bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dopant Diffusion and Grain Growth in Arsenic-Implanted Poly-Si
Authors: Zheng L. R. , Hung L. S. , Mayer J. W. 
Published: March 2011

ABSTRACTThe diffusion behavior of arsenic and the grain growth of Si in arsenic doped poly-Si were investigated by MeV4 He2+ backscattering techniques and transmission electron microscopy. By implanting arsenic ions into poly-Si films the surface portion was made amorphous and crystallized upon annealing. In-situ mssurements showed crystal nucleation and growth at temperatures of 650 – 700° C with a dimension comparable to the thickness of the amorphous layer. Annealing at temperatures up to 850°C increased the number of the large grains, but the average grain size did not change significantly. In the unimplanted region grains retained their initial size until 885°C, although implanted arsenic was found to diffuse into this region along grain boundaries. At 885°C penetration of arsenic into the interior of grains caused significant grain growth. We also found that single implants of boron somewhat increased grain size, whereas boron codoped with arsenic appeared to reduce the effect of arsenic doping. These observations support the hypothesis that the enhanced growth rate and the electrical activity of Si near the grain boundary are closely interrelated.
Kinetic Modeling of Grain Growth in Polycrystalline Silicon Films Doped with Phosphorus and Boron
Authors: Kim H.-J. , Thompson C. V. 
Published: March 2011

ABSTRACTIn previous work it has been shown that doping of silicon with P or As leads to enhanced rates of grain growth while doping with B has little effect, except in compensation of the effect of P or As. Here we report a detailed study of the effects of P doping on normal grain growth in silicon films. We also outline a kinetic model for grain growth which is consistent with the various observed effects of dopants. This model is based on the assumption that dopants primarily affect grain boundary mobilities and that grain boundary motion occurs through parallel diffusive and non-diffusive processes. It is further assumed that the rate of the diffusive process is proportional to the vacancy concentration which is a known function of the electron concentration.
Applications of Polysilicon Films in Microsensors and Microactuators
Authors: Howe Roger T. 
Published: March 2011

ABSTRACTThis paper reviews the applications of polysilicon in microsensor technology and in the emerging field of microfabricated actuators. Polysilicon is an attractive material for thin-film strain gauges, and is also used to fabricate micromechanical structures. The need for better understanding of the non-electrical properties of polysilicon, such as Young's modulus, residual strain, ultimate strength, friction, and wear, is emphasized.
Structural and Electrical Properties of Heavily-Doped Rapid-thermal-Processed Polysilicon Emitters and Contacts on Silicon
Authors: Raicu Bruha , Christel L. A. , Huang K.-G. , Hashimoto Shin , Gibson W. M. , Ward I. 
Published: March 2011

ABSTRACTSupersaturated high-conductivity polycrystalline silicon (polysilicon) formed by rapid thermal processing (RTP) is a promising new material for emitters, contacts and diffusion sources in advanced high-speed bipolar and MOS IC technologies.A matrix of processing conditions was used to evaluate the effect of polysilicon thickness, implant dose, RTP conditions and the nature of the substrate on the dopant diffusion in both the polysilicon and single crystal substrate and also on the interface properties.Results of conductivity measurements, spreading resistance profiling (SRP), secondary ion mass spectroscopy (SIMS), transmission electron microscopy (TEM) and Rutherford backscattering spectroscopy (RBS)/channeling are presented. The results have proved the formation of shallow, defect-free junctions and epitaxial emitters with low series resistance and improved contact properties.
Characterization of Arsenic Implanted Epitaxially Aligned Polysilicon-on-Silicon Films
Authors: Hoyt J. L. , Crabbé E. F. , Pease R. F. W. , Gibbons J. F. 
Published: March 2011

ABSTRACTNonuniformities in the polysilicon-to-silicon interface and in the polysilicon structure are expected to produce a nonuniform diffusion front when arsenic is diffused from polysilicon during epitaxial alignment. Using transmission electron microscopy, we find surprisingly uniform arsenic diffusion fronts in the underlying silicon substrate following high temperature annealing. Several explanations of this result are proposed. We also report new evidence of a strong reduction in the time to achieve complete epitaxial transformation of the polysilicon when the polysilicon thickness is reduced. A corresponding reduction in the associated arsenic penetration depth is demonstrated.
Picosecond Optical Determination of Carrier Lifetime in Polysilicon Films
Authors: Bambha N. K. , Nighan W. L. , Campbell I. H. , Fauchet P. M. , Johnson N. M. 
Published: March 2011

