm M. 
Published: April 2011

AbstractAn image sensor with enhanced sensitivity for near ultraviolet radiation (UVA) has been fabricated in TFA (Thin Film on ASIC) technology. The device employs an amorphous silicon pin detector optimized for UV detection by carbonization and layer thickness variation. The front electrode consists of an Al grid or TCO. Measurements show a peak responsivity of 90 mAW-1 at 380 nm. The UV Imager prototype consists of 128 × 128 pixels with a size of 25 μm × 25 [tim each, fabricated in a 0.7 μm CMOS process. Global sensitivity control serves to achieve a dynamic range in excess of 80 dB. The sensor can be used in fields such as chemical, medical and astronomical applications. Furthermore, a UV monitor has been developed, suited to warn of excessive sunlight exposure, considering skin type and sun protection factor.
Directional Breakdown of Metal/a-Si:H/c-Si Heterostructures and its Application to PROMs
Authors: Zhu Hong , Kalkan Ali Kaan , Cuiffi Joseph , Fonash Stephen J 
Published: April 2011

AbstractThis paper gives the first report of a directional breakdown phenomenon present in specially constructed amorphous silicon / crystalline silicon heterojunction structures. After breakdown, the forward current can be greatly increased, but the reverse leakage current remains unchanged or even lowered. We use the Analysis of Microelectronic and Photonic Structures (AMPS) [1] device simulation tool to study this phenomenon and show that the structures can provide a new approach to producing Programmable Read Only Memory (PROM).
Why SiNx:H is the Preferred Gate Dielectric for Amorphous Si Thin Film Transistors (TFTS) and SiO2 is the Preferred Gate Dielectric for Polycrystalline Si TFTs
Authors: Lucovsky Gerald , Phillips J.C. 
Published: April 2011

ABSTRACTConstraint theory developed for bulk glasses and recently applied to thin films and single crystalline Si (C-Si) dielectric interfaces is extended in this paper to a-Si:H and polycrystalline-Si (poly-Si) dielectric interfaces in TFTs where it provides guidelines for device optimization. The constraining effects of network bonding forces are a linear function of the average bonding coordination, Nav. Nav ∼ 3 separates low-defect density networks as in Si02 (Nav =2.67), from highly-defective networks such as non-hydrogenated Si3N4 (Nay = 3.43). Nay ∼ 3 also separates device-quality from highly-defective Si-dielectric interfaces. These criteria are applied to Si-Si02 and Si-SiNx:H interfaces that are integral components of TFT devices.
Gate Current Suppressed Lateral FEAs with Integrated TFTs
Authors: Lim Moo-Sup , Park Cheol-Min , Han Min-Koo 
Published: April 2011

ABSTRACTLateral FEAs which have three terminals, stable anode current, and suppressed gate current are proposed and fabricated. In order to eliminate the path of electrons between tips and anode, the proposed FEAs are sealed by evaporation of oxide while Molybdenium in our privious work. Experimental results such as controllibility of gate electrode, a portion of the gate current for the anode current, and stability of the anode current are given. The proposed FEAs exhibit an excellent controllibility by gate electrode and stability of the emission current. The gate current of new FEAs is negligible compared with the ande current while that of the privious FEAs is about 20% of the anode current.
A Novel Two-Pass Excimer Laser Crystallization Process to Obtain Homogeneous Large Grain Polysilicon
Authors: Mariucci L. , Carluccio R. , Pecora A. , Foglietti V. , Fortunato G. , Sala D.Della 
Published: April 2011

ABSTRACTNew approach to control the lateral growth mechanism through the opportune spatial modulation of the absorbed laser energy and with a two-pass excimer laser crystallization process is presented. In the first pass, spatial modulation of the light intensity has been obtained by irradiating the sample through a patterned mask in contact with the sample. Lateral growth is triggered when the irradiated regions are fully melted and a lateral extension of the grains in excess to 1 μm has been observed for samples irradiated at RT. In order to homogeneously crystallize the sample, the film can be re-irradiated (second pass) without the mask. By using opportune energy densities it can be induced a complete melting of the residual a-Si regions (masked areas during the first pass), while partially melting the polysilicon regions (unmasked areas during the first pass). Different mask geometries have been investigated and for optimized conditions, the sample area can be fully covered with laterally grown grains. The proposed novel technique can be rather attractive for polysilicon TFT fabrication, being characterized by only a two laser-shot process and wide energy density windows.
Properties of Polysilicon films Oxidized in Inductively Coupled Plasma and its Effect on thin-Film Transistors
Authors: Choi Yong Woo , Ahn Jin Hyung , Ahn Byung Tae 
Published: April 2011

