bluuebunny/crossref_metadata_2025_split huggingface dataset:
Minority Carrier Lifetime Studies in Halogen Lamp Recrystallized Soi Films
Authors: Chantre A. , Ronzani D. , Vu D. P. 
Published: March 2011

ABSTRACTWe report a detailed investigation of minority carrier generation processes in halogen lamp recrystallized SOI films. Various kinds of materials have been analyzed in order to assess the roles of the different crystallographic imperfections present in the layers (precipitates, subgrain boundaries, interfaces). We conclude that generation lifetimes inprecipitate-free material are controlled by subgrain boundaries, and show that 100 μs lifetimes can be measured in defect-free regions of SOI obtained using a defect localization technique.
An Analytical Model for the Threshold Voltage of Polysilicon Mosfet's
Authors: Anwar A.F.M. , Khondker A.N. 
Published: March 2011

ABSTRACTAn analytical model is developed to describe quantitatively the increase in the threshold voltage of n-channel polysilicon (poly-Si) MOSFET's. The model takes into account charge-coupling between the gate and grain boundary traps. This charge-coupling appears in Poisson's equation and a charge neutrality equation. A drift-diffusion mode of conduction is used to describe the turn-on characteristics that occur beyond the strong inversion threshold.
Dependence of A-Si:H Tfts Performances on Deposition and Process Parameters
Authors: Chartier E. , Szydlo N. , Boulitrop F. , Proust N. , MagariÑO J. 
Published: March 2011

ABSTRACTAmorphous silicon TFTs have been realized using several plasma-CVD systems which differ in the conception of the reactor: hot or cold walls, and from the frequency used: 400 kHz and 13.56 MHz. Silicon nitride has been used as insulator. Inverted and direct staggered structures with different channel dimensions (0.5 ≤ W/L ≥ 20) are compared. High performance TFTs with mobility from 0.5 to 0.7 cm2V−1s−1 for inverted and from 0.1 to 0.4 cm2V−1s−l for direct staggered TFTs have been optimized by a full study of the insulator semiconductor and source/drain contact properties.
Photoluminescence and Photoconductivity Studies on a-Si:H
Authors: Mendoza-Alvarez Julio G. , Torres Gerardo , Gonzalez-Hernandez J. 
Published: March 2011

ABSTRACTIt has been previously reported that intense illumination on a-Si:H induces luminescence fatigue. The effect of light soaking on the photoconductivity of this material is also known. In this work, studies of photoluminescence (PL) at 10°K shows that the intensity of the main peak at 1.3eV can be correlated with the decrease in the photoconductivity (PC) of the sample. Similar to the PC, the effects of light soaking on the PL spectrum are reversible; annealing at 200°C fully restore the PL spectrum. Our results indicate that the light-induced radiative defects are also involved in the carrier recombination mechanism. By measuring the PL spectrum at temperatures in the range from 10 to 120°K, the activation energy for the non-radiative process has been determined in both light-soaked and heat-dried states.
Improvement of Wetting of Silicon on Insulator During Lamp Zone Melting Using Plasma Nitridation
Authors: Haond M. , Dutartre D. , Pantel R. , Straboni A. , Vuillermoz B. 
Published: March 2011

ABSTRACTIn the preparation of SOI films by Zone Melting Recrystallization (ZMR) a cap layer is necessary to avoid the beading up of a silicon film when it is molten over silicon. This is a consequence of a bad wetting of liquid Si on SiO2. We report the successful application of a plasma nitridation treatment of the capping oxide. We compare the behaviour of the liquid silicon films during ZMR for different capping structures. The modification of the interface is investigated by using Auger analysis. We show that a range of nitrogen accumulation at the interface provides a good wetting.
Large Grain Growth of Silicon Films on Low Temperature Glass Substrates
Authors: Bleil C. E. , Troxell J. R. 
Published: March 2011