ABSTRACTThe lifetime of optically injected carriers is determined in polySi/SiO2/Si structures grown by LPCVD at 625°C. These samples are as-grown, have undergone H diffusion or have been implanted by phosphorous ions, followed by various annealing schedules. The lifetime measurement is done in an all-optical, contactless fashion, using the tools of picosecond time-resolved spectroscopy. We find that the lifetime due to recombination at the grain boundaries (trapping time) increases after implantation only if subsequent annealing increases the grain size. The trapping time also increases after hydrogen diffusion. After trapping in relatively shallow grain boundary states, thermalization into deeper lying states is slow on a subnanosecond time scale.
Low Temperature Annealing of LPCVD Silicon Films
Authors: Aoyama T. , Konishi N. , Suzuki T. , Miyata K. 
Published: March 2011

ABSTRACTLow temperature, 600°C annealing of LPCVD films was investigated by x-ray diffraction, ESR, TEM, and carrier mobility measurements. An optimum deposition temperature of about 550°C was found to yield good crystallinity and large electron mobility for annealed films; large grain sizes, a maximum crystallite size, and a maximum electron spin density were also observed for films deposited at the optimum temperature. Electron spin density for as-deposited films correlated with the crystalline volume by x-ray diffraction measurements on the films after annealing. This implys that only those amorphous components with high electron spin density can be converted into the crystalline phase by 600°C annealing.
Effects of Hydrogenation on the Off-State of Polysilicon Thin Film Transistors
Authors: Khan Babar A. , Pandya Ranjana 
Published: March 2011

ABSTRACTWe have carried out transient photoconductivity experiments on hydrogenated and unhydrogenated polysilicon Thin Film Transistors (TFTs) which indicate that the primary effect of plasma hydrogenation is the reduction by several orders of magnitude of the band tail trapping states. A smaller effect is a reduction of the dangling bond density by a factor of 2 or 3 as indicated by Electron Spin Resonance (ESR) measurements. Since the dangling bond is associated with the generation/recombination center, it may not be obvious how such a small reduction in generation/recombination center density leads to over 2 orders of magnitude reduction in off-state current of the TFTs. In this paper, we describe how the large reduction of band tail states can lead to significant reduction of carrier generation near the contacts despite the fact that the generation/recombination center density is not changed significantly. This reduction of carrier generation leads to the observed reduction in off-state currents.
Quantum Size Effect in Polysilicon Gates
Authors: Lifshitz N. , Laryi S. , Sheng T. T. 
Published: March 2011

ABSTRACTIt has been observed by several authors that metal-oxide-semiconductor devices with polycrystalline Si (polySi) gates behave differently depending on the doping species in polySi: the work-function difference between the silicon substrate and the gate (øps) is higher when the gates are doped with arsenic than when they are doped with phosphorus.We believe that the different behavior of øps. can be explained by different grain textures at the polySi/SiO2 interface. Our transmission electron microscoey of the films indicates that while P-doped material consists of large (≈3000Å) grains, As-doped polySi preserves its as-deposited columnar structure – even after a high temperature anneal. Moreover, at the interface with the gate oxide an as-deposited microstructure with very small (≈100Å) “embrionic” grains is preserved. On the basis of these observations, we suggest a model for the different behavior of ø ps. The model is based on a quantum-size effect which becomes important for such small grain dimensions at the interface in As-doped polySi. This effect drastically reduces the number of states available in the conduction band at low energies. The resulting shift of the Fermi level provides a qualitative explanation for the observed puzzling difference between the work-functions of Asand P- doped polySi.
Electrical and Electronic Properties of Grain Boundaries in Silicon
Authors: Queisser Hans J. , Werner Jorgen H. 
Published: March 2011