ABSTRACTWe investigated the properties of polycrystalline silicon (poly-Si) films oxidized in inductively coupled plasma (ICP) and the characteristics of poly-Si thin film transistors (TFTs) with an ICP/LPCVD gate oxide. The ICP oxidation reduced the interface traps and passivated dangling bonds by hydrogen incorporation. The ICP oxidation did not change the roughness of the Si/SiO2, while thermal oxidation increased the roughness largely. The characteristics of the TFTs with ICP/LPCVD oxide were improved due to the reduced interface trap density.
Structure and Properties of Quasi-Monocrystalline Silicon Thin-Films
Authors: Rinke Titus J. , Bergmann Ralf B. , Werner Jürgen H. 
Published: April 2011

ABSTRACTThis contribution describes the preparation of a single crystalline Si thin-film separable from a reusable Si wafer. The method relies on: i) etching of a porous silicon layer ii) high-temperature annealing and iii) transfer of the recrystallized film to a foreign substrate. As a result of the process we obtain 1 to 30 μm thick monocrystalline Si films that contain voids with a size of several 100 nm. Due to its “swiss-cheese-like” structure the material is termed as “quasi-monocrystalline Si”. Sub micrometer thin layers are almost compact, while in several micron thick films voids cause scattering of incident light. This effect increases the effective absorption coefficient by light trapping and seems promising for the application of our quasi-monocrystalline films in thin film solar cells. Quasi-monocrystalline p-type silicon reaches a hole mobility of 78 cm2/ Vs measured by room-temperature Hall-effect. High carrier mobility and adjustable optical characteristics make these films suitable for display and photovoltaic applications. Quasi-monocrystalline films are processed using conventional high-temperature Si processing; finished devices can be transferred to a foreign substrate such as glass, while the starting wafer can be reused several times.
Novel Device Concept for Voltage-Bias Controlled Color Detection in Amorphous Silicon Sensitized Cmos Cameras
Authors: Neidlinger T. , Harendt C. , Glökner J. , Schubert M. B. 
Published: April 2011

ABSTRACTWe present a novel sensor concept comprising a new contacting scheme for voltage-bias con- trolled thin film photodiode arrays on CMOS readout chips. Our unilateral contact structure greatly facilitates manufacturing of the sensor system. Moreover, the novel contacting scheme most efficiently suppresses crosstalk between neighboring pixels. The respective devices are ready for operation and testing directly after deposition of the amorphous silicon based sensor layers. No extra transparent front contact is needed, no patterning and no connection between the topmost layer of the thin film stack and the underlying readout chip. Due to the lack of a metal oxide front contact, contamination of CMOS manufacturing equipment with tin, zinc or similar materials is definitely avoided. Thus, for the first time, a sensor concept with complete CMOS process compatibility is demonstrated. Our new sensor structure allows for a considerable reduction in manufacturing cost of high performance optical detection systems. As a proof of concept, we present detailed investiga- tions on current-voltage characteristics, dynamic behavior and spectral response of 0.1-inch test structures. Down-scaling to pixel sizes in the micron range is evaluated by semi-empirical numerical modeling and proves easily feasible.
Photoluminescent Polymer Films for Display Applications
Authors: Palmans Anja , Montali Andrea , Weder Christoph , Smith Paul 
Published: April 2011

