bluuebunny/crossref_metadata_2025_split huggingface dataset:
Quantum Well Intermixing Using Sputtered Silica for Photonic Integrated Circuits Operating Around 1550 nm
Authors: Marsh John H. , Catrina Bryce A. , Kowalski Olek P. , McDougall Stewart D. , Ke Maolong , Qiu Bocang , Qian Yahong 
Published: April 2011

AbstractA novel technique for quantum-well intermixing has been developed using sputtered silica. The technique relies on the generation of point defects via plasma induced damage during the deposition of the sputtered silica. The presence of the defects before annealing allows the intermixing to take place at lower annealing temperatures (>200 C) than those needed for conventional impurity free vacancy disordering. The low annealing temperature has allowed the technique to be applied to InP based quantum well systems such as InGaAs/InGaAsP and InGaAs/InGaAlAs, and provides a simple and reliable process for the fabrication of both wavelength tuned lasers and monolithically integrated devices operating around 1550 nm.Wavelength tuned broad area oxide stripe lasers have been demonstrated in InGaAs-InAlGaAs and InGaAs-InGaAsP quantum wells. Oxide stripe lasers with integrated intermixed slab waveguides have enabled the production of a narrow (3 degrees), single lobed far field pattern in InGaAs-InAlGaAs devices. Extended cavity ridge waveguide lasers operating around 1550 nm have been demonstrated with low loss (alpha = 4.1/cm) waveguides, the loss beinglimited by free carrier absorption in the waveguide cladding layers. Ridge waveguide, deeply etched surface grating DBR lasers were fabricated both with and without intermixing the grating section. Measurements show that a significant improvement in performance is obtained from the DBR lasers when the grating section is intermixed.The intermixing technique has been further developed in order to realise 3 bandgaps on a chip in a single annealing step for the integration of amplifiers, passive waveguides and bandgap tuned electro-absorption modulators. Modulation depths of 25 dB were measured from the modulators.The results illustrate that the technique can routinely be used to fabricate low-loss optical interconnects and bandgap tuned devices, offering a very promising route toward photonic integration.
Advanced GaSb/InGaAsSb/AlGaAsSb 2-2.4µm Photovoltaic Detectors
Authors: Piotrowski T.T. , Piotrowska A. , Kaminska E. , Golaszewska K. , Papis E , Piskorski M , Jung W , Katcki J , Kudla A. , Adamczewska J. , Piotrowski J. , Nowak Z. , Orman Z. , Pawluczyk J. 
Published: April 2011

AbstractThis paper reports on the design and fabrication of GaSb/n-InxGal1−xAsySb1−y/p-AlxGal−xAsySb1−y heterojuction photodetectors operating in the 2 - 2.4 µm wavelength region. Device structures were grown by LPE and fabricated as mesa-type diodes by RIE etching in CC14/H2 plasma. For mesa passivation a surface treatment in (NH42S water solution was carried out. The photodiodes structures are characterized by differential resistance RoA=400 ωcm2. Measured detectivity is in the range 3.1010 - 2. 1011 cmHz1/2/W, in dependence on the active area and cutoff wavelength.
Model for Staebler-Wronski Degradation Deduced from Long-Term, Controlled Light-Soaking Experiments
Authors: Roedern Bolko von , del Cueto Joseph A. 
Published: April 2011

ABSTRACTLong-term light-soaking experiments of amorphous silicon photovoltaic modules have now established that stabilization of the degradation occurs at levels that depend significantly on the operating conditions, as well as on the operating history of the modules. We suggest that stabilization occurs because of the introduction of degradation mechanisms with different time constants and annealing activation energies, depending on the exposure conditions. Stabilization will occur once a sufficient accumulation of different degradation mechanisms occurs. We find that operating module temperature during light-soaking is the most important parameter for determining stabilized performance. Next in importance is the exposure history of the device. The precise value of the light intensity seems least important in determining the stabilized efficiency, as long as its level is a significant fraction of 1-sun.
Colour Characterisation of a-Si:H-Based Three-Terminal Three-Channel Detector
Authors: Krĉ Janez , Topiĉ Marko , Smole Franc , Knipp Dietmar , Stiebig Helmut 
Published: April 2011

