Showing papers on "Silicon published in 2004"
TL;DR: In this article, the structural changes in silicon electrochemically lithiated and delithiated at room temperature were studied by X-ray powder diffraction, and it was shown that highly lithiated amorphous silicon suddenly crystallizes at 50 mV to form a new lithium-silicon phase, identified as This phase is the fully lithiated phase for silicon at room-temperature, not as is widely believed.
Abstract: The structural changes in silicon electrochemically lithiated and delithiated at room temperature were studied by X-ray powder diffraction. Crystalline silicon becomes amorphous during lithium insertion, confirming previous studies. Highly lithiated amorphous silicon suddenly crystallizes at 50 mV to form a new lithium-silicon phase, identified as This phase is the fully lithiated phase for silicon at room temperature, not as is widely believed. Delithiation of the phase results in the formation of amorphous silicon. Cycling silicon anodes above 50 mV avoids the formation of crystallized phases completely and results in better cycling performance. © 2004 The Electrochemical Society. All rights reserved.
1,686 citations
TL;DR: An approach based on a metal–oxide–semiconductor (MOS) capacitor structure embedded in a silicon waveguide that can produce high-speed optical phase modulation is described and an all-silicon optical modulator with a modulation bandwidth exceeding 1 GHz is demonstrated.
Abstract: Silicon has long been the optimal material for electronics, but it is only relatively recently that it has been considered as a material option for photonics1. One of the key limitations for using silicon as a photonic material has been the relatively low speed of silicon optical modulators compared to those fabricated from III–V semiconductor compounds2,3,4,5,6 and/or electro-optic materials such as lithium niobate7,8,9. To date, the fastest silicon-waveguide-based optical modulator that has been demonstrated experimentally has a modulation frequency of only ∼20 MHz (refs 10, 11), although it has been predicted theoretically that a ∼1-GHz modulation frequency might be achievable in some device structures12,13. Here we describe an approach based on a metal–oxide–semiconductor (MOS) capacitor structure embedded in a silicon waveguide that can produce high-speed optical phase modulation: we demonstrate an all-silicon optical modulator with a modulation bandwidth exceeding 1 GHz. As this technology is compatible with conventional complementary MOS (CMOS) processing, monolithic integration of the silicon modulator with advanced electronics on a single silicon substrate becomes possible.
1,612 citations
TL;DR: The experimental demonstration of fast all-optical switching on silicon using highly light-confining structures to enhance the sensitivity of light to small changes in refractive index and confirm the recent theoretical prediction of efficient optical switching in silicon using resonant structures.
Abstract: Photonic circuits, in which beams of light redirect the flow of other beams of light, are a long-standing goal for developing highly integrated optical communication components1,2,3. Furthermore, it is highly desirable to use silicon—the dominant material in the microelectronic industry—as the platform for such circuits. Photonic structures that bend, split, couple and filter light have recently been demonstrated in silicon4,5, but the flow of light in these structures is predetermined and cannot be readily modulated during operation. All-optical switches and modulators have been demonstrated with III–V compound semiconductors6,7, but achieving the same in silicon is challenging owing to its relatively weak nonlinear optical properties. Indeed, all-optical switching in silicon has only been achieved by using extremely high powers8,9,10,11,12,13,14,15 in large or non-planar structures, where the modulated light is propagating out-of-plane. Such high powers, large dimensions and non-planar geometries are inappropriate for effective on-chip integration. Here we present the experimental demonstration of fast all-optical switching on silicon using highly light-confining structures to enhance the sensitivity of light to small changes in refractive index. The transmission of the structure can be modulated by up to 94% in less than 500 ps using light pulses with energies as low as 25 pJ. These results confirm the recent theoretical prediction16 of efficient optical switching in silicon using resonant structures.
1,506 citations
TL;DR: The fabrication of nickel silicide/silicon (NiSi/Si) nanowire heterostructures with atomically sharp metal–semiconductor interfaces is demonstrated and field-effect transistors based on those heterostructure in which the source–drain contacts are defined by the metallic NiSi nanowires regions are produced.