ABSTRACTArgon laser recrystallization of silicon films deposited on low temperature glass substrates offers the potential for development of large scale matrix addressable displays incorporating on-glass line drivers and logic circuitry. In order to achieve this promise, the challenge of containing molten silicon, at 1685 K, in close proximity to a glass substrate (Corning 7059) which has an annealing temperature of 914 K, must be met. We have successfully recrystallized areas of several squared millimeters of 500 nm thick silicon films without cracking on 7059 glass substrates. This was achieved by the incorporation of multiple film layers interposed between the silicon and the glass substrate, which serve to control the thermal gradients which occur during the recrystallization process. Grains in the recrystallized films are typically 10µm wide and several hundred µm long, achieved using a laser spot size of approximately 70 µµµµm diameter and a scan rate of 15 cm/s. Comparable results were obtained for a wide range of laser powers, from 7.5 to 9.2 W.
Crystallization Of Amorphous Silicon During Thin Film Gold Reaction
Authors: Hultman Lars G. , Psaras P. A. , Hentzell H.T.G. 
Published: March 2011

ABSTRACTThe crystallization of α-Si in α-Si(50nm) and Au(5nm) thin film bi-layers has been investigated during heat treatment in a transmission electron microscope (TEM). When crystallization of α-Si first begins at 130°C the Au-Si alloy reflections observed at lower temperatures vanish and several new reflections from metastable Au-Si compounds occur. Dendritically growing islands of poly-Si are observed after heating at 175°C. If the samples are held constant at 175°C for ten minutes, the poly-Si islands grow together. The formation of poly-Si depends on the diffusion of Au into α-Si and the formation of metastable Si-Au compounds. After crystallization Au segregates to the front and back surface of the poly-Si film.
Interfacial Reactions Between Amorphous W-Si Thin Films And Polycrystalline Overlayers
Authors: Thomas R. E. , Perepezko J. H. , Wiley J. D. 
Published: March 2011

ABSTRACTInteractions between amorphous metal thin films and either a substrate or an overlayer can limit their effectiveness as diffusion barriers. We have found in previous studies that Au and Al polycrystalline thin films in contact with amorphous W-Si lowers the crystallization temperature of the a-(W-Si) by at least 100C. In contrast Cu and Mo have no apparent effect on the stability of the amorphous layer. The mechanisms leading to premature crystallization are not well understood. Amorphous W .72Si.28 was deposited by D.C. sputtering onto single crystal Si substrates. Overlayers of Al were then evaporated onto the W-Si. Using Auger electron spectroscopy depth profiling coupled with cross-section TEM, we have studied interfacial reactions between the amorphous layer and polycrystalline Al. Auger profiling results show that in the case of Al overlayers, W and Si diffuse out of the a-(W-Si) into the Al where WAl12 forms. These results can be explained in the context of three binary diffusion couples, W-Si, W-Al, Al-Si, and the individual interactions associated with these couples.
Bombardment-Induced Mixing of Mo Films on Si
Authors: Van Ommen AH. , Willemsen M.F.C. , Boudewijn PR. , Reader A. H. 
Published: March 2011

ABSTRACTWe studied ion beam mixing of thin Mo films on monocrystalline Si by As “implantation at room temperature. The results differ significantly from those obtained for implantation at elevated temperature (T > 200°C). where ion beam mixing results in hexagonal MoSi2 formation. Room temperature implantation results in the formation of an amorphous mixed layer. The composition of this layer varies with depth from Mo-rich to Si-rich. The mixed layer thickness increases linearly with implanted dose and energy. An increase of the implantation temperature with 100°C gives rise to a factor of 2 larger mixed layer thickness and to the formation of amorphous MoSi2 near the interface with Si. These phenomena indicate that at elevated temperature ion beam mixing is controlled by radiation-enhanced diffusion whereas, at room temperature ballistic mixing is the dominant mechanism.
Epitaxial Formation of Rare Earth Silicides by Rapid Annealing
Authors: Knapp J. A. , Picraux S. T. 
Published: March 2011

ABSTRACTRapid electron beam and lamp heating have been used to form thin epitaxial films of rare-earth suicides by reacting overlayers of the rare earths with (111) Si substrates. Of the metals Y, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu, all but Gd are found to form epitaxial suicide layers by rapid solid-phase reaction, while suicides of Gd, Dy, Tm, Yb and Lu have been formed epitaxially by liquid phase reaction. For all but Er this is the first demonstration of epitaxial growth on Si. Details obtained from ion beam channeling analysis and transmission electron microscopy confirm the expected epitaxial structure and also show that the Si vacancies in the suicide form an ordered superlattice, rather than a random array as had been assumed before.
Formation Of Stacking Fault Tetrahedra During Epitaxial Growth of Silicon and Germanium-Silicon Layers on {111} Silicon Substrates
Authors: Brasen D. , Nakahara S. , Bean J. C. 
Published: March 2011