ABSTRACTColour characterisation of a three-terminal three-channel colour detector in the assembly glass/TCO1/PI1NI2P/TCO2/PI3N/Al is performed, using a method of polynomial regression. The metameric errors of the detector calculated and investigated for different orders of polynomial colour correction are presented and discussed. The benefits of the first order colour correction are shown and graphically illustrated. The final transformation matrix for the first order colour correction and conversion to the output R, G and B signals is given. At the end, a demonstrational application with the a-Si:H-based detector and corresponding read-out and colour correction electronics is presented.
Carrier Transport and Photogeneration in Amorphous Silicon / Crystalline Silicon Heterojunctions with i/n and p/n Interfaces
Authors: Vygranenko Yu. , Fernandes M. , Nunes Carvalho C. , Lavareda G. , Louro P. , Amaral A. , Schwarz R. , Vieira M. 
Published: April 2011

ABSTRACTAmorphous hydrogenated silicon films deposited by Plasma Enhanced Chemical Vapour Deposition (PE-CVD) using standard rf-glow discharge at 13.56 MHz were used to produce amorphous silicon heterostructures. Junction properties were studied from current-voltage (IV), capacitance-voltage (C-V) and spectral response measurements. The photosensitivity of these structures was investigated for different amorphous film thicknesses and different applied bias voltages. It was shown that the output device characteristics could be improved by plasma hydrogen treatment before the deposition of the amorphous layer. The results show that ITO/a-Si:H/c-Si structures present high internal gain in the visible infra-red region and high collection efficiency in the blue range. They can be used as visible/near-IR photodiodes or for current amplifications proposes.
Comparison of low temperature growth of Si thin films on amorphous substrates by MBE and PECVD methods
Authors: Selvan J. A. Anna , Grützmacher D. , Müller E. , Rebien M. , Kummer M. , Känel H. von , Gobrecht J. 
Published: April 2011

ABSTRACTLow temperature growth of thin crystalline Si films on amorphous glass substrates by Molecular Beam Epitaxy (MBE) as well as by two different plasma enhanced chemical vapour deposition (PECVD) systems both using a DC plasma was carried out and the mictrostructural properties were analysed. In particular, the control over the texture along [220] orientation and the resulting columnar nature of the films were studied. The TEM cross section of Si films grown by MBE shows grains with an average width of 750 nm and a length of 3 microns. Using the low energy PECVD (LEPECVD) technique microcrystalline Si films were obtained with a growth rate of up to 35Å/sec. For high quality Si films with larger grains one may grow Si films by MBE whereas for Si films with passivated grain boundaries and for increased deposition rate, it is preferred to grow Si films by the newly developed methods of DC-PECVD.
Spectroscopic Ellipsometry for the Characterization of the Morphology of Ultra-thin Thermal CVD Amorphous and Nanocrystalline Silicon Thin Films
Authors: Hazra Sukti , Yamanaka Mitsuyuki , Sakata Isao , Tsutsumi Toshiyuki , Maeda Tatsuro , Taguchi Hirohisa , Suzuki Eiichi 
Published: April 2011

ABSTRACTUltra-thin hydrogenated amorphous silicon thin films have been deposited by thermal chemical vapor deposition (CVD) to prepare smooth top surface of the films avoiding the ion bombardment. Rapid thermal oxidation of thermal CVD a-Si:H results in nanocrystalline dots in the ultra-thin silicon films. Spectroscopic ellipsometry (SE) and high resolution transmission electron microscopy (TEM) have been used to investigate the optical and structural properties of both ultra-thin a-Si:H and nanocrystalline silicon films. To analyze the ellipsometric data of ultra-thin a-Si:H films, a new parameterization i.e., the combination of Sellmeier law and four Lorentz peaks, has been successfully introduced. Width of the Lorentz peaks are directly related with the change of optical functions with the thickness of a-Si:H films. It has been certified that the dense Si matrix with smaller degree of disorder is formed when the thickness exceeds 8nm and the films with the thickness of less than 3.8 nm becomes voided. To interpret the ellipsometric data for nanocrystalline silicon films, three layer model (SiO2, poly-Si+a-Si+void and SiO2) has been adapted. It is inferred from SE and TEM analyses that the size and the density of nanocrystalline dots can be controlled by the morphology of initial ultra-thin a-Si:H films and RTO conditions.
Improved High Resolution Post-Transit Spectroscopy for Determining the Density of States in Amorphous Semiconductors
Authors: Main Charlie , Reynolds Steve , Badran Rashad I. , Marshall Joe M. 
Published: April 2011