ABSTRACTNovel poly(p-phenylene ethynylene) polymers, ANT-OPPE and COU-OPPE, have been prepared, in which anthracene and coumarin sensitizer molecules are covalently attached to the conjugated polymer backbone via a flexible spacer. These polymers show efficient energy transfer from the pendent sensitizer molecule to the PPE backbone, both in dilute solution as well as in an oriented polyethylene matrix. In case of ANT-OPPE, we found that the PPE backbone adapts the orientation of the matrix and is efficiently oriented, while the anthracene moiety remains essentially isotropic, resulting in a state-of-the-art polarizing energy transfer for this system.
Optical Properties and Characterization of Eu3+ Activated Pmma:Paac Copolymer Samples: Eu Concentration Effects
Authors: F. R. Sosa , Flores M. , T. R. Rodríguez , F. A. Muñoz 
Published: April 2011

ABSTRACTSamples of Eu3+-activated PMMA:PAAc copolymers were prepared in order to investigate their spectroscopic properties. The densities, refractive indices, UV-Visible absorption and emission spectra and fluorescence decay times were obtained experimentally. These data were used in conjunction with Judd-Ofelt theory to calculate the spontaneous emission probabilities and branching ratios, as a function of the europium content. The range of the concentration was 0.1 to 2.5 % mol. Our results are combined with previous information on the optical properties of rare-earth activated polymers in order to get a better understanding of the role played by the Eu3+ ions on the polymerization process in our samples.
Photoluminescence of Poly(P-Phenylene Vinylene) Encapsulated in Mesoporous Silica
Authors: Pattantyus-Abraham Andras G. , Wolf Michael O. 
Published: April 2011

ABSTRACTThe preparation of poly(p-phenylene vinylene) (PPV) encapsulated in a mesoporous silica, MCM-41, is reported. In situ polymerization of xylylene bis(tetrahydrothiophenium chloride) yields a highly luminescent, yellow powder with a fluorescence spectrum matching that of unencapsulated PPV. Nitrogen adsorption isotherms show that the pore size of the PPV- loaded MCM-41 is significantly smaller than that of empty MCM-41 and a polymer loading of ca. 8% by weight is obtained by thermogravimetric analysis. Photoluminescence data for the encapsulated PPV are presented.
New Poly-Si TFT'S with Selectively Doped Region in The Channel
Authors: Lee Min-Cheol , Jeon Jae-hong , Yoo Juhn-suk , Park Kee-chan , Han Min-koo , Yoon Chan-Eui 
Published: April 2011

ABSTRACTWe propose new poly-Si TFT's with selectively doped region in the center of channel in order to reduce large leakage current. In proposed TFT's, the selectively doped region redistributes total induced electric field in the channel. For VGS<0, VDS> 0 in the n-channel proposed TFT's, most of the high electric field applies in the depletion regions which exist the drain/undoped region and undoped region/selectively doped region which faces to the source. Comparing with conventional TFT's, the electric field induced near the drain junction reduces to about 1/2, therefore, electron-hole pairs generated in drain junction are considerably reduced. Furthermore, the ON-current of proposed TFT's is the same or slightly lower than that of conventional ones. Consequently, the experimental data show the considerable improvement of the ON/OFF current ratio.
Back Gate Effects in N-Channel Monocrystalline Silicon Devices-on-Glass and their Suppression by Boron Ion Implantation
Authors: Baine Paul , Mitchell S.J.N , Gamble H.S , Armstrong B.M 
Published: April 2011

ABSTRACTInitial N-channel self aligned polycrystalline silicon gate transistors fabricated on 1.5μm -2μm single crystal Silicon-O-Glass(SOG) layers exhibited poor transfer characteristics. Measured threshold voltages and On/Off current ratios were in the order of -8V and 10 respectively. This is due to the presence of fixed charge at the bond interface introducing back gate effects which degrade and distort device performance. These back gate effects were suppressed by implantation of boron into the silicon substrate prior to oxidation and bonding, with energy 40keV and dose 7.4×1012cm−2. This resulted in an improvement in device performance with a threshold voltage of-0.54V. On/Off current ratio increased to 1840 and field effect mobility increased from 274cm2/Vs to 357cm2 Vs
Heteroepitaxial Growth of In203 on Ysz (100) Single Crystal Surface
Authors: Orita M. , Ohta H. , Tanji H. , Hosono H. , Kawazoe H. 
Published: April 2011