ABSTRACTTransmission electron microscopy was used to characterize defects formed in silicon (Si) and germanium-silicon (Ge-Si) alloy layers grown sequentially by molecular-beam epitaxy (MBE) on {111} Si substrates. Stacking fault tetrahedra (SFT) were found to form in these epitaxial layers. In addition, the apex of the SFT are seen to be pointing down toward the Si substrate, with most of the SFT tips converging exactly at the Si/Si and the Ge-Si/Si interfaces. Diffraction contrast experiments using various two-beam conditions have shown that the stacking faults bounding the SFT are of intrinsic (vacancy) type. In the case of a Si layer on the Si substrate, it is reasoned that the SFT are caused by impurities on the surface of the Si substrate prior to deposition. However, in the Ge-Si layer, it is believed that the formation of the S FT is due to local stresses caused by the structural ordering/phase separation of the Ge atoms.
The Electronic Properties of Epitaxial Calcium Fluoride-Silicon Structures
Authors: Smith T. P. , Phillips J. M. , People R. , Gibson J. M. , Pfeiffer L. , Stiles P. J. 
Published: March 2011

ABSTRACTThe characterization of electronic devices using epitaxial CaF2 on Si is described. In addition, the growth and annealing techniques used to obtain high quality epitaxial films are discussed. In particular, the results of using rapid thermal annealing to improve the epitaxial quality of CaF2 films are presented in detail.The electronic and electrical properties of these structures are very promising. Epitaxial CaF2 films with breakdown fields as high as 3 × 106 V/cm and interface trap densities as low as 7 × 1010cm-2eV-1 have been fabricated. In addition, minority carrier dominated trapping has been observed at the CaF2 /Si interface. Finally, the material properties of these structures, as determined by Rutherford backscattering, channeling, and electron microscopy, are discussed and correlated with their electronic properties.
MBE Growth of an Epitaxial Insulator-Metal-Semiconductor Structure: CaF2/CoSi2/Si(111)
Authors: Phillips Julia M. , Augustyniak W. M. 
Published: March 2011

ABSTRACTWe report the first successful growth of an epitaxial insulator-metal-semiconductor structure. A layer of metallic CoSi2, followed by a layer of insulating CaF2 have been grown by molecular beam epitaxy on Si(111). The epitaxial quality of the CaF2 layer improves upon rapid thermal annealing, while the already excellent crystallinity of the CoSi2 layer is unaffected. The lattice of the CoSi2 is rotated 180° with respect to the Si lattice while the CaF2 lattice is aligned with the Si lattice.
Theimddynamically Stable Metal / III-V Compound-Semiconductor Interfaces
Authors: Stanley Williams R. , Lince Jeffrey R. , Tsai Thomas C. , Pugh John H. 
Published: March 2011

ABSTRACTChemical reactions that occur at a metal/III-V compound-semiconductor interface should be minimized if the change in Gibbs free energy of the bulk materials with respect to any possible reaction products is positive. However, the large positive change in entropy caused by vaporization of the highly volatile group V elements is a very important contribution to the Gibbs free energy of these systems, especially at higher temperatures. Thus, a particular metal/III-V compound-semiconductor interface may be thermody-namically stable at one temperature, but unstable with respect to sublimation of elemental group V species at a higher temperature if the enthalpy change for the reaction is positive. Examination of bulk phase diagrams makes it possible to rationalize the reaction products observed and to predict which will be the most stable interface for any particular metal/III-V system.
First Phase Nucleation And Growth Of Titanium Disilicide With An iPhasis On The Influence Of Oxygen
Authors: Van Houtum Harrie J. W. , Raaijmakers Ivo J. M. M. 
Published: March 2011

ABSTRACTThe existence of a TiSi2phase in the C49 (ZrSi2) structure prior to formation of the stable low resistivity C54 TiSi2structure has been justified for Ti-Si thin film diffusion couples after low temperature (500°C to 650°C) anneal. The transition temperature (Ttr) to the C54 phase is shown to be dependent on layer thickness, thinner films yielding higher Ttr. We could not detect an influence of oxygen on Ttr. Moreover the growth rate of C49 TiSi2is independent of oxygen contamination in the Ti layer up to a mean concentration of 23 at.%. It is postulated that the transition from the C49 to the C54 phase actually is a recrystallization process.
Interface States at Au/Gaas Schottky Contacts
Authors: Werner J. , Ploog K. 
Published: March 2011