Abstract: Substantial effort has been placed on developing semiconducting carbon nanotubes and nanowires as building blocks for electronic devices--such as field-effect transistors--that could replace conventional silicon transistors in hybrid electronics or lead to stand-alone nanosystems. Attaching electric contacts to individual devices is a first step towards integration, and this step has been addressed using lithographically defined metal electrodes. Yet, these metal contacts define a size scale that is much larger than the nanometre-scale building blocks, thus limiting many potential advantages. Here we report an integrated contact and interconnection solution that overcomes this size constraint through selective transformation of silicon nanowires into metallic nickel silicide (NiSi) nanowires. Electrical measurements show that the single crystal nickel silicide nanowires have ideal resistivities of about 10 microOmega cm and remarkably high failure-current densities, >10(8) A cm(-2). In addition, we demonstrate the fabrication of nickel silicide/silicon (NiSi/Si) nanowire heterostructures with atomically sharp metal-semiconductor interfaces. We produce field-effect transistors based on those heterostructures in which the source-drain contacts are defined by the metallic NiSi nanowire regions. Our approach is fully compatible with conventional planar silicon electronics and extendable to the 10-nm scale using a crossed-nanowire architecture.
1,019 citations
TL;DR: In this article, the effect of aluminum-doped zinc oxide (ZnO:Al) front contact and the role of the back reflector on the performance of thin-film silicon solar cells is investigated.
1,013 citations
IBM1
TL;DR: The fabrication and accurate measurement of propagation and bending losses in single-mode silicon waveguides with submicron dimensions fabricated on silicon-on-insulator wafers with record low numbers can be used as a benchmark for further development of silicon microphotonic components and circuits.
Abstract: We report the fabrication and accurate measurement of propagation and bending losses in single-mode silicon waveguides with submicron dimensions fabricated on silicon-on-insulator wafers. Owing to the small sidewall surface roughness achieved by processing on a standard 200mm CMOS fabrication line, minimal propagation losses of 3.6+/-0.1dB/cm for the TE polarization were measured at the telecommunications wavelength of 1.5microm. Losses per 90 masculine bend are measured to be 0.086+/-0.005dB for a bending radius of 1microm and as low as 0.013+/-0.005dB for a bend radius of 2microm. These record low numbers can be used as a benchmark for further development of silicon microphotonic components and circuits.
999 citations
TL;DR: In this article, an in situ X-ray diffraction study of the reaction of lithium with a-Si has been performed, and the results confirm that a new crystalline Li 15 Si 4 phase is formed below 30 mV as Li/Li + as first reported by Obrovac and Christensen in an article published in Electrochemical and Solid-State Letters.
Abstract: Silicon is a very promising candidate to replace graphite as the anode in Li-ion batteries because of its very high theoretical capacity. It has not yet made its way into commercial cells because of severe problems with the charge and discharge cycling of the material. It seems that amorphous silicon and amorphous silicon-containing alloys exhibit much improved cycling performance. Therefore, it is desirable to fully understand the reaction of Li with a-Si. To this end, an in situ X-ray diffraction study of the reaction of lithium with a-Si has been performed. The results confirm that a new crystalline Li 15 Si 4 phase is formed below 30 mV as Li/Li + as first reported by Obrovac and Christensen in an article published in Electrochemical and Solid-State Letters. However, the crystalline phase only forms for films of a-Si above a critical thickness of about 2 μm.
991 citations
TL;DR: In this article, single-crystal silicon nanowires with diameters approaching molecular dimensions were synthesized using gold nanocluster-catalyzed 1D growth using high-resolution transmission electron microscopy studies.
Abstract: Single-crystal silicon nanowires with diameters approaching molecular dimensions were synthesized using gold nanocluster-catalyzed 1D growth. High-resolution transmission electron microscopy studies show that silicon nanowires grown with silane reactant in hydrogen are single crystal with little or no visible amorphous oxide down to diameters as small as 3 nm. Structural characterization of a large number of samples shows that the smallest-diameter nanowires grow primarily along the 〈110〉 direction, whereas larger nanowires grow along the 〈111〉 direction. In addition, cross-sectional transmission electron microscopy was used to address the importance of surface energetics in determining the growth direction of the smallest nanowires. The ability to prepare well-defined molecular-scale single-crystal silicon nanowires opens up new opportunities for both fundamental studies and nanodevice applications.
952 citations
TL;DR: In this paper, a leading-edge 90-nm technology with 1.2-nm physical gate oxide, 45-nm gate length, strained silicon, NiSi, seven layers of Cu interconnects, and low/spl kappa/CDO for high-performance dense logic is presented.