ABSTRACTIn203 films were deposited on YSZ (001) single crystal surface at 800°C at an oxygen pressure of 14 Pa by pulsed laser deposition (PLD) method. A heteroepitaxial relationship between the film and the substrate was seen in TEM photographs and X-ray diffraction measurements. The w locking curve full width of half maximum (FWHM) of the In203 (004) x-ray diffraction was 0.06°. Film conductivities were ∼10 S/cm or less, while carriers on the order of lO18/cm3 were generated.
Spin-on Polymer Gate Dielectric for High Performance Organic Thin Film Transistors
Authors: Sheraw C.D. , Gundlach D.J. , Jackson T.N. 
Published: April 2011

ABSTRACTWe have investigated the polymeric insulators benzocyclobutene (BCB), parylene C and polyimide for use as gate dielectrics in pentacene organic thin film transistors (TFTs). Atomic force microscopy (AFM) was used to examine the surface roughness of the polymeric dielectrics and the morphology of pentacene films deposited onto them. X-ray diffraction was used to examine the molecular ordering of pentacene films deposited onto the polymeric dielectrics. We find a correlation between the surface roughness of the gate dielectric and the grain size in deposited pentacene films, with smooth surfaces yielding larger, more dendritic grains. Despite significant changes in film morphology, pentacene TFTs using BCB, parylene C, or polyimide as the gate dielectric have performance comparable to devices using SiO2 as the gate dielectric. These results suggest that there is not a strong correlation between pentacene film grain size and field-effect mobility for these devices. Pentacene TFTs using BCB as the gate dielectric had field-effect mobility as high as 0.7 cm2/V-s, on/off ratio > 107, subthreshold slope less than 2 V/decade, and negative threshold voltage, making them an attractive candidate for use in organic-based large-area electronic applications on flexible substrates.
Self-Assembly Processes for Organic Led Transport Layers and Electrode Passivation
Authors: Malinsky J.E. , Li W. , Wang Q. , Cui J. , Chou H. , Marks T.J. , Jabbourt G.E. , Shaheen S.E. , Anderson J.D. , Lee P. , Richter A.G. , Kippelen B. , Dutta P. , Peyghambarian N. , Armstrong N. 
Published: April 2011

ABSTRACTThis contribution describes the use of self-limiting siloxane chemisoroption processes to self-assemble building blocks for the modification of vacuum-deposited organic LED (OLED) devices. One approach consists of the use of self-assembling OLED hole transport materials for application in hybrid self-assembled + vapor deposited two-layer devices. Another approach involves the application of self-limiting, chemisorptive self-assembly techniques to introduce thin dielectric films between the anode and hole transport layer of a vapor deposited two-layer OLED device.
Polyquinolines: Multifunctional Polymers for Electro-Optic and Light-Emitting Applications
Authors: Jen Alex K.-Y. , Ma Hong 
Published: April 2011

ABSTRACTA versatile, and generally applicable modular approach for making second-order nonlinear optical (NLO) side-chain aromatic polyquinolines has been developed. This approach emphasizes the ease of incorporating NLO chromophores onto the pendent phenyl moieties of parent polyquinolines at the final stage via mild Mitsunobu reaction. This method provides the synthesis of polyquinolines with a broad variation of the polymer backbones and great flexibility in the selection of NLO chromophores. These side-chain NLO polyquinolines demonstrate high electro-optic (E-O) activity (up to 35 pm/V at 830 nm and 22 pm/V at 1300 nm, respectively) and a good combination of thermal, optical, electrical and mechanical properties.Comparatively, two new electroluminescent (EL) polyquinolines have been prepared via the Friedlander condensation and nucleophilic reaction. The resulting polymers contain a bipolar property with both an efficient hole-transporting moiety, tetraphenyldiaminobiphenyl (TPD), and an electron affinitive light-emitting moiety, bis-quinoline. In addition, they possess high thermal stability, excellent electrochemical reversibility, good thin film-forming ability, and bright light-emitting property. Electrical characterization of two-layer diode devices based on the configurations of ITO/CuPc/TPD-PQ or TPD-PQE/Al showed excellent electroluminescence performance (a rectification ratio greater than 105 and a low turn-on voltage of less than 4 V).
Cathode Lifetime Issues in Field Emission Displays
Authors: Reuss Robert H. , Chalamala Babu R. 
Published: April 2011

