bluuebunny/crossref_metadata_2025_split huggingface dataset:
DC to 65 GHz Wide Bandwidth InGaAs Photodiodes and Photoreceivers
Authors: Joshi Abhay M. 
Published: April 2011

AbstractWe have developed 65 GHz Wide Bandwidth InGaAs Photodiodes and Photoreceivers for optical fiber driven telecommunication applications. The Photodiode operates at a nominal reverse bias of -3V and has a minimum responsivity of 0.5 A/W at 1300 and 1550 nm wavelength. The Ripple Factor is less than ± dB for a wide band of frequencies, DC to 50 GHz. The salient feature of the PIN is an on-chip co-planar waveguide output for proper impedance matching. We have also designed Ultra Wide Bandwidth Amplifiers using InGaAs p-HEMT technology and monolithically integrated them with InGaAs Photodiodes. These Opto-electronic Integrated Circuits (OEICs) which combine optical, microwave, and digital functions on the same chip is a technology that has significant potential for commercial applications such as ethernet fiber local area networks and optical communications systems (Synchronized Optical Network SONET, ISDN, telephony and digital CATV). Important inter-service military applications are optically fed phased array systems and optically controlled microwave networks for airborne and spaceborne systems.
Bandgap Variation and Miscibility Gaps of Thallium-Based Pseudo-Binary Alloys
Authors: Chen A.-B. , Piao J. 
Published: April 2011

AbstractTo stimulate further research on the TI-based semiconductor alloys for long-wave infrared (LWIR) application, we carried out detailed calculations for the variation of band gaps versus lattice constants and the alloy miscibility gaps of cation-substituted pseudo-binary alloys. These results are used to identify promising TI-based LWIR alloys and the lattice-matched non-TI bearing alloys for possible substrates and passivation caps. Although all the six Tl-bearing pseudo-binary alloys studied can have a 0.1 eV band gap, none of these systems are lattice matched to a pure III-V compound. Five of these six alloys can have a non-TI-bearing lattice-matched ternary alloy as the substrate, but only two do not have a serious problem with the miscibility gap. When further considering the difficulty of incorporating TI with a large concentration, the only promising LWIR pseudo-binary alloy left is In1−xTlxAs with x≍0. 16.
Growth of InSb on GaAs Substrates Using InAlSb Buffers for Magnetic Field Sensor Applications
Authors: Biefeld R. M. , Phillips J. D. 
Published: April 2011

AbstractWe report the growth of InSb on GaAs using InAISb buffers of high interest for magnetic field sensors. We have grown samples by metal-organic chemical vapor deposition consisting of ∼0.55µm thick InSb layers with resistive InAlSb buffers on GaAs substrates with measured electron mobilities of ∼40,000 cm2/V.s. We have investigated the In1−xAlxSb buffers for compositions x≤0.22 and have found that the best results are obtained near x=0.12 due to the tradeoff of buffer layer bandgap and lattice mismatch.
Surface Microchemical Reactions during Hydrogenated Silicon Growth Studied by In-situ ESR Technique
Authors: Yamasaki Satoshi 
Published: April 2011

ABSTRACTThe in-situ ESR technique is applied to a plasma-enhanced chemical vapor deposition (PECVD) system in order to investigate the surface microchemical reactions during the growth of hydrogenated amorphous silicon (a-Si:H) and plasma treatments of H2 and Ar gases on a- Si:H. The growth model of a-Si:H and the role of H atoms on a-Si:H films are discussed using the experimental results. The recent results on the dynamic surface reactions of crystalline silicon with oxygen molecules in an ultra-high-vacuum ESR system are introduced.
Effects of buried insulator-sensor interface on the lateral conduction of high fill factor aSi:H imagers
Authors: Mulato M. , Lemmi F. , Ready S. E. , Lu J. P. , Van Schuylenbergh K. , Street R. A. , Ho J. , Lau R. , Boyce J. B. 
Published: April 2011

