bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hydrogen-Nitrogen Tailors Semiconductor Optoelectronics: The Case of Dilute Nitride III-V Alloys
Authors: Janotti A. 
Published: April 2011

ABSTRACTHydrogen is an omnipresent impurity in semiconductors, often associated with other impurities and native defects, strongly affecting their electronic properties by passivating deep and shallow levels, or activating isoelectronic centers, and can be intentionally or unintentionally incorporated. On the other hand, nitrogen has profound effects on the electronic structure of conventional III-V compounds: just a few percent of N can drastically lower the band gap of GaAs making it suitable for long-wavelength optical devices; isovalent doping of GaP by N leads to a quasidirect band gap with enhanced optical functionality. The large difference in electronegativity between N and other group V elements is expected to couple with the high chemical activity of H, raising crucial questions about the behavior of H in dilute nitride alloys that theories of hydrogen in conventional semiconductors or in commom-anion nitrides are unable to answer. Here we show that N can qualitatively alter the electronic behavior of hydrogen: In GaAsN, an H atom bonds to N and can act as a donor in its own right, whereas in GaAs and GaN, H is amphoteric; Nitrogen also stabilizes the complex, that is otherwise unstable against the formation of interstitial H2 molecules, reversing the effect of N on the band gap of GaAs, allowing us to interpret several recent experiments.
Donor Behaviour of Implanted Hydrogen Ions in Silicon Wafers
Authors: Barakel Damien , Martinuzzi Santo 
Published: April 2011

ABSTRACTP type Czochralski (Cz) and float-zone (FZ) grown silicon wafers were investigated with doping levels of 5×1014 and 2×1015 cm−3, respectively. Hydrogen ions are implanted at a dose of 2×1016 cm−2, at energies in the range 20 to 250 keV and are accumulated at depth Rp in the range 0.2 to 2.4 μm. After implantation the wafers are annealed between 350 and 600°C for 30 min, under argon flow. It is found that a graduated n-p junction is formed, and after metallization a photovoltaic device is obtained, which works like a solar cell. SIMS analysis shows that, around Rp, hydrogen concentration achieves 1021 cm−3. I-V and C-V curves confirm the formation of a N-type layer in which the donor concentration is about 5×1017 cm−3. When the samples are annealed at temperatures higher than 550°C the counter-doping vanishes. The observed behaviour of hydrogen is irrespective of oxygen concentrations in the wafers as it occurs in Cz (oxygen rich) like in FZ (oxygen poor) wafers. If the wafers are ion implanted with helium at the same dose and energy no junction appears. It is concluded that the agglomeration of hydrogen in silicon after ion implantation at a dose exceeding 1016 cm−2 gives rise to the formation of shallow donors.
Charge Controlled Silicon Carbide Switching Devices
Authors: Friedrichs Peter 
Published: April 2011

AbstractCharge controlled power switching devices fabricated in 4H-Silicon Carbide are discussed in this paper. After comparing possible structures, results on prototype devices are presented. The presentation will give an overview about the developments of SiC power switches at SiCED, in addition some potential applications serving as an accelerator for the SiC power switch development will be sketched. The performance of vertical JFETs will be analyzed in detail. These can be operated as a single device as well as in combination with a low voltage silicon power MOSFET. The result of the hybrid assembly is a normally off device which behaves for the user more and more like a classical MOSFET with respect to the input as well as the output characteristic. Several improvements where performed which make the device more attractive for the customer. It will be shown which factors drive these optimization and how they can be implemented. Although the primary target for this device is the >1000V blocking voltage range, it will be discussed how the huge 600V power switch market can be made accessible for SiC power devices too. Intensively the high temperature performance of SiC JFETs and Si/SiC cascodes is discussed. Additionally, other developments like silicon power MOSFETs or high voltage switches will be mentioned.
Large area single and stacked p-i-n photodiodes as a color image sensors
Authors: Louro P. , Fernandes M. , Fantoni A. , Maçarico A. , de Carvalho C.Nunes , Lavareda G. , Vieira M. 
Published: April 2011