Abstract: A leading-edge 90-nm technology with 1.2-nm physical gate oxide, 45-nm gate length, strained silicon, NiSi, seven layers of Cu interconnects, and low-/spl kappa/ CDO for high-performance dense logic is presented. Strained silicon is used to increase saturated n-type and p-type metal-oxide-semiconductor field-effect transistors (MOSFETs) drive currents by 10% and 25%, respectively. Using selective epitaxial Si/sub 1-x/Ge/sub x/ in the source and drain regions, longitudinal uniaxial compressive stress is introduced into the p-type MOSEFT to increase hole mobility by >50%. A tensile silicon nitride-capping layer is used to introduce tensile strain into the n-type MOSFET and enhance electron mobility by 20%. Unlike all past strained-Si work, the hole mobility enhancement in this paper is present at large vertical electric fields in nanoscale transistors making this strain technique useful for advanced logic technologies. Furthermore, using piezoresistance coefficients it is shown that significantly less strain (/spl sim/5 /spl times/) is needed for a given PMOS mobility enhancement when applied via longitudinal uniaxial compression versus in-plane biaxial tension using the conventional Si/sub 1-x/Ge/sub x/ substrate approach.
728 citations
TL;DR: In this article, the authors describe the use of hydrogenated amorphous silicon (a-Si:H) and hydrogenated micro-crystalline silicon (μc-Si-H) thin films (layers), both deposited at low temperatures (200°C) by plasma-assisted chemical vapour deposition (PECVD), from a mixture of silane and hydrogen.
Abstract: This paper describes the use, within p–i–n- and n–i–p-type solar cells, of hydrogenated amorphous silicon (a-Si:H) and hydrogenated microcrystalline silicon (μc-Si:H) thin films (layers), both deposited at low temperatures (200°C) by plasma-assisted chemical vapour deposition (PECVD), from a mixture of silane and hydrogen. Optical and electrical properties of the i-layers are described. These properties are linked to the microstructure and hence to the i-layer deposition rate, that in turn, affects throughput in production. The importance of contact and reflection layers in achieving low electrical and optical losses is explained, particularly for the superstrate case. Especially the required properties for the transparent conductive oxide (TCO) need to be well balanced in order to provide, at the same time, for high electrical conductivity (preferably by high electron mobility), low optical absorption and surface texture (for low optical losses and pronounced light trapping). Single-junction amorphous and microcrystalline p–i–n-type solar cells, as fabricated so far, are compared in their key parameters (Jsc, FF, Voc) with the [theoretical] limiting values. Tandem and multijunction cells are introduced; the μc-Si: H/a-Si: H or [micromorph] tandem solar cell concept is explained in detail, and recent results obtained here are listed and commented. Factors governing the mass-production of thin-film silicon modules are determined both by inherent technical reasons, described in detail, and by economic considerations. The cumulative effect of these factors results in distinct efficiency reductions from values of record laboratory cells to statistical averages of production modules. Finally, applications of thin-film silicon PV modules, especially in building-integrated PV (BIPV) are shown. In this context, the energy yields of thin-film silicon modules emerge as a valuable gauge for module performance, and compare very favourably with those of other PV technologies. Copyright © 2004 John Wiley & Sons, Ltd.
718 citations
TL;DR: Air-clad subwavelength-diameter wires have interesting properties such as tight-confinement ability, enhanced evanescent fields and large waveguide dispersions that are very promising for developing future microphotonic devices with subwa wavelength-width structures.
Abstract: Single-mode optical wave guiding properties of silica and silicon subwavelength-diameter wires are studied with exact solutions of Maxwell's equations. Single mode conditions, modal fields, power distribution, group velocities and waveguide dispersions are studied. It shows that air-clad subwavelength-diameter wires have interesting properties such as tight-confinement ability, enhanced evanescent fields and large waveguide dispersions that are very promising for developing future microphotonic devices with subwavelength-width structures.
TL;DR: In this paper, the authors present results of ideal epitaxial nucleation and growth of III−V semiconductor nanowires on silicon substrates, and demonstrate the efficient room-temperature generation of light on silicon is demonstrated by the incorporation of double heterostructure segments in such nano-structures.
