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: SiC-based ceramic matrix composites, consisting of carbon or SiC fibers embedded in a SiC-matrix, are tough ceramics when the fiber/matrix bonding is properly optimized through the use of a thin interphase.
1,358 citations
TL;DR: It is demonstrated that, different from the current consensus, Ge2Sb2Te5, the material of choice in DVD-RAM, does not possess the rocksalt structure but more likely consists of well-defined rigid building blocks that are randomly oriented in space consistent with cubic symmetry.
Abstract: Present-day multimedia strongly rely on rewritable phase-change optical memories. We demonstrate that, different from the current consensus, Ge(2)Sb(2)Te(5), the material of choice in DVD-RAM, does not possess the rocksalt structure but more likely consists of well-defined rigid building blocks that are randomly oriented in space consistent with cubic symmetry. Laser-induced amorphization results in drastic shortening of covalent bonds and a decrease in the mean-square relative displacement, demonstrating a substantial increase in the degree of short-range ordering, in sharp contrast to the amorphization of typical covalently bonded solids. This novel order-disorder transition is due to an umbrella-flip of Ge atoms from an octahedral position into a tetrahedral position without rupture of strong covalent bonds. It is this unique two-state nature of the transformation that ensures fast DVD performance and repeatable switching over ten million cycles.
1,140 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, the authors describe the evolution and properties of a new class of MOSFETs, called triple-plus (3 + )-gate devices, which offer a practical solution to the problem of the ultimate, yet manufacturable, silicon MOS-FET.
Abstract: In an ever increasing need for higher current drive and better short-channel characteristics, silicon-on-insulator MOS transistors are evolving from classical, planar, single-gate devices into three-dimensional devices with multiple gates (double-, triple- or quadruple-gate devices). The evolution and the properties of such devices are described and the emergence of a new class of MOSFETs, called triple-plus (3 + )-gate devices offer a practical solution to the problem of the ultimate, yet manufacturable, silicon MOSFET.
TL;DR: Highly sensitive and sequence-specific DNA sensors were fabricated based on silicon nanowires with single stranded probe DNA molecules covalently immobilized on the nanowire surfaces, recognizing label-free complementary ss-DNA in sample solutions when the target DNA was hybridized with the probe DNA attached on the SiNW surfaces.
Abstract: Highly sensitive and sequence-specific DNA sensors were fabricated based on silicon nanowires (SiNWs) with single stranded (ss) probe DNA molecules covalently immobilized on the nanowire surfaces. Label-free complementary (target) ss-DNA in sample solutions were recognized when the target DNA was hybridized with the probe DNA attached on the SiNW surfaces, producing a change of the conductance of the SiNWs. For a 12-mer oligonucletide probe, 25 pM of target DNA in solution was detected easily (signal/noise ratio > 6), whereas 12-mers with one base mismatch did not produce a signal above the background noise.
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.
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.
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: Nanoscale light-emitting diodes with colors spanning from the ultraviolet to near-infrared region of the electromagnetic spectrum were prepared using a solution-based approach, which could enable a range of integrated sensor/detection "chips" with multiplexed analysis capabilities.
Abstract: Nanoscale light-emitting diodes (nanoLEDs) with colors spanning from the ultraviolet to near-infrared region of the electromagnetic spectrum were prepared using a solution-based approach in which emissive electron-doped semiconductor nanowires were assembled with nonemissive hole-doped silicon nanowires in a crossed nanowire architecture. Single- and multicolor nanoLED devices and arrays were made with colors specified in a predictable way by the bandgaps of the III-V and II-VI nanowire building blocks. The approach was extended to combine nanoscale electronic and photonic devices into integrated structures, where a nanoscale transistor was used to switch the nanoLED on and off. In addition, this approach was generalized to hybrid devices consisting of nanowire emitters assembled on lithographically patterned planar silicon structures, which could provide a route for integrating photonic devices with conventional silicon microelectronics. Lastly, nanoLEDs were used to optically excite emissive molecules and nanoclusters, and hence could enable a range of integrated sensor/detection "chips" with multiplexed analysis capabilities.
TL;DR: In this article, Li et al. presented new interstellar dust models which have been derived by simultaneously fitting the far ultraviolet to near infrared extinction, the diffuse infrared emission, and, unlike previous models, the elemental abundances in dust for the diffuse interstellar medium.
Abstract: We present new interstellar dust models which have been derived by simultaneously fitting the far ultraviolet to near infrared extinction, the diffuse infrared emission, and, unlike previous models, the elemental abundances in dust for the diffuse interstellar medium We found that dust models consisting of a mixture of spherical graphite and silicate grains, polycyclic aromatic hydrocarbon (PAH) molecules, in addition to porous composite particles containing silicate, organic refractory, and water ice, provide an improved t to the UV-to-infrared extinction and infrared emission measurements, while consuming the amounts of elements well within the uncertainties of adopted interstellar abundances, including B star abundances These models are a signicant improvement over the recent Li & Draine (2001, ApJ, 554, 778) model which requires an excessive amount of silicon to be locked up in dust: 48 ppm (atoms per million of H atoms), considerably more than the solar abundance of 34 ppm or the B star abundance of 19 ppm
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.