ABSTRACTThe electronic states at silicon grain boundaries trap preferentially majority carriers, thus cause a potential barrier impeding current flow. We here summarize measurement techniques for the energy distribution of these grain boundary traps. The analysis reveals band tails due to disorder in the boundary plane as well as interface state continua at midgap. The spatial distribution of trapped charges results in significant electrostatic potential fluctuations which are observable in ac-admittance and noise experiments; the charge fluctuations cause in particular 1/f-like noise. The naive model of dangling bonds to describe grain boundary charges is insufficient, impurity atoms, especially oxygen, play essential roles in determining electronic behavior.
Structural and Electrical Properties of Molecular Beam Deposited Polycrystalline Silicon
Authors: Delage Sylvain L. , Jeng S.-J. , Jousse D. , Iyer S. S. 
Published: March 2011

ABSTRACTThe structural and electrical properties have been investigated of antimony doped polycrystalline silicon films obtained by molecular beam deposition on oxidized silicon substrates. We show that low resistivity films with smooth morphology are obtained by Solid Phase Crystallization of antimony doped amorphous silicon layers deposited at 250°C. A resistivity of 4.3 mΩ cm is obtained by crystallizing the films at temperatures as low as 650°C for 15 minutes. Similar resistivities are typically obtained by Chemical Vapor Deposition at temperature of at least 850 °C. In-situ crystallization of the amorphous silicon is needed to obtain low resistivity polysilicon. We also show that direct deposition above 650 ° C gives rise to polycrystalline silicon with much higher resistivities.
Interaction of Deuterium with Buried Oxides in Silicon
Authors: Myers S. M. 
Published: March 2011

AbstractSilicon with buried oxides formed by ion implantation (SIMOX) or zone-melt recrystallization (ZMR) was exposed to deuterium gas at temperatures from 773 K to 1273 K, and the depth profile of the D was then determined by nuclear-reaction analysis. The D was localized within the buried oxide, with no measurable quantity in the Si phase. Uptake was controlled by permeation through the Si overlayer, and the permeability of D in Si was determined at 873 K. The sample dependence of D uptake indicated substantially fewer defect-trap sites in SIMOX oxide annealed at 1678 K as opposed to 1548 K, with still smaller defect densities in the ZMR oxide. Hydrogen exposure at 1273 K substantially disrupted the SIMOX structures.
Zone-Melt-Recrystallization of Silicon-On-Insulator Films Using a Dual-Lamp Apparatus
Authors: Ramesh S. 
Published: March 2011

AbstractWe have studied the recrystallization of silicon films using a focused dual-lamp apparatus. By careful measurement and control of the power density profile (and focal-plane location) of the line-image and of the uniformity of the substrate temperature we have achieved recrystallization of SOI films on 4“silicon wafers. By taking advantage of the measured difference in power-density-profiles of an arc lamp and a tungsten lamp in the dual-lamp apparatus we have achieved low temperature-gradient, reduced-stress recrystallization yielding SOI films in which the usual branched pattern of subgrain-boundaries are replaced by individual dislocations. In situ study of the melt- and growth-fronts, was done using a viewing system with a resolution of - 10 ¼m. We have also done studies of stress-relief schemes.
Layered Structures Composed of Si, Ge, GaAs, and Fluorides
Authors: Ishiwara H. , Asano T. , Tsutsui K. , Lee H.C. , Furukawa S. 
Published: March 2011

AbstractRecent progress in the heteroepitaxial growth of layered structures of Si, Ge, GaAs, and alkaline earth fluorides is reviewed. Effectiveness of the predeposition technique, in which a thin Si layer is deposited on the CaF2 surface at room temperature prior to the growth of a thick Si film at 800 °C, is shown for the growth of Si films on CaF2/Si structures. In case of the overgrowth of Ge and GaAs films on (111) substrates, modification of the fluoride surface by electron beam exposure is effective to increase the wet-tability between fluoride and semiconductor films and to improve the crystal -1 inity and surface morphology of the films. Finally, antiphase disorder in the GaAs(100) films grown on fluorides is experimentally studied and the generation mechanisms are discussed.
Buried Oxide Soi: Materials, Devices, and VLSI Circuits
Authors: Chen C.-E. Daniel , Team Rad-Hard Soi Project 
Published: March 2011