Abstract: We present results of ideal epitaxial nucleation and growth of III−V semiconductor nanowires on silicon substrates. This addresses the long-time challenge of integrating high performance III−V semiconductors with mainstream Si technology. Efficient room-temperature generation of light on silicon is demonstrated by the incorporation of double heterostructure segments in such nanowires. We expect that advanced heterostructure devices, such as resonant tunneling diodes, superlattice device structures, and heterostructure photonic devices for on-chip communication, could now become available as complementary device technologies for integration with silicon.
Book•
05 Mar 2004
TL;DR: In this article, the basics of Guided Waves are discussed and a selection of photonic devices are presented. But the authors focus on the polarisation-dependent losses of waveguide devices and do not consider the effect of light-emitting devices.
Abstract: About the Authors.Foreword.Acknowledgements.1. Fundamentals.2. The Basics of Guided Waves.3. Characteristics of Optical Fibres for Communications.4. Silicon-on-Insulator (SOI) Photonics.5. Fabrication of Silicon Waveguide Devices.6. A Selection of Photonic Devices.7. Polarisation-dependent Losses: Issues for Consideration.8. Prospects for Silicon Light-emitting Devices.Index.
TL;DR: In this article, the structural, electronic, and optical properties of hydrogen-passivated silicon nanowires along [110] and [111] directions with diameter d up to 4.2 nm from first principles were investigated.
Abstract: We investigate the structural, electronic, and optical properties of hydrogen-passivated silicon nanowires along [110] and [111] directions with diameter d up to 4.2 nm from first principles. The size and orientation dependence of the band gap is investigated and the local-density gap is corrected with the GW approximation. Quantum confinement becomes significant for d<2.2 nm, where the dielectric function exhibits strong anisotropy and new low-energy absorption peaks start to appear in the imaginary part of the dielectric function for polarization along the wire axis.
Patent•
28 May 2004TL;DR: In this article, the functionalized silicon compounds are attached to the surface of a substrate comprising silica, such as a glass substrate, to provide a functionalized surface on the substrate to which molecules, including polypeptides and nucleic acids, may be attached.
Abstract: Provided are functionalized silicon compounds and methods for their synthesis and use. The functionalized silicon compounds include at least one activated silicon group and at least one derivatizable functional group. Exemplary derivatizable functional groups include hydroxyl, amino, carboxyl and thiol, as well as modified forms thereof, such as activated or protected forms. The functionalized silicon compounds may be covalently attached to surfaces to form functionalized surfaces which may be used in a wide range of different applications. In one embodiment, the silicon compounds are attached to the surface of a substrate comprising silica, such as a glass substrate, to provide a functionalized surface on the substrate, to which molecules, including polypeptides and nucleic acids, may be attached. In one embodiment, after covalent attachment of a functionalized silicon compound to the surface of a solid silica substrate to form a functionalized coating on the substrate, an array of nucleic acids may be covalently attached to the substrate. Thus, the method permits the formation of high density arrays of nucleic acids immobilized on a substrate, which may be used, for example, in conducting high volume nucleic acid hybridization assays.
TL;DR: The microstructured silicon (μs-Si) as mentioned in this paper is a type of material that can be deposited and patterned onto plastic substrates to yield mechanically flexible thin film transistors that have excellent electrical properties.
Abstract: Free-standing micro- and nanoscale objects of single crystal silicon can be fabricated from silicon-on-insulator wafers by lithographic patterning of resist, etching of the exposed top silicon, and removing the underlying SiO2 to lift-off the remaining silicon. A large collection of such objects constitutes a type of material that can be deposited and patterned, by dry transfer printing or solution casting, onto plastic substrates to yield mechanically flexible thin film transistors that have excellent electrical properties. Effective mobilities of devices built with this material, which we refer to as microstructured silicon (μs-Si), are demonstrated to be as high as 180cm2∕Vs on plastic substrates. This form of “top down” microtechnology might represent an attractive route to high performance flexible electronic systems.
TL;DR: In this article, the authors analyzed the nonlinear effects of single-crystal silicon micro-resonators with the focus on mechanical nonlinearities and showed that the higher energy density attainable with the silicon resonators can partially compensate for the small microresonator size.