TL;DR: In this paper, the positions and orientations of donor and acceptor materials are determined during growth by organic vapour-phase deposition (OVPD5), eliminating contorted and resistive conducting pathways while maximizing the interface area.
Abstract: The power conversion efficiency of organic photovoltaic cells has increased with the introduction of the donor–acceptor heterojunction that serves to dissociate strongly bound photogenerated excitons1. Further efficiency increases have been achieved in both polymer2,3 and small-molecular-mass4 organic photovoltaic cells through the use of the bulk heterojunction (BHJ), where the distance an exciton must diffuse from its generation to its dissociation site is reduced in an interpenetrating network of the donor and acceptor materials. However, the random distribution of donor and acceptor materials in such structures can lead to charge trapping at bottlenecks and cul-de-sacs in the conducting pathways to the electrodes. Here, we present a method for growing crystalline organic films into a controlled bulk heterojunction; that is, the positions and orientations of donor and acceptor materials are determined during growth by organic vapour-phase deposition (OVPD5), eliminating contorted and resistive conducting pathways while maximizing the interface area. This results in a substantial increase in power conversion efficiency compared with the best values obtained by 'random' small-molecular-weight BHJ solar cells formed by high-temperature annealing, or planar double heterojunction photovoltaic cells using the same archetypal materials systems.
TL;DR: In this article, a tensile Si nitride-capping layer is used to introduce tensile uniaxial strain into the n-type MOSFET and enhance electron mobility.
Abstract: Strained-silicon (Si) is incorporated into a leading edge 90-nm logic technology . Strained-Si increases saturated n-type and p-type metal-oxide-semiconductor field-effect transistors (MOSFETs) drive currents by 10 and 25%, respectively. The process flow consists of selective epitaxial Si/sub 1-x/Ge/sub x/ in the source/drain regions to create longitudinal uniaxial compressive strain in the p-type MOSFET. A tensile Si nitride-capping layer is used to introduce tensile uniaxial strain into the n-type MOSFET and enhance electron mobility. Unlike past strained-Si work: 1) the amount of strain for the n-type and p-type MOSFET can be controlled independently on the same wafer and 2) the hole mobility enhancement in this letter is present at large vertical electric fields, thus, making this flow useful for nanoscale transistors in advanced logic technologies.
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 paper, a review relates to the models describing the structural evolution of calcium silicate hydrate (C-S-H) at the crystal-chemical level as a function of composition in terms of calcium to silicon ratio.
TL;DR: The observed oscillatory behavior of the superconducting transition temperature when the film thickness was increased by one atomic layer at a time suggests the possibility of modifying superconductivity and other physical properties of a thin film by exploiting well-controlled and thickness-dependent quantum size effects.
Abstract: We have fabricated ultrathin lead films on silicon substrates with atomic-scale control of the thickness over a macroscopic area. We observed oscillatory behavior of the superconducting transition temperature when the film thickness was increased by one atomic layer at a time. This oscillating behavior was shown to be a manifestation of the Fabry-Perot interference modes of electron de Broglie waves (quantum well states) in the films, which modulate the electron density of states near the Fermi level and the electron-phonon coupling, which are the two factors that control superconductivity transitions. This result suggests the possibility of modifying superconductivity and other physical properties of a thin film by exploiting well-controlled and thickness-dependent quantum size effects.
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.
TL;DR: Similar mass spectra and atomic structures in CdS, CdTe, ZnS and ZnSe are found, demonstrating that mass-specified and macroscopically produced nanoparticles, which have been practically limited so far to elemental carbon1, can now be extended to a vast variety of compound systems.
Abstract: Nanoparticles under a few nanometres in size have structures and material functions that differ from the bulk because of their distinct geometrical shapes and strong quantum confinement. These qualities could lead to unique device applications. Our mass spectral analysis of CdSe nanoparticles reveals that (CdSe)(33) and (CdSe)(34) are extremely stable: with a simple solution method, they grow in preference to any other chemical compositions to produce macroscopic quantities. First-principles calculations predict that these are puckered (CdSe)(28)-cages, with four- and six-membered rings based on the highly symmetric octahedral analogues of fullerenes, accommodating either (CdSe)(5) or (CdSe)(6) inside to form a three-dimensional network with essentially heteropolar sp(3)-bonding. This is in accordance with our X-ray and optical analyses. We have found similar mass spectra and atomic structures in CdS, CdTe, ZnS and ZnSe, demonstrating that mass-specified and macroscopically produced nanoparticles, which have been practically limited so far to elemental carbon, can now be extended to a vast variety of compound systems.
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.