AbstractSingle and stacked p-i-n sensing elements for image recognition and color extraction applications are presented. The aim of this work is to optimize the performance of the a-SiC:H thin films layers in order to enhance its performance when making part of the structure of large area image and color sensors. The efforts are focused mainly on doped n- and p-type layers at high and low doping levels with and without carbon. The structural and optoelectronic properties of the single layers were determined through infrared and visible spectroscopy, temperature-dependent conductivity, and were complemented by CPM measurements. Junction properties, carrier transport, photogeneration and collection efficiency are investigated from dark and illuminated current-voltage characteristics and spectral response measurements, with and without additional background illumination and under different light bias conditions. The spectral response dependence on the applied voltage and on optical bias was also studied. Results show that the spectral sensitivity is strongly dependent on the applied voltage, namely the maximum spectral sensitivity shifts with the voltage, and at certain wavelengths the spectral response goes down to zero, which allows a different selectivity, and enables color recognition.
6H and 4H-SiC Bulk Growth by PVT and Advanced PVT (APVT)
Authors: Gupta A. , Yoganathan M. , Semenas E. , Zwieback I. , Emorhokpor E. , Martin C. , Kerr T. , Souzis A. , Anderson T. , Chen J. , Tanner C. , Barrett D. , Hopkins R. , Johnson C. 
Published: April 2011

AbstractII-VI, Inc. is a commercial supplier of high-quality SiC substrates (including 2-inch and 3-inch diameter) for RF and power applications to the US market. Semi-insulating 6H-SiC single crystals, doped with vanadium and undoped (vanadium-free), as well as ntype 4H crystals have been grown using the PVT and Advanced PVT (APVT) growth techniques. The APVT process incorporates insitu synthesis and growth of of SiC crystal from Si and C precursors.Grown 6H-SiC and 4H-SiC crystals have been extensively characterized with respect to their purity, crystal quality and electrical properties. COREMA resistivity maps demonstrate that V-compensated boules exhibited axially and radially uniform resistivity around 1011 ω.cm at room temperature. Undoped (V-free) wafers contained residual boron and nitrogen at levels below 1016 atoms/cm3, and demonstrated semi-insulating properties (resistivity between 106 and 1011 ω.cm) as a result of compensation by native point defects with deep levels in the bandgap. The undoped semi-insulating crystals grown by APVT contained boron and nitrogen at 1.9ω1015 cm−3 and 3.8.1015 cm−3, respectively.High-quality 2-inch SiC wafers exhibited micropipe densities on the order of 10 cm−2 and dislocation density on the order of 104 cm−2.
Microstructural Aspects and Mechanism of Degradation of 4H-SiC PiN Diodes under Forward Biasing
Authors: Pirouz Pirouz , Zhang Ming , Galeckas Augustinas , Linnros Jan 
Published: April 2011

AbstractDevices fabricated from the wide bandgap semiconductor SiC have many advantages over those made from conventional semiconductors. Thus, performance characteristics of some 4H-SiC devices can be two orders of magnitude better than equivalent devices made from silicon. On the other hand, new and unexpected problems have emerged with the operation of some SiC devices that need to be understood and solved before further progress can be made in this area. One of the most intriguing problems has been the degradation of bipolar PiN diodes that have major advantages over unipolar Schottky barrier diodes at high blocking voltages. The electrical degradation of the PiN diodes refers to a drop in voltage under extended forward current operation. The degradation appears to be associated with the appearance of stacking faults (SFs) in the entire base region of the diode. In this paper, we discuss some puzzling aspects of stacking fault formation in such diodes. Electroluminescence as well as TEM has been used to investigate the degradation problem and, based on experimental results, the formation of stacking faults within the device, possible sources of partial dislocations responsible for the stacking faults, and the enhanced motion of dislocations under forward biasing are considered.
Characterization of SiC epilayers using high-resolution X-ray diffraction and synchrotron topography imaging
Authors: Huang Xianrong , Dudley Michael , Okojie Robert S. 
Published: April 2011