ABSTRACTThe pixel cross-talk is investigated in two-dimensional amorphous silicon (a-Si:H) imager arrays based on the new high fill factor design. In this configuration a continuous a-Si:H sensor extends over the whole surface of the imager, and a buried insulator material with low dielectric constant is used to separate the sensor from the underlying active matrix readout circuit. We find that the lateral conduction between neighboring pixels is mainly determined by the quality of the buried insulator-sensor interface, rather than the specific buried material itself. Minimum cross-talk values below 1% are obtained for different insulator materials including silicon oxynitride and thicker polymer based resins. The quality of this interface also affects trapping and recombination of the photogenerated carriers, influencing important imager properties such as sensitivity and image lag.
a-SiN:H Thin Film Diode for Digital Radiography
Authors: Popov I.A. , Doorselaer G. Van , Calster A. Van , Smet H. De , Baets J. De , Callens F. , Boesman E. 
Published: April 2011

ABSTRACTRecent developments in the area of cost effective 2D direct x-ray sensor arrays on the base of a-SiN:H back-to-back Schottky diodes and no switching devices per pixel are presented. Discussion focuses on two major aspects: (i) x-ray sensitivity of the sensor itself and possibility of its improvement; (ii) the overall performance of the sensor array.
Investigation of Crystalline Silicon Surface Treatments in Amorphous – Crystalline Heterojunction Via Capacitance Measurements
Authors: Tucci M. , Rosa R. De , Roca F. , Caputo D. , Palma F. 
Published: April 2011

ABSTRACTIn this work we investigate the density of states at amorphous-crystalline silicon interface that play the key role in the heterostructure solar cell application. In particular we analyzed the defect density arising from plasma treatment of the crystalline surface. This process is useful to clean the crystalline surface, but greatly influenced the electrical properties of the device. We used low temperature (20K-300K) capacitance measurement performed in a wide range of frequency of signal probe (1Hz-10kHz). Differences in the capacitance profile between samples with various plasma dry treatments indicate different defect density profile at interface. With the aid of a finite difference model of the capacitance as a function of temperature and frequency we extract information from the measurements about the defect energy distribution at interface. As a result, the density and the nature of defects at interface will be correlated to the technological parameters as: wafer cleaning procedure, hydrogen plasma treatment, type and concentration of dopants at interface.
Microstructures of Microcrystalline Silicon Solar Cells Prepared by Very High Frequency Glow-Discharge
Authors: Dubail J. , Vallat-Sauvain E. , Meier J. , Dubail S. , Shah A. 
Published: April 2011

ABSTRACTThe microstructure of two different νc-Si:H solar cells was studied by Transmission Electron Microcopy (TEM). At the micrometer scale, a difference in the grain structure is observed close to the ZnO substrate: cracks are found in the cell deposited with the higher silane concentration. Surprisingly, the cell with the cracks close to the transparent conductive oxide shows the largest VOC (530 mV) and FF (68%). These first studies reveal that microstructures of fully microcrystalline silicon devices may show a quite large variation with corresponding effects in solar cell performance.
Hydrogenated Amorphous Silicon Photodiode Technology for Advanced CMOS Active Pixel Sensor Imagers
Authors: Theil Jeremy A. , Cao Min , Kooi Gerrit , Ray Gary W. , Greene Wayne , Lin Jane , Budrys AJ , Yoon Uija 
Published: April 2011

ABSTRACTAmorphous silicon photodiode technology is a very attractive option for image array integrated circuits because it enables large die-size reduction and higher light collection efficiency than c-Si arrays. We have developed a photodiode array technology that is fully compatible with a 0.35νm CMOS process to produce image sensors arrays with 10-bit dynamic range that are 30% smaller than comparable c-Si photodiode arrays. The VGA (640x480), array demonstrated here uses common intrinsic and p-type contact layers, and makes reliable contact to those layers by use of a monolithic transparent conductor strap tied to vias in the interconnect. The work presented here will discuss performance issues and solutions that lend themselves to cost-effective high-volume manufacturing. The various methods of interconnection of the diode to the array and their advantages will be presented. The photodiode dark leakage current density is about 80 pA/cm2, and its absolute quantum efficiency peaks about 85% at 550 nm. The effect of doped layer thickness and concentration on quantum efficiency, and the effect of a-Si:H defect concentration on diode performance will be discussed.
Hydrogenated Microcrystalline Silicon: From Material to Solar Cells
Authors: Wyrsch N. , Droz C. , Feitknecht L. , Goerlitzer M. , Kroll U. , Meier J. , Torres P. , VallatSauvain E. , Shah A. , Vanecek M. 
Published: April 2011