ABSTRACTWe show that the analysis of post-transit photocurrent i(t) in a multi-trapping context to determine the density of trapping states g(E) is capable of resolving features less than kT in width. A commonly used method uses a Laplace inversion of i(t) data giving the well-known result g(E) ∼ t i(t) but employs a delta function approximation for trap release times, which results in loss of energy resolution. We show that it is possible to retain the exponential distribution function for trap release time and solve the multi-trapping rate equations directly, giving significantly improved resolution. The analysis is performed on computer generated post-transit data for distributed and discrete traps, and compared with the earlier method and other related Fourier transform methods for determining g(E). In addition, the versatility of the new method in handling cases with either distributed traps or with discrete traps means that it can be applied to disordered materials or to crystalline materials with well-defined defect levels.
Influence of Mechanical Stress on The Electrical Performance of Polycrystalline-Silicon Resistors
Authors: Nakabayashi M. , Ohyama H. , Simoen E. , Ikegami M. , Claeys C. , Kobayashi K. , Yoneoka M. , Takami Y. , Sunaga H. , Takizawa H. 
Published: April 2011

ABSTRACTResults are presented of a study on the mechanical stress dependence of the resistance of polycrystalline silicon (Poly-Si) films, doped with different atomic species. Two types of Poly-Si film implanted with boron and phosphorus ions were studied, namely, B-doped films of 400 nm and P-doped layers of 250 nm thickness, which were deposited by LPCVD at 620 °C on thermally oxidized silicon wafers. Film doping was done by ion implantation at 50 keV, with a dose of boron and phosphorus of 2 × 1014 and 5.3 × 1014 cm−2, respectively. The Poly-Si films were annealed in a H2 ambient at 1000 °C for 20 min to activate the implanted atoms. A controlled amount of external stress was applied to the silicon wafers in order to study the impact on the electrical performance of the implanted Poly-Si resistors. The resistance of the B-doped Poly-Si films is shown to increase by the mechanical stress, while the resistance of the P-implanted Poly-Si films remained unchanged. It is concluded that this difference is related to the structural differences between Poly-Si films implanted with boron and phosphorus, respectively.
Temperature Dependence of the Photoinduced Degradation and Annealing in a-Si:H
Authors: Schultz Niko , Taylor P. Craig 
Published: April 2011

ABSTRACTWe investigated the temperature dependence of the production and annealing kinetics of the light induced defect states in a:Si:H by electron spin resonance (ESR). At low temperatures (T ∼ 25 K) the silicon dangling bond production is about half as efficient as it is at 300 K. Defects, which are created below about 100 K, almost entirely anneal at room temperature. A sample of a-Si:H, which is subjected to several photo-excitation and annealing cycles, shows a very slow increase of both the degraded and annealed defect densities. The difference in the spin densities between the annealed and degraded states decreases with an increasing number of degradation/annealing cycles.
Comparison Study of a-SiGe Solar Cells and Materials Deposited Using Different Hydrogen Dilution
Authors: Povolny H. , Agarwal P. , Han S. , Deng X. 
Published: April 2011

ABSTRACTA-SiGe n-i-p solar cells with i-layer deposited via plasma enhanced chemical vapor deposition (PECVD) with a germane to disilane ratio of 0.72 and hydrogen dilution R=(H2 flow)/(GeH4+Si2H6 flow) values of 1.7, 10, 30, 50, 120, 180 and 240 were deposited on stainless steel substrates. This germane to disilane ratio is what we typically use for the i-layer in the bottom cell of our standard triple-junction solar cells. Solar cell current-voltage curves (J-V) and quantum efficiency (QE) were measured for these devices. Light soaking tests were performed for these devices under 1 sun light intensity at 50° C. While device with R=30 showed the highest initial efficiency, the device with R=120 exhibit higher stabilized efficiency after 1000 hours of light soaking.Single-layer a-SiGe films (∼500 nm thick) were deposited under the same conditions as the i-layer of these devices on a variety of substrates including 7059 glass, crystalline silicon, and stainless steel for visible-IR transmission spectroscopy, FTIR, and hydrogen effusion studies. It is interesting to note 1) the H content in the film decreased with increasing R based on both the IR and H effusion measurements, and 2) while the H content changes significantly with different R, the change in Eg is relatively small. This is most likely due to a change in Ge content in the film for different R.
Light Trapping by Periodically Structured TCO in the Submicrometer Range
Authors: Eisele Christopher , Nebel Christoph E. , Stutzmann Martin 
Published: April 2011

ABSTRACTAmorphous hydrogenated silicon (a-Si:H) solar cells need efficient light trapping structures to achieve high efficiency. To this end, aluminum doped zinc oxide (ZnO:Al) as a transparent front contact was periodically structured. Solar cells with grating periods between 390 and 980 nm were realized. The structures were characterized by Atomic Force Microscopy (AFM) and optical reflection. A simple formula for the wavelength where total internal reflection starts is deduced for each diffraction order. Solar cells with a periodic grating show a significant reduction in the overall reflectance which is comparable to cells with an optimized statistical texture.
Efficient 18 Å/s Solar Cells with All Silicon Layers Deposited by Hot-Wire Chemical Vapor Deposition
Authors: Wang Qi , Iwaniczko Eugene , Xu Yueqin , Gao Wei , Nelson Brent P. , Mahan A.H. , Crandall R.S. , Branz Howard M. 
Published: April 2011

ABSTRACTEfficient hydrogenated amorphous silicon (a-Si:H) n-i-p solar cells have been fabricated with all doped and undoped a-Si:H layers deposited by hot-wire chemical vapor deposition (HWCVD). The total deposition time of all layers, except the top ITO-contact, is less than 4 minutes. On an untextured stainless steel (SS) substrate, an initial efficiency of 7.12% is reached, with a stable efficiency of 5.4% after 1000 hours 1 sun light soaking. This initial efficiency is reached by incorporating into the p/i interface about 60 Å of intrinsic a-Si:H “edge” material grown under conditions near the transition to microcrystallinity. This edge layer increases the cell's fill factor from 0.60 to 0.68 and the best open-circuit voltage is about 0.88 V. Using textured Ag/ZnOcoated SS supplied by United Solar Corporation, preliminary results of an all-HWCVD solar cell give an initial efficiency of 8.7 %.
Drastic Revolution in Catalytic Cvd using “Catalytic Plate” Instead of “Hot Wire”
Authors: Masuda Atsushi , Ishibashi Yoriko , Matsumura Hideki 
Published: April 2011

ABSTRACTThermal influence on film preparation in catalytic chemical vapor deposition (Cat-CVD), often called hot-wire CVD, is investigated since heat radiation from catalyzer and thermal transport by introduced gases are one of the dominant factors to determine the film properties. It was found that catalyzer-surface area is a key parameter determining not only the deposition rate but also the thermal influence. “Catalytic platE” instead of the conventional wire was proposed in order to suppress the heat radiation with keeping the catalyzer-surface area. Cat-CVD method employing the catalytic plate is superior to conventional “hot-wirE” CVD method.
A Multilevel Metal Interconnect Technology with Intra-Metal Air-Gap for Quarter-Micron-and-Beyond High-Performance Processes
Authors: Lin Mark , Chang Chun-Yen , Huang Tiao-Yuan , Lin Mout-Lim , Lin Horng-Chin 
Published: April 2011

AbstractA multilevel metal interconnect with air-gap has been developed to reduce RC delay time for quick turn-around-time foundry manufacturing. The air-gap method has been successfully applied to 0.25 νm foundry technology. Measurements on ring oscillators confirm that the smallest delay time is indeed achieved with the air-gap method, compared with that using either conventional high-density-plasma (HDP) oxide or low-dielectric-constant spin-on-glass (SOG). In addition, we have also developed fitting equations for the delay time, thus provide a handy method for predicting the RC delay time. The oscillator delay time is also found to be critically dependent on not only the size, but also the position of the air-gap. Best delay time reduction is obtained when the air-gap is positioned in extended both above and below the metal lines to effectively reduce the fringing capacitance.
Processing, Properties, and CMP Characteristics of a Spin-on Polymer: HSQ
Authors: Lin Wei-Jung , Yang Chang-Jong , Chen Wen-Chang 
Published: April 2011

AbstractThe structures and properties of the HSQ film during the cage/network transformation were studied by curing at 300°C for 1 hour. The experimental results show that the ratio of the network/cage structure of the cured HSQ film increases from 0.21 to 0.39 by curing. The porosity of the cured film increases from 10.0% to 12.3 %, while the refractive index decreases from 1.413 to 1.376 during curing. These results suggest that the dependence of the structure and properties of the HSQ film by curing. The CMP characteristics of HSQ were studied by using different kinds of slurries and surfactant. The CMP results of polishing HSQ suggest that the hardness and charge status of the abrasive, the interaction of the surfactant with the abrasive and film surface significantly affect the polishing results.
Low Dielectric Constant Porous Silsesquioxane Films: Effect of Thermal Treatment
Authors: Siew Y. K. , Sarkar G. , Hu X. , Xu Y. , See A. 
Published: April 2011

AbstractLow dielectric constant, nanoporous hydrogen silsesquioxane (HSQ) films were prepared using hybrid templating method by addition of a sacrificial labile polymer, polybutadiene (PB). Thermal gravimetric analyzer (TGA) was employed to monitor the decomposition behavior of HSQ-PB films. Curing of HSQ and decomposition of PB were performed by a two-stage thermal treatment to obtain a defect-free film. The porosity level and pore morphology of the resultant porous films were found to be dependent upon thermal treatment conditions applied.
Ultra Low-K Inorganic Silsesquioxane Films with Tunable Electrical and Mechanical Properties
Authors: Deis Thomas A. , Saha Chandan , Moyer Eric , Chung Kyuha , Liu Youfan , Spaulding Mike , Albaugh John , Chen Wei , Bremmer Jeff 
Published: April 2011

AbstractLow-k dielectric films have been developed using a new silsesquioxane based chemistry that allows both the electrical and mechanical properties to be tuned to specific values. By controlling the composition and film processing conditions of spin-on formulations, dielectric constants in the range 1.5 to 3.0 are obtained with modulus values that range from 1 to 30 GPa. The modulus and dielectric constant are tuned by controlling porosity, which varies from 0 to >60%, and final film composition which varies from HSiO3/2 to SiO4/2. The spin-on formulation includes hydrogen silsesquioxane resin and solvents. Adjusting the ratio of solvents to resin in the spin-on formulation controls porosity. As-spun films are treated with ammonia and moisture to oxidize the resin and form a mechanically self-supporting gel. Solvent removal and further conversion to a more “silica-like” composition occur during thermal curing at temperatures of 400 to 450°C. The final film composition was controlled through both room temperature oxidation and thermal processing. Final film properties are optimized for a balance of electrical, mechanical and thermal properties to meet the specific requirements of a wide range of applications. Processed films exhibit no stress corrosion cracking or delamination upon indentation, with indenter penetration exceeding the film thickness, and followed by exposure to water at room temperature. Films also exhibit high adhesive strength (> 60MPa) and low moisture absorption. Processing conditions, composition and properties of thin are discussed.
Deposition of Fluorinated Amorphous Carbon Thin Films with Low Dielectric Constant and Thermal Stability
Authors: Han Sang-Soo , Bae Byeong-Soo 
Published: April 2011

AbstractFluorinated amorphous carbon (a-C:F) thin films were deposited by inductively coupled plasma enhanced chemical vapor deposition (ICP-CVD) with increasing CF4:CH4 gas flow rate ratio, and then annealed with increasing annealing temperature (100, 200, 300, and 400.). We have found the reduction mechanism of the dielectric constant and the thermally stable condition for the a-C:F films. On the basis of the results, the optimal condition to satisfy both the low dielectric constant and the thermal stability is followed as; the a-C:F films have to have the compatible F content to make a compromise between the two properties; the C-Fx bonding configuration has to exist as a form of C-F2 & C-F3 instead of C-F; The films should be somewhat cross-linked structure.
Grain Orientation and Strain Measurements in Sub-Micron wide Passivated Individual Aluminum Test Structures
Authors: Tamura N. , Valek B. C. , Spolenak R. , MacDowell A. A. , Celestre R. S. , Padmore H.A. , Brown W. L. , Marieb T. , Bravman J. C. , Batterman B. W. , Patel J. R. 
Published: April 2011

AbstractAn X-ray microdiffraction dedicated beamline, combining white and monochromatic beam capabilities, has been built at the Advanced Light Source. The purpose of this beamline is to address the myriad problems in Materials Science and Physics that require submicron x-ray beams for structural characterization. Many such problems are found in the general area of thin films and nano-materials. For instance, the ability to characterize the orientation and strain state in individual grains of thin films allows us to measure structural changes at a very local level. These microstructural changes are influenced heavily by such parameters as deposition conditions and subsequent treatment. The accurate measurement of strain gradients at the micron and sub-micron level finds many applications ranging from the strain state under nano-indenters to gradients at crack tips. Undoubtedly many other applications will unfold in the future as we gain experience with the capabilities and limitations of this instrument. We have applied this technique to measure grain orientation and residual stress in single grains of pure Al interconnect lines and preliminary results on post-electromigration test experiments are presented. It is shown that measurements with this instrument can be used to resolve the complete stress tensor (6 components) in a submicron volume inside a single grain of Al under a passivation layer with an overall precision of about 20 MPa. The microstructure of passivated lines appears to be complex, with grains divided into identifiable subgrains and noticeable local variations of both tensile/compressive and shear stresses within single grains.