AbstractIn the past couple of years, buried oxide SOI has emerged as the leading SOI approach. Significant advances have been made in the understanding and the preparation of the buried oxide substrates. Various VLSI circuits have been demonstrated with excellent results, proving the maturity and the manufacturability of this technology. In this paper, buried oxide material properties, device parameters and the implementation of a 2.5 urn 4K SRAM and a 1.25 pm 16K SRAM on the buried oxide substrates are reviewed.
Radiation-Induced Oxide Charge Distributions in Simox Buried Oxides
Authors: Hwang J. M. , Bartko J. , Rai-Choudhury P. , Bailey W. E. 
Published: March 2011

AbstractIn ionizing-radiation environments, oxide charge buildup in the buried oxide of SIMOX SOI material causes an increase in the back-channel leakage current, resulting in an instability in electronic circuits formed on SIMOX wafers. We report the measured distributions of radiation-induced oxide charge density in buried oxides formed by oxygen implantation. These are obtained by etch-back experiments including C-V measurements using a mercury probe and ellipsometer measurements. The results show a region of higher charge density about 1500A from the top interface with a lower density region within a few hundred angstroms of the top interface. The results also show that the oxide charge density decreases with annealing temperature. Some unusual optical properties of SIMOX oxide observed in ellipsometer measurements are discussed comparatively with thermal oxide.
Temperature Dependence of Rapid Thermal Annealing of Silicon on Sapphire
Authors: Richmond Eliezer Dovid , Campisi George , Twigg Mark 
Published: March 2011

AbstractThe material improvement of silicon on sapphire by rapid thermal annealing (RTA) is investigated as a function of the maximum temperature during the RTA cycle. Dramatic improvement of the crystalline quality throughout the silicon epilayer occurs for the lowest RTA temperature used (1160°C). The dechanneled fraction at the surface, Xo = 0.033, for the highest temperature anneal, gives bulk-like silicon values. Thus, at the surface, the crystalline quality is like bulk silicon. For the higher temperature anneals, transmission electron microscopy reveals that only a few microtwins extend to the surface. The defect microstructure in the region of the silicon/sapphire interface is substantially reduced. The RTA results in Al autodoping on the order of 1017 cm-3. The strain in the silicon epilayer is the same both before and after the RTA. The defect elimination can be explained in terms of the motion of the incoherent boundaries of the microtwins.
Porosity Determinations in Buried and Surface Layers of Porous Silicon
Authors: Guilinger Terry R. , Kelly Michael J. , Tsao Sylvia S. 
Published: March 2011

AbstractGravimetric techniques offer a convenient and accurate method of determining surface layer porosity in both n- and p-type porous silicon (PS). Porosity of the PS affects its volume expansion on oxidation and the insulating properties of the resulting oxide. Optimal porosity (ca. 55%) yields fully dense, insulating oxides with minimal expansion-induced stresses. Two factors affect the porosity: chemical dissolution of PS by the anodization electrolyte, and oxidation of the PS to produce a native oxide on the surface. Buried layer porosities cannot normally be measured by gravimetric techniques unless the volume of the buried layer is large enough to yield a measurable weight change on anodization. We therefore used a form of Faraday's Law to determine buried layer porosities and determined that they can be correlated with porosities of surface layers formed under identical conditions.
Dissolution and Disintegration of Uniform SiO2 Layers During Direct Silicon Wafer Bonding
Authors: Ahn Kun-Young , Gösele Ulrich , Smith Patrick 
Published: March 2011

AbstractThe conditions for the dissolution and disintegration of SiO2 layers between silicon wafers during direct wafer bonding are discussed in terms of two possible mechanisms. The calculated maximal thickness of a SiO2 layer which may be completely dissolved does not only depend on the bonding temperature and time but also on the starting concentration of interstitial oxygen in the silicon wafers. Finally, the influence of rotational misorientation of the two wafers on the behavior of the S1O2 layers is dealt with.
Molecular Beam Epitaxial Growth of Gaas on Silicon with Buried Implanted Oxides
Authors: Das K. , Humphreys T.P. , Posthill J.B. , Parikh N. , Tarn J. , El-Masry N. , Bedair S.M. , Chu W.K. , Wortman J.J. 
Published: March 2011