AbstractHigh-resolution X-ray diffraction is one of the most powerful and widely used techniques for accurate characterization of the lattice parameters, mismatch, alloy composition, dopant concentrations, and thickness of epitaxial materials. In this presentation, we use a series of advanced X-ray diffraction techniques, including double-axis diffraction, triple-axis diffraction, reciprocal space mapping (RSM), and synchrotron white beam X-ray topography, to characterize highly nitrogen-doped homoepitaxial 4H-SiC epilayers. Measurements reported in this work have determined that in single crystal 4H-SiC, increasing the nitrogen doping level above 4 × 1017cm#x2212;3results in corresponding increase in lattice contraction. The increase in epilayer/mismatch mismatch with doping, and the corresponding strain energy, is attributed to the substitutional nitrogen incorporated preferentially in the host carbon sites of the 4H-SiC epilayer. Also, significant lattice tilts, generally along the [1120] offcut direction (8°), exist, which are believed to be induced by the Nagai epitaxial tilt.
Extreme Service Packaging for Silicon Carbide Electronic Devices
Authors: Guinel Maxime J. F. , Rodriguez-Marek Diego , Norton M. Grant , Davis Robert B. , Bahr David F. 
Published: April 2011

AbstractElectronic devices based on single crystal SiC represent a good choice for a variety of new high temperature, high power electronics applications. The challenge is to develop a package that is resistant to thermal degradation in harsh environments. Conditions are extreme and this all but rules out only a handful of materials and materials systems. Polycrystalline SiC is the material that we have chosen to study as a suitable package and materials suitability/compatibility has been considered on several levels.
Investigation of Mechanical Integrity and its effect on Polishing for Novel Polyurethane Polishing Pad
Authors: Zantye Parshuram , Mudhivarthi S. , Sikder A. K. , Kumar Ashok , Ostapenko S. , Harmon Julie 
Published: April 2011

AbstractThere is a widespread interest in development and characterization of CMP consumables due to an existing and potential market, as the CMP process becomes widely accepted in the field of microelectronics fabrication. A non-destructive Ultra Sound Testing (UST) technique developed at the University of South Florida has been successfully used in the past to map the variation of specific gravity over the entire volume of the pad. To gage the impact of the variation in specific gravity with in the body of the polishing pad, the results of UST of pads need to be correlated with actual polishing performance of the pad. In this research, UST was performed on IC 1000 Suba IV/ A4 polishing pad, and novel polyurethane pads, Pad A (with sub pad) and Pad B (without sub pad). The novel pads have been specifically developed for Interlayer Dielectric (ILD) polishing. 6 inch coupons from polishing pad regions of interest (high and low ultra sound transmission) determined after the ultrasound map were punched out and further evaluated. The mechanical properties of the pad material from the coupons were evaluated using Dynamic Mechanical Analysis (DMA) and tribological properties were evaluated by performing CMP on 6 inch coupons in the CETR CMP tester.
Micro Feature Pad Development and Its Performance in Chemical Mechanical Planarization
Authors: Lee Sunghoon , Dornfeld David A. 
Published: April 2011

AbstractThere are many elements affecting CMP performance such as the slurry, pad, process parameters and pad conditioning. Among these, the pad is considered to be one of the most important parts because of its deterioration during polishing. However, specific pad design techniques have not yet been fully investigated. In this paper, conventional polyurethane pad characteristics are investigated. A pad design based on this analysis is suggested. Prototype pads are fabricated using micro molding and are used in an experiment for examining the pad deterioration mechanism.
Characterization of CMP Pad Surface Texture and Pad-Wafer Contact
Authors: Muldowney Gregory P. , James David B. 
Published: April 2011

AbstractSurface texture of CMP polishing pads varies considerably with the intrinsic microstructure of the pad, the addition of perforations or grooves, and the means of surface conditioning. The state of pad-wafer contact is determined by both large and small-scale texture in the top pad asperity layer and by the interaction of the top pad and sub-pad.A flow-based texture characterization test was applied to several types of CMP polishing pads to describe the asperity layer as a porous media having a void fraction and characteristic length. Fluid pressure loss profiles were measured in a radial flow geometry across pad samples pressed against a flat instrumented plate. Symmetry of the profiles revealed the extent of contact between the pad and the plate, and curvature of the profiles showed the relative contributions of viscous and inertial flow among the asperities. Sub-pads, grooving, and conditioning all increased padwafer contact and the effective resistance of the surface texture, improving flow uniformity. Soft pads showed higher inertial flow influence than fixed abrasives with regularly spaced asperities. The results demonstrate that pad surface texture has a strong influence on heat and mass transfer at the wafer surface in CMP. Implications are discussed for both pad design and CMP modeling.
Metrology of Psiloquest's Application Specific Pads (ASP) for CMP Applications
Authors: Zantye Parshuram B. , Mudhivarthi S. , Sikder Arun K. , Kumar Ashok , Obeng Yaw 
Published: April 2011