ABSTRACTField emission displays are currently undergoing rapid transition from laboratory prototypes into commercial display components. Display lifetime and reliability are critical issues that will determine success of these displays in the marketplace. In this paper, we will summarize issues affecting field emission display lifetime and a roadmap for creating long life field emission display devices.
Long-Term Degradation Mechanism of Organic Light Emitting Devices Based on Small Molecules
Authors: Aziz Hany , Popovic Zoran D. , Hu Nan-Xing , Hor Ah-Mee , Xu Gu 
Published: April 2011

ABSTRACTThe intrinsic degradation of tris(8-hydroxyquinoline) aluminum (AlQ3)-based organic light emitting devices, that leads to the long-term decrease in the electroluminescence efficiency of the devices operated under constant current conditions, is studied. The injection of holes in A1Q3 is found to be the main factor responsible for device degradation. OLEDs with dual HTLs in different arrangements are also presented to demonstrate the proposed degradation mechanism. The role of various approaches to increase OLED lifetime, such as, doping the hole transport layer, introducing a buffer layer at the hole-injecting contact, or using a mixed emitting layer of hole and electron transporting molecules, is explained.
Field Emission Energy Distribution and Current-Voltage Characteristics Using Single Tip Gated Diodes
Authors: Bernhard John M , Rouse Ambrosio A. , Sosa Edward D. , Gnade Bruce E. , Golden David E. , Chalamala Babu R. , Aggarwal Sanjeev , Ramesh R. 
Published: April 2011

ABSTRACTField emission current-voltage characteristics and simultaneous field emission electron energy distributions have been measured using single tip gate diodes. An energy distribution is generated at each step of a current-voltage characteristic using a compact low-cost simulated hemispherical energy analyzer. A PC programmed with graphics-based data acquisition software is used for data acquisition and control. The PC is connected to a CAMAC crate and a picoammeter through a GPIB interface. The picoammeter measures the current leaving the tip and the field emission electrons are energy analyzed, detected and processed in the CAMAC crate. The CAMAC crate also sends control voltages. to the gate anode and the energy analyzer. This apparatus was used to measure tip work functions and Fowler-Nordheim tip shape parameters for Mo and IrO2 field emission tips. Work function measurements from field emission tips are compared to photoelectric work function measurements from flat surfaces.
Selective Area Laser Induced Deposition of Metal Boride Thin Films
Authors: Zhong Z.C. , Holmes V. , Dowben P.A. , Sellmyer D.J. 
Published: April 2011

ABSTRACTWe have developed a novel technique for the selective area deposition of rare earth hexaborides: laser-induced solution deposition (LISD). This technique is both simple and efficient and combines many advantages of both chemical vapor deposition and electrolytic deposition. The results of LISD deposition show that the polycrystalline thin films of rare earth hexaborides and sub-borides such as MB6, MB4, and MB2 (M = Gd, La) are formed through the light initiated chemical reaction of nido-decaborane (B10H14) and rare earth chloride in solution. These films grow with a strong texture growth axis and morphology that is dependent both on the selection of solvents and laser wavelengths and power used in LISD.
Lifetime and Stability of Carbon Cold Cathodes
Authors: Fink R. L. , Thuesen L. H. , Tolt Z. Li , Yaniv Zvi , Marrese Colleen M. 
Published: April 2011

ABSTRACTWe present the results of tests measuring the life of carbon cold cathodes and determining what conditions limit the life of the cathode. Cathode life and stability are important for a broad range of applications, including displays, electron sources for satellite thrusters, x-ray tubes and microwave devices. Cathodes were tested in vacuum chambers using different gas environments as well as in sealed and gettered glass envelopes. We measured emission current half-lives of 10,000 - 20,000 hours or more in sealed display devices, depending on operating conditions. The presence of a significant oxygen or water partial pressure degrades the life of the cathode. After removing the gases the decay rate was restored to near the original value. A similar partial pressure of hydrogen gas has little or no effect on the life of the cathode. Initial results of operation in a xenon environment indicate carbon cold cathodes are much more robust compared to microtip cathodes. These results will be discussed with respect to the various applications considered for carbon cold cathodes.