ABSTRACTUndoped hydrogenated microcrystalline silicon (νc-Si:H) layers and solar cells have been deposited by plasma-enhanced chemical vapour at low temperature and at different values of VHF plasma power and silane to hydrogen dilution ratios. Transport and defect density measurements on layers suggest that structural properties (e.g. crystallite shape and size) only marginally influence the electronic transport properties. The latter are influenced strongly by the Fermi level, which depends on the oxygen impurity content. Furthermore, they are best described by the quality parameter ν0τ0 (deduced from photoconductivity and ambipolar diffusion length). Cell efficiency correlates better with νoτ0 than with the defect density as determined from subbandgap absorption. Anisotropy of the transport properties in some νc-Si:H is also demonstrated but does not seem to play a major role in νc-Si:H cells deposited at high rates under VHF glow discharge conditions.
Improved Crystallinity of Microcrystalline Silicon Films Using Deuterium Dilution
Authors: Suzuki Susumu , Kondo Michio , Matsuda Akihisa 
Published: April 2011

ABSTRACTDeuterium dilution instead of hydrogen has been studied in microcrystalline silicon growth using plasma enhanced chemical vapor deposition with monosilane. It was found that the crystallinity for D2 dilution is significantly improved as compared to that for H2 dilution at the same growth rate. Optical emission spectroscopy measurement shows that the electron temperature of SiH4 + D2 plasma is lower than that of SiH4 + H2, indicating that the bombarding ion energy is reduced for D2 dilution. It was also found that the H-D exchange reaction on the surface has a certain threshold number of events and that microcrystalline formation occurs only above the threshold. The role of atomic hydrogen originating from a diluent in crystal formation is discussed.
Ultrafast Dynamics of Photoexcitations in HWCVD Hydrogenated Amorphous Silicon Alloys
Authors: Young J.E. , Nelson B.P. , Dexheimer S.L. 
Published: April 2011

ABSTRACTWe present femtosecond studies of carrier dynamics in hydrogenated amorphous silicon-germanium alloys grown by the recently developed hot-wire assisted chemical vapor deposition (HWCVD) technique, which is promising for producing high-quality device-grade materials. We have used wavelength-resolved femtosecond pump-probe techniques, in which an intense pump pulse excites carriers in the sample and a time-delayed probe pulse measures the resulting change in optical properties as a function of time delay following the pump pulse, to study the dynamics of photoexcitations in these materials. Femtosecond dynamics measurements have been carried out on thin film samples under experimental conditions with varying sensitivity to carriers in extended states or in band tail states. The relaxation dynamics of carriers associated with extended states show a strong dependence on excitation density and follow a bimolecular recombination law, consistent with a number of earlier studies on related amorphous materials. In contrast, measurements involving carriers excited directly into band tail states reveal significantly altered dynamics, characterized by a marked deviation from simple bimolecular recombination at short times.
Novel Micro-Photodiodes for Retina Stimulation
Authors: Rojahn M. , Schubert M.B. 
Published: April 2011

ABSTRACTWe present a new design of micro-photodiodes for in-vitro tests to electrically stimulate the ganglion cells of chicken and rat retinae upon light exposure of the photodiodes. Based on amorphous silicon, our laterally series connected double-stacked micro-photodiodes provide an open circuit voltage of 2.3 volts. Photolithographic steps as well as etching procedures for patterning the back contact, the amorphous silicon layers and the front contact are described. We analyse current- voltage-measurements performed with direct contact of the metal needles of a micro-positioning system to the device's electrodes. In order to test the performance of an individual micro-photodiode in an electrolyte environment, the stimulation electrode of the device is also contacted with a micro-droplet of buffer solution. Further improvement is needed, mainly addressing the problem of long-term stability of the device in electrolyte environments.
Ftir Spectroscopy and Spectroscopic Ellipsometry Study of Nanocrystalline Layers Formed by High-Dose Hydrogen and Deuterium Implantation of Silicon
Authors: Safronov L.N. , Spesivtsev E.V. , Popov V.P. , Antonova I.V. , Gutakovskii A.K. , Obodnikov V.I. 
Published: April 2011