ABSTRACTWe present a new method for the characterization of traps at the interfacial layer of metal/semiconductor contacts. The method is based on measurements of the ac-admittance of Schottky contacts over a wide frequency range. The frequency dependence is analyzed within a new Trap Transistor Model which explains the ac-behavior as well as the dc-characteristics. In particular we propose that the ac-current across the interface consists of capacitive as well as of conductive parts. We are able to deduce the density of trap states at the majority carrier Fermi level as well as the capture cross section of the traps. The model is applied to Au/GaAs-Schottky contacts. We find a weak energy dependence for the density of interface states as well as for their capture cross section within the energy range of 0.45eV to 0.57eV below the conduction band edge.
Refractory Silicide Schottky Contacts To Gaas
Authors: Yokoyama N. , Ohnishi T. , Nakamura T. , Nishi H. 
Published: March 2011

ABSTRACTRefractory suicides form high temperature stable Schottky contacts to GaAs. This finding enabled us to develop self-aligned GaAs MESFETs, thereby enabling the development of today's GaAs ICs. This paper reviews electrical and metallurgical studies on refractory-metal/GaAs and refractory-metal-si licide/GaAs interfaces. We emphasize the fact that W5Si3/GaAs contacts have extremely stable electrical properties even after annealing at temperatures up to 850°C. Crystallographical properties of the W5S3 film on GaAs, investigated by x-ray and TEM measurement techiques, are also covered. We found that the Schottky electrical characteristics are not affected by whether the film is amorphous or crystalline.
Interface Reactions and Electrical Behaviour of Ni-AuGe Contacts on GaAs
Authors: Botha A P , Relling E 
Published: March 2011

ABSTRACTInterdiffusion and reaction in the GaAs/AuGe/Ni and GaAs/Ni/AuGe/Ni thin film systems have been investigated, using Auger Electron Spectroscopy depth profiling and Rutherford Backscattering Spectrometry. The roles of the individual metal layers were determined by studying the GaAs/AuGe, GaAs/Ni and GaAs/Ni/AuGe subsystems. It was found that the interfacial layer in the GaAs/Ni/AuGe/Ni contact scheme prevents Ge from diffusing away from the interface. In this way more efficient doping of the GaAe is possible. Current-Voltage measurements indicate that this layer structure forms a good ohmic contact to GaAs.
The Phase Formation Sequence In Titanium-Silicon Thin Films
Authors: Beyers Robert , Sinclair Robert 
Published: March 2011

ABSTRACTThe reliable use of TiSi2 in integrated circuit metallizations will depend in part on an intimate knowledge of the effects of processing variables — such as annealing time, temperature, and ambient — on the phase formation sequence. For this reason, transmission electron microscopy has been used to investigate the formation of TiSi2 thin films on silicon substrates [1]. For films formed either by reacting titanium with a silicon substrate or by sintering a codeposited (Ti + 2 Si) mixture, we find that a high resistivity (∼60 μΩcm), metastable phase — TiSi2(C49 or ZrSi2 structure) — forms prior to the desired low resistivity (∼15 μΩcm), equilibrium phase — TiSi2(C54 structure). In titanium-silicon diffusion couples, a thin layer of TiSi is also present on top of the metastable TiSi2- For processing temperatures above 550°C, the available data suggest that the metastable TiSi2 forms first and acts as a template for subsequent nucleation of the TiSi phase. In codeposited (Ti + 2 Si) films, TiSi2(C49 structure) is the only intermediate phase. The temperature at which the C49 structure transforms to the C54 structure increases significantly as the film impurity content increases. Differences in earlier reports of TiSi2 formation [2–5] appear to be resolved if x-ray diffraction peaks attributed to Ti5Si3 and TiSi were actually from the metastable TiSi2
Microscopic Model of Metal-Semiconductor Contacts and Semiconductor Heterojunctions
Authors: Mailhiotand C. , Duke C. B. 
Published: March 2011

ABSTRACTA microscopic many-electron model is utilized to calculate the self-consistent one-electron potential in the vicinity of a metal-semiconductor or semiconductor-semiconductor interface. The boundary conditions ensuring thermal, mechanical and electron-transfer equilibrium are