AbstractWe report the first results of direct growth of GaAs by molecular beam epitaxy on nominally (100) oriented silicon with buried implanted oxides. Rutherford backscattering and transmission electron microscopy techniques have been used to characterize these layers. The formation of hillocks and a uniform layer of GaAs in the intervening regions between hillocks have been observed. Microtwins, dislocations and antiphase domain boundaries are the predominant defects observed in these layers.
Rapid Thermal Processing of Multiple Low Dose Oxygen Implantations for SIMOX
Authors: Blake J. , Gelpey J. C. , Lee D. M. , Rowland L. , Rozgony G. A. 
Published: March 2011

AbstractA cross-sectional transmission electron microscopy study has been performed on SIMOX wafers prepared using three sequential low dose (6 x 1017 cm2) oxygen implantations. After each implant the wafers were annealed using rapid thermal processing at temperatures up to 1360°C for times of 1 to 5 minutes. The TEM results show that, although low dislocation densities are obtained, oxygen precipitate dissolution is incomplete for these conditions. Therefore, longer annealing times will be required. In addition, lower increments of oxygen dose are recommended to approach dislocation-free superficial silicon layers.
”Nonlinear Optical Materials & DoD Device Requirements”
Authors: Kushner Brian G. , Neff John A 
Published: March 2011

ABSTRACTWithin the past several years, the development of advanced materials with large second and third order nonlinear (X2 and X3) effects has generated interest in developing devices to exploit these properties in military systems of the future. This interest has taken many forms, from the funding of basic research aimed at developing enhanced nonlinear optical effects in materials to the deployment of actual mil-spec devices. Two years ago, at this same forum, we delineated a series of materials performance requirements which, if achieved, would allow device developers to take maximum advantage of these nonlinear effects in such disciplines as optical computing, optoelectronic interconnects and sensor protection. In the interim, DoD requirements for advanced materials and devices have continued to accentuate the need for advanced nonlinear optical materials. This paper will discuss some of the most recent trends in nonlinear optical materials research from a device requirements perspective, including an overview of the results of the recent DARPA forum on nonlinear optical materials and a discussion of future directions. As in the previous paper, we will confine ourselves to three challenging areas: nonlinear optical materials for optical computing applications, materials for computer peripherals and internode communications, and materials for sensor protection.
Optically Nonlinear Films of Amphiphilic Polymers: Synthesis, Langmuir-Blodgett Deposition, and Optical Measurements
Authors: Hall Robert C. , Lindsay Geoffrey A. , Anderson Brian , Kowel Tephen T. , Higgins Brian G. , Stroeve Pieter 
Published: March 2011

ABSTRACTNovel polymers are synthesized by attaching amphiphilic dye groups along a hydrophilic polyether backbone. These polymers are fabricated into noncentrosymmetric films by the Langmuir-Blodgett (L/B) technique. Stacks of molecular bi-layers are assembled by γ-type deposition, interleaving two different dye-substituted polymers. One polymer has the dye's molecular dipole pointing toward the backbone, while in the other polymer, the dye points in the opposite direction. Light from a Nd:YAG laser is passed through these films and the second harmonic is detected.
New Method for the Measurement of Electro-optic Constant of Polycarbonate Films Doped with 4-Diethylamino-4′-Nitrostilbene Molecules
Authors: Uchiki Hisao , Kobayashi Takayoshi 
Published: March 2011

ABSTRACTWe propose a new method for the determination of the electro-optic constant. Third-order nonlinear susceptibility (X(3)(-ω;ω,0, 0)) of polycarbonate films doped with 4-diethylamino-4′-nitrostilbene molecules was determined between 550 and 800 nm at room temperature by using this method. X(3)(-ω;ω0, 0) is (5-4i) × 10-12 esu at 600 nm.
Highly Oriented Unsubstituted Polydiacetylene
Authors: Jorgensen B. , Aldissi M. , Liepins R. , Agnew S. 
Published: March 2011

ABSTRACTHighly oriented, unsubstituted polydiacetylene was obtained by the polymerization of 1,3-butadiyne in perhydrotriphenylene (PHTP). The canal structure of PHTP induces a high degree of order in the polymer. Transparent orange crystals were formed which were shown by SEM to consist of structures oriented parallel to the long axis of the crystal. Resonance Raman and UV-visible spectroscopy indicate the polymer consists of seven to ten conjugated ene-yne type repeat units. Crystallization of the inclusion complex was induced inside glass capillaries so the crystals filled the entire space along the length of the capillary.