ABSTRACTStructural study of a-Si layers formed by high fluence hydrogen or deuterium implantation (up to 5×1017 cm−2) using high current beams with means of current up 40 mA/cm2 was carried out in the present work. The Si:H(D) silicon films were characterized using FTIR spectroscopy, spectroscopic ellipsometry, transmission electron microscopy and secondary ion mass spectrometry. Hydrogen solubility in crystalline silicon is low but ion implantation allows one to introduce hydrogen atoms in the concentration of 1022cm−3 or even more in thin silicon layer. High defect concentration in combination with high hydrogen activity causes the formation of mixed amorphous and crystalline phases with structure similar to silicon produced PECVD or laser ablation. The transformation of optical properties of this film during annealing in temperature range of 200-1050°C was investigated. The changes in optical characteristics and number of Si-H or Si-D bonds in the spectra of IR absorption is correlated with increase in crystalline volume of silicon with a temperature.
Floating Body Induced Transient Characteristics in Polycrystalline Silicon TFTs
Authors: Xu Y.Z. , Clough F.J. , Narayanan E.M.S. , Cross R. 
Published: April 2011

ABSTRACTThe floating body induced transient characteristics in polycrystalline silicon TFTs is reported. An obvious current surge, arising from the floating body effect, is observed. Using a 2D numerical simulator and comparisons to SIMOX FETs, the insight into the mechanisms governing the experimentally observed switching behavior of poly-Si devices is obtained. It is found that the defect states in poly-Si cause the current surge and exert an effect equivalent to doping in SIMOX FETs.
Integration and Characterization of Low Carbon Content SiOxCyHzLow κ Materials for < 0.18μm[ Dual Damascene Application
Authors: Lee Ju-Hyung , Chopra Nasreen , Ma Jim , Lu Yung-Cheng , Huang Tzu-Fang , Willecke Ralf , Yau Wai-Fan , Cheung David , Yieh Ellie 
Published: April 2011

AbstractA CVD-based low κ film was evaluated for inter-metal dielectric in < 0.18 [.proportional]m generation devices. The film was deposited by conventional rf PECVD method using organosilane compound and oxygen. The measured dielectric constant of the film was 2.7∼2.75. The κ value of the film was stable over several weeks and the moisture absorption was minimal. The chemical composition was in the form of SiOxCyHz, where the carbon content was less than 5 atomic %. Blanket film integration study was conducted to find out the manufacturing compatibility. The largest increase in κ value occurred during etching and ashing steps. However, SIMS compositional analysis revealed that the damage from these steps were limited to within top 300 Å, and the initial low κ value was recovered after the top damaged layer was removed by CMP. The final integrated dielectric constant was less than 3.0. The film density was measured as 1.4, compared to 2.3 g/cm3of conventional SiO2. The low density of the film resulted from the termination of SiO2network structures by Si-CH3and Si-H.
Deposition of Smooth Thin Cu Films in Deep Submicron Trench by Plasma CVD Reactor with H Atom Source
Authors: Shiratani Masaharu , Jin Hong Jie , Nakatake Yasuhiro , Koga Kazunori , Kinoshita Toshio , Watanabe Yukio 
Published: April 2011

AbstractEffects of H irradiation on purifying Cu films and improving their surface roughness as well as size and orientation of Cu grains in the films have been examined using a newly developed plasma CVD reactor equipped with an H atom source, in which Cu(hfac)2 is supplied as the source material. The H irradiation is effective in purifying the Cu films, increasing the grain size, and reducing the surface roughness, while it has no effect on the grain orientation. The decrease in dissociation degree of material gas leads to reduction of the surface reaction probability of Cu- containing radicals, which is important to realize conformal deposition in fine trenches. Using the control of dissociation degree of material gas independent of H irradiation, we have demonstrated conformal deposition of smooth Cu films in the trench using the developed plasma CVD reactor.
Kinetics Model for the Self-Encapsulation of Ag/Al Bilayers
Authors: Wang Y. , Alford T. L. , Mayer J. W. 
Published: April 2011

AbstractA model is proposed to describe the temperature dependence of the aluminum oxynitride (AlxOyNz) diffusion barrier formation during a silver self-encapsulation process. These barrier layers form in the temperature range of 500-725 °C during anneals of the Ag/Al bilayers on oxidized Si substrates in an ammonia ambient. Experimental results show that temperature has a significant effect on the kinetics of this process. In this investigation, the diffusion of Al atoms through the Ag layers during self-encapsulation process is modeled using an analytical solution to a modified diffusion equation. This model shows that higher anneal temperatures will minimize the retardation effect byi) reducing the chemical affinity between Al and Ag atoms, andii) allowing more Al atoms to surmount the interfacial energy barrier between the metal layer (Ag) and the newly formed AlxOyNzdiffusion barriers. The theoretical predictions on the amount of segregated Al atom correlate well with experimental results from Rutherford backscattering spectrometry. This model in addition confirms the self-passivation characteristics of AlxOyNzdiffusion barriers formed by Ag/Al bilayers annealed between 500∼725 °C.
Real Time Substrate Temperature Control by Emissivity Compensated Pyrometry During InxGa1−xAs1−y/InP Growth on Production Scale Rotating Disc MOVPE Reactors
Authors: Ramer J. , Patel B. , Patel A. , Boguslavskiy V. , Gurary A. 
Published: April 2011