Abstract: Nonlinear effects in single-crystal silicon microresonators are analyzed with the focus on mechanical nonlinearities. The bulk acoustic wave (BAW) resonators are shown to have orders-of-magnitude higher energy storage capability than flexural beam resonators. The bifurcation point for the silicon BAW resonators is measured and the maximum vibration amplitude is shown to approach the intrinsic material limit. The importance of nonlinearities in setting the limit for vibration energy storage is demonstrated in oscillator applications. The phase noise calculated for silicon microresonator-based oscillators is compared to the conventional macroscopic quartz-based oscillators, and it is shown that the higher energy density attainable with the silicon resonators can partially compensate for the small microresonator size. Scaling law for microresonator phase noise is developed.
TL;DR: In this article, the optical properties, chemical composition, and crystallinity of silicon microstructures formed in the presence of SF6 by femtosecond laser irradiation and by nanosecond LIDAR irradiation were compared.
Abstract: We compare the optical properties, chemical composition, and crystallinity of silicon microstructures formed in the presence of SF6 by femtosecond laser irradiation and by nanosecond laser irradiation. In spite of very different morphology and crystallinity, the optical properties and chemical composition of the two types of microstructures are very similar. The structures formed with femtosecond (fs) pulses are covered with a disordered nanocrystalline surface layer less than 1 μm thick, while those formed with nanosecond (ns) pulses have very little disorder. Both ns-laser-formed and fs-laser-formed structures absorb near-infrared (1.1–2.5 μm) radiation strongly and have roughly 0.5% sulfur impurities.
TL;DR: In this article, the PECVD growth process, and the microfabrication techniques needed to produce well defined carbon nanotube based micro-electron sources for use in novel parallel e-beam lithography and high frequency microwave amplifier systems are reviewed.
Abstract: Micro and nano-structurally rich carbon materials are alternatives to conventional metal/silicon tips for field emission sources. In particular, carbon nanotubes exhibit extraordinary field emission properties because of their high electrical conductivity, their high aspect ratio “whisker-like” shape for optimum geometrical field enhancement, and remarkable thermal stability. This paper will review the PECVD growth process, and the microfabrication techniques needed to produce well defined carbon nanotube based micro-electron sources for use in novel parallel e-beam lithography and high frequency microwave amplifier systems.
TL;DR: In this paper, a water-soluble acrylic acid (AAc) was covalently grafted to silicon nanoparticles to increase their dispersibility and improve their photoluminescence stability against degradation by water.
Abstract: UV-induced graft polymerization of acrylic acid (AAc) on the surface of silicon nanoparticles was used to prepare a stable aqueous luminescent silicon nanoparticle solution. By grafting a water-soluble polymer on the particle surface, the dispersions in water of the silicon nanoparticles became very stable and clear aqueous solutions could be obtained. XPS and NMR spectroscopy confirmed that PAAc was covalently grafted to the silicon nanoparticles. The grafted PAAc on silicon particles increased not only the dispersibility but also improved the photoluminescence stability of the silicon nanoparticles against degradation by water. The surface-modified nanoparticles were used as biological labels for cell imaging. The Si quantum dot labels exihibited bright fluorescence images and provided higher resistance to photobleaching than the commonly used organic dyes.
TL;DR: In this article, room temperature negative differential resistance (NDR) has been measured through individual organic molecules on degenerately doped Si(100) surfaces using ultrahigh vacuum scanning tunneling microscopy (STM).
Abstract: Room temperature negative differential resistance (NDR) has been measured through individual organic molecules on degenerately doped Si(100) surfaces using ultrahigh vacuum scanning tunneling microscopy (STM). For styrene molecules on n-type Si(100), NDR is observed only for negative sample bias because positive sample bias leads to electron stimulated desorption. By replacing styrene with a saturated organic molecule (2,2,6,6-tetramethyl-1-piperidinyloxy), electron stimulated desorption is not observed at either bias polarity. In this case, NDR is observed only for negative sample bias on n-type Si(100) and for positive sample bias on p-type Si(100). This unique behavior is consistent with a resonant tunneling mechanism via molecular orbitals and opens new possibilities for silicon-based molecular electronic devices and chemical identification with STM at the single-molecule level.
TL;DR: In this paper, the fabrication of chip-sized alkali atom vapor cells using silicon micromachining and anodic bonding technology is described, which may find use in highly miniaturized atomic frequency references or magnetometers.
Abstract: We describe the fabrication of chip-sized alkali atom vapor cells using silicon micromachining and anodic bonding technology. Such cells may find use in highly miniaturized atomic frequency references or magnetometers. The cells consist of cavities etched in silicon, with internal volumes as small as 1 mm3. Two techniques for introducing cesium and a buffer gas into the cells are described: one based on chemical reaction between cesium chloride and barium azide, and the other based on direct injection of elemental cesium within a controlled anaerobic environment. Cesium optical absorption and coherent population trapping resonances were measured in the cells.
Patent•
02 Dec 2004TL;DR: In this paper, a method for depositing nano-porous low dielectric constant films by reacting an oxidizable silicon containing compound or mixture comprising an oxidisable silicon component and a non-silicon component having thermally liable groups with nitrous oxide, oxygen, ozone, or other source of reactive oxygen in gas-phase plasmaenhanced reaction is presented.
Abstract: The present invention provides a method for depositing nano-porous low dielectric constant films by reacting an oxidizable silicon containing compound or mixture comprising an oxidizable silicon component and an oxidizable non-silicon component having thermally liable groups with nitrous oxide, oxygen, ozone, or other source of reactive oxygen in gas-phase plasma-enhanced reaction. The deposited silicon oxide based film is annealed to form dispersed microscopic voids that remain in a nano-porous silicon oxide based film having a low-density structure. The nano-porous silicon oxide based films are useful for forming layers between metal lines with or without liner or cap layers. The nano-porous silicon oxide based films may also be used as an intermetal dielectric layer for fabricating dual damascene structures. Preferred nano-porous silicon oxide based films are produced by reaction of methylsilyl-1,4-dioxinyl ether or methylsiloxanyl furan and 2,4,6-trisilaoxane or cyclo-1,3,5,7-tetrasilylene-2,6-dioxy-4,8 dimethylene with nitrous oxide or oxygen followed by a cure/anneal that includes a gradual increase in temperature.
TL;DR: In this article, the phonon Boltzmann equation model is used to study the thermal conductivity of nanocomposites with nanowires embedded in a host semiconductor material.
Abstract: In this paper, the phonon Boltzmann equation model is established to study the phonon thermal conductivity of nanocomposites with nanowires embedded in a host semiconductor material. Special attention has been paid to cell--cell interaction using periodic boundary conditions. The simulation shows that the temperature profiles in nanocomposites are very different from those in conventional composites due to ballistic phonon transport at nanoscale. Such temperature profiles cannot be captured by existing models in literature. The general approach is applied to study silicon wire/germanium matrix nanocomposites. We predict the thermal conductivity dependence on the size of the nanowires and the volumetric fraction of the constituent materials. At constant volumetric fraction the smaller the wire diameter, the smaller is the thermal conductivity of periodic two-dimensional nanocomposites. For fixed silicon wire dimension, the lower the atomic percentage of germanium, the lower the thermal conductivity of the nanocomposites. Comparison is also made with the thermal conductivity of superlattices. The results of this study can be used to direct the development of high efficiency thermoelectric materials.
Book•
02 Jun 2004
TL;DR: The Electron System Phenomenological and Atomistic Approaches to Diffusion Thermodynamics Reaction Kinetics Exchange of Matter Between Phases Bibliography Intrinsic Point Defects Concentration in Thermal Equilibrium Diffusion of Intrininsic Points Defect, Self-Diffusion and Tracer Diffusion Vacancies Self-Interstitials Frenkel Pairs Bulk Recombination and Bulk Processes Surface Recombinations and Surface Processes Initial Conditions Bibliography Impurity Diffusion in Silicon Basic Mechanisms Impurity-Point-Defect Pairs Diffusion via Mobile
Abstract: Preface / Frequently Used Symbols / Explanation of Frequently Used Abbreviations Fundamental Concepts Silicon and Its Imperfections The Electron System Phenomenological and Atomistic Approaches to Diffusion Thermodynamics Reaction Kinetics Exchange of Matter Between Phases Bibliography Intrinsic Point Defects Concentration in Thermal Equilibrium Diffusion of Intrinsic Point Defects Self-Diffusion and Tracer Diffusion Vacancies Self-Interstitials Frenkel Pairs Bulk Recombination and Bulk Processes Surface Recombination and Surface Processes Initial Conditions Bibliography Impurity Diffusion in Silicon Basic Mechanisms Impurity-Point-Defect Pairs Diffusion of Substitutional Impurities via Mobile Complexes with Intrinsic Point Defects Pair-Diffusion Models Frank-Turnbull Mechanism Kick-Out Mechanism Bibliography Isovalent Impurities Carbon Germanium Tin Bibliography Dopants Dopant Clusters Ion Pairing Boron Aluminum Gallium Indium Nitrogen Phosphorus Arsenic Antimony Bibliography Chalcogens Oxygen Sulfur Selenium Tellurium Bibliography Halogens Fluorine Chlorine Bromine Bibliography List of Tables / List of Figures / Index
TL;DR: In this paper, the in situ generation of the Au clusters as well as the growth parameters of the whiskers are discussed, and the experimentally observed radius dependence of the growth velocity of the nanowiskers is opposite to what is known for VLS growth based on chemical vapor deposition.
Abstract: Silicon nanowhiskers in the diameter range of 70 to 200 nm were grown on 〈111〉-oriented silicon substrates by molecular-beam epitaxy. Assuming the so-called “vapor–liquid–solid” (VLS) growth process to operate, we initiated the growth by using small clusters of gold at the silicon interface as seeds. The in situ generation of the Au clusters as well as the growth parameters of the whiskers are discussed. The experimentally observed radius dependence of the growth velocity of the nanowhiskers is opposite to what is known for VLS growth based on chemical vapor deposition and can be explained by an ad-atom diffusion on the surface of the whiskers.
TL;DR: In this article, the photoresponse to sub-THz (120GHz) radiation of Si field effect transistors (FETs) with nanometer and sub-micron gate lengths at 300K was investigated.
Abstract: We report on experiments on photoresponse to sub-THz (120GHz) radiation of Si field-effect transistors (FETs) with nanometer and submicron gate lengths at 300K. The observed photoresponse is in agreement with predictions of the Dyakonov–Shur plasma wave detection theory. This is experimental evidence of the plasma wave detection by silicon FETs. The plasma wave parameters deduced from the experiments allow us to predict the nonresonant and resonant detection in THz range by nanometer size silicon devices—operating at room temperature.
TL;DR: Photoluminescence measurements showed that surface treatment significantly stabilized the PL properties of the nanoparticles against degradation and allowed some narrowing and tuning of the PL spectrum.
Abstract: CO2 laser induced pyrolysis of silane was used to produce silicon nanoparticles with an average diameter as small as 5 nm at high rates (up to 200 mg/h). Etching these particles with a mixture of hydrofluoric acid (HF) and nitric acid (HNO3) reduces their size and passivates their surface such that they exhibit bright visible photoluminescence (PL). This paper describes the attachment of organic molecules to hydrogen-terminated and hydroxyl-terminated surfaces of these nanoparticles. Stable particle dispersions in various solvents were obtained by treatment of hydrogen-terminated surfaces with octadecene or undecylenic acid and by treatment of hydroxyl-terminated surfaces with octadecyltrimethoxysilane. Transmission electron microscopy showed that the surface-functionalized particles were well dispersed and crystalline. FTIR spectroscopy confirmed the expected reactions of the organic molecules with the particle surfaces. Photoluminescence measurements showed that surface treatment significantly stabilize...
TL;DR: Single-crystal field effect transistors of the organic semiconductor dithiophene-tetrathiafulvalene (DT-TTF) were prepared by drop casting and the highest hole mobility observed was 1.4 cm2/Vs, which is the highest reported for an Organic semiconductor not based on pentacene.
Abstract: Single-crystal field effect transistors of the organic semiconductor dithiophene-tetrathiafulvalene (DT-TTF) were prepared by drop casting. Long, thin crystals connected two microfabricated gold electrodes, and a silicon substrate was used as a back gate. The highest hole mobility observed was 1.4 cm2/Vs, which is the highest reported for an organic semiconductor not based on pentacene. A high ON/OFF ratio of at least 7 x 105 was obtained for this device.
TL;DR: In this paper, a conceptual analysis of the various aspects in the morphology and formation mechanisms of porous silicon in light of currently available information on the fundamental reaction processes on silicon electrodes is presented.
Abstract: Porous silicon exhibits extremely rich morphological features resulting from a set of very complex reaction processes at the silicon/electrolyte interface. Numerous theories have been proposed since its discovery more than four decades ago, but there is still a lack of complete understanding of the formation mechanisms with respect to the observed morphological details. This paper attempts to provide a conceptual analysis of the various aspects in the morphology and formation mechanisms of porous silicon in light of currently available information on the fundamental reaction processes on silicon electrodes.