AbstractThere is a need to develop a metrology metrics for evaluation of pad CMP performance before putting them in to service. This has been attempted on Psiloquest's application specific pads (ASP) in which the pad surface is tuned to match the mechanical properties of the target substrate. The ASP is made up of thermoplastic foams co extruded with condensed polyolefin. The chemical and mechanical properties of the pad-wafer interface are tuned by coating the pad with ceramic thin films by surface coating method such as chemical vapor deposition (CVD). The surface of the pad is characterized using metrology techniques such as ultra sound reflectivity, XPS and nanoindentation. The cross section of the pads was characterized using SEM. The mechanical properties of bulk pad materials were studied using Dynamic Mechanical Analysis (DMA). A test was performed on the pads to measure the static coefficient of friction (COF) and wear rate. The pads were polished using CETR CP-4 bench top CMP tester to evaluate the dynamic COF, Acoustic Emission (AE) signal and removal rate during a simulated Tungsten CMP process. The thickness of the ceramic coating on the surface of the ASP played an important role in determining these tribological properties. The results of the various static and dynamic tests performed on the pad were cross tabulated to evaluate their correlation.
WID Rnit Variation Improvements for HSS STI CMP Process using Modified Scribe Lane Pattern Design
Authors: Kwon Hyuk , Choi Yong-Soo , Lee Sang-Hwa , Choi Geun-Min , Song Yong-Wook , Yoon Gyu-Han 
Published: April 2011

AbstractIn the scribe lane, which is located at the frame neighboring two chips, most of the test patterns for monitoring electrical characteristics of memory device as well as various key patterns for photo process are formed. The pattern density of these regions is lower than that of the main chip area, and cause nitride erosion by dishing phenomena during HSS STI CMP process. Nitride erosion occurred in the scribe lane region, could the affect erosion properties of cell region in main chip area, results in within die remain nitride variation and marginal fail in device operation. In this work, in order to prevent these problems, pattern design in the scribe lane was modified so as not to occurs within die remain nitride variation. The effects of improvement in within die remain nitride variation were investigated by FIB-TEM analysis and its correlation with electrical properties were explained.
Rare-earth doped Si nanostructures for Microphotonics
Authors: Pacifici D. , Franzò G. , Iacona F. , Irrera A. , Boninelli S. , Miritello M. , Priolo F. 
Published: April 2011

AbstractIn the present paper, we will review our work on rare-earth doped Si nanoclusters. The samples have been obtained by implanting the rare-earth (e.g. Er) in a film containing preformed Si nanocrystals. After the implant, samples have been treated at 900°C for 1h. This annealing temperature is not enough to re-crystallize all of the amorphized Si clusters. However, even if the Si nanoclusters are in the amorphous phase, they can still efficiently transfer the energy to nearby rare-earth ions. We developed a model for the Si nanoclusters-Er system, based on an energy level scheme taking into account the coupling between each Si nanocluster and the neighboring Er ions. By fitting the data, we were able to determine a value of 3×10−15cm3s−1for the Si nanocluster-Er coupling coefficient. Moreover, a strong cooperative up-conversion mechanism between two excited Er ions and characterized by a coefficient of 7×10−17cm3s−1, is shown to be active in the system, demonstrating that more than one Er ion can be excited by the same nanocluster. We show that the overall light emission yield of the Er related luminescence can be enhanced by using higher concentrations of very small nanoaggregates. Eventually, electroluminescent devices based on rare-earth doped Si nanoclusters will be demonstrated.
The dot size effect of amorphous silicon quantum dot on 1.54-μmErluminescence
Authors: Park Nae-Man , Kim Tae-Youb , Sung Gun Yong , Kim Baek-Hyun , Park Seong-Ju , Cho Kwan Sik , Shin Jung H. , Lee Jung-Kun , Nastasi Michael 
Published: April 2011

AbstractThe role of the size of amorphous silicon quantum dots in the Er luminescence at 1.54 μm was investigated. As the dot size was increased, the more Er ions were located near one dot due to its large surface area and more Er ions interacted with other ones. This Er-Er interaction caused a weak photoluminescence intensity despite the increase in the effective excitation cross section. The critical dot size, needed to take advantage of the positive effect on Er luminescence, is considered to be about 2.0 nm, below which a small dot is very effective in the efficient luminescence of Er.
Omnidirectional reflectance and optical gap properties of Si/SiO2Thue-Morse quasicrystals
Authors: Negro L. Dal , Stolfi M. , Yi Y. , Michel J. , Duan X. , Kimerling L.C. , Leblanc J. , Haavisto J. 
Published: April 2011

AbstractAperiodic one dimensional Si/SiO2Thue-Morse (T-M) multilayer structures have been fabricated, for the first time, in order to investigate both the band-gap behavior, with respect to the system size (band-gap scaling), and the omnidirectional reflectance of the fundamental optical band-gap. Variable angle reflectance data have experimentally demonstrated a large reflectance band-gap in the optical spectrum of a T-M quasicrystal, in agreement with transfer matrix simulations. We have explained the physical origin of the T-M omnidirectional band-gap as a result of periodic spatial correlations in the self-similar T-M structure, as revealed by Fourier Transform and Wavelet analysis. The unprecedented degree of structural flexibility showed by T-M systems can provide an attractive alternative to photonic crystals for the fabrication of photonic devices.
Preparation of opal-based PBG crystals to develop multiple stop bands
Authors: Chen Yen-Tai , Liau Leo Chau-Kuang 
Published: April 2011

AbstractOpal-based photonic band gap (PBG) crystals with multiple stop bands were prepared utilizing a sol-gel method. The fabricating procedure includes colloidal crystal syntheses, dispersion, sedimentation, coating, and thermal treatments. Each of the steps can affect the PBG properties, such as stop band locations and ranges. Different stop bands of the photonic crystals can be produced by controlling the particle sizes prepared by the colloidal crystal syntheses. A PBG crystal film with a certain stop band was formed using a particular size of the colloidal crystals coated on glass substrates. In this study, two layers of different particle sizes of PBG crystal were fabricated by different deposition conditions to demonstrate the feasibility of producing multiple stop bands. These conditions can affect the stack layers and structural regularity for forming the PBG layers. In addition, the stop band intensity of the PBG layer can be further improved by the step of thermal treatments. Results imply that multiple stop bands can be feasibly designed and produced as multiple PBG layers coating with a certain SiO2particle size for each layer.
Hybrid Integrated Microphotonics and It's Applications
Authors: Jung Suntae , Kim Taeil 
Published: April 2011

AbstractHybrid Integration of passive and opto-electronic devices is emerging as a key technology of optical component, because it can increase functionality and reliability of optical device module, lowers the packaging cost and enables automated manufacturing. Main applications of hybrid integrated microphotonic devices are FTTH system and metro access network.There are various technical issues in hybrid integration modules. It requires connecting an active device to a passive waveguide. The embedded functional devices such as grating, coupler, switch and filter are essential elements to improve optical performance of integrated devices. The package solution for low cost and small size is also required.We have developed SSC LD(Spot Size Converted Laser Diode) and RMF PD(Reflection Mirror Facet Photo Diode) for connecting to planar waveguide. Simple and cost-effective silica PLC platform with terraced-silica, PLC grating and coupler have been developed. Using these technologies, we have made bi-directional diplexer, triplexer and ECL(External Cavity Laser).
Optoelectronic Simulation of the Klein Paradox based on Negative Refraction Phenomenon
Authors: Güney Durdu Ö. , Meyer David A. 
Published: April 2011

AbstractHaving shown elsewhere [1] that the Klein paradox for the Klein-Gordon (KG) equation of spin-zero particle manifests exactly the same kind of wave propagation and negative refraction phenomena, which also exist in the scattering of TM (transverse-magnetic) –polarized electromagnetic (EM) wave incident on a left handed medium (LHM), we show in this paper that it is possible to simulate the Klein paradox, using this peculiar feature of LHMs. Real time control and processing of certain quantum systems, involving controlled pair production rate and distribution, among others, could be achieved by this optoelectronic simulator using appropriate transformations and approximations.