AbstractLong term control of the substrate temperature in production scale MOVPE reactors is the most significant issue effecting yields in highly temperature sensitive epitaxial growth processes. Recent advances in non-contact emissivity compensated pyrometry wafer temperature measurements have allowed the development of a novel multi-wafer (6×2”) rotating disc MOVPE reactor with real time substrate temperature control. With this system, the substrate temperature is a directly controlled process variable, in contrast to some conventional MOVPE systems which use thermocouples for process temperature control. In addition to controlling the absolute temperature of the substrates, the temperature uniformity across the substrates is also controlled by pyrometry. This provides for a uniform temperature (+/- 1.5 °C) across the substrates independent of the flow conditions within the reactor. Thermal uniformity is also automatically maintained during temperature ramping. The highly temperature sensitive quaternary InGaAsP is used as an epitaxial metric for this novel control system, to demonstrate the advantages of pyrometry controlled substrate temperature. These advantages include: excellent long term substrate temperature reproducibility; invariance of substrate temperature to substrate doping level; the ability to transfer processes from one type of wafer carrier or reactor to another with minimal adjustment.
Atomistic Modeling of Ultrathin Fe Films on Cu (111)
Authors: Rakotomahevitra A. , Wille L. T. , Rakotomalala M. S. 
Published: April 2011

AbstractWe have used the embedded-atom method (EAM) to perform molecular-dynamics (MD) simulations of iron films grown on Cu (111). The iron atoms were randomly deposited, one at a time, above the surface just within the force range of the nearest surface atom. The growth mode is discussed by following the iron film coverage for an incident-atom energy ranged from 0.5eV to 15eV. A transition from island to layer by layer growth is observed as a function of incident energy. The effect of deposition rate is also studied.
A Hollow-Cathode Transient Plasma Process for Thin Film Growth
Authors: Witanachchi S. , Mahawela P. , Mukherjee P. 
Published: April 2011

AbstractWe have developed a vapor deposition method that produces a highly ionized transient plasma plume of metallic species in the presence of a low-pressure inert or reactive gas glow discharge. In this process, a transient electrical discharge is formed in a hollow-cathode by a pulse-forming network (PFN) which is triggered by a pulsed CO2 laser. Current pulses with peak currents of 100 kA and pulse widths of about 20 ms have been produced by the PFN. The effect of the PFN power input and the ambient gas pressure on the evaporated material yield is presented. These experiments also showed a higher evaporation rate of carbon in a nitrogen ambient than in an Ar ambient. Carbon films, with rates of deposition exceeding 18A per pulse that are uniform over a large area, have been deposited. The ionic content of the plasma, spatial distribution of ions, and plume expansion dynamics have been investigated by time-of-flight ion probe measurements and optical emission spectroscopy and are presented.
Diamond Synthesis with Completely Closed Eacvd Method
Authors: Kato Takashi , Nishida Masahiro , Takagi Yoshiki 
Published: April 2011

AbstractMany experimental results were reported of CVD diamond synthesis with so called flow systems, which need introduction of source gas and evacuation of reactant gas. For few years, we had been concentrated of development completely closed diamond synthesizing system aimed for microgravity experiments. Recently we started the new method with graphite as a carbon source. With this method, completely closed system is successfully performed. Graphite rods are used as solid carbon source and at the same time as thermal energy source. Silicon (100) wafer was used for substrates. Hydrogen gas was introduced into the reaction chamber with the suitable initial pressure. and controlled with Joule heating. The deposits were identified with SEM and Raman spectrometry. We tried to synthesize diamond on Si substrate under the conditions of forward bias where the substrate is held at a positive potential relative to the graphite rod. And also we tried the experiment under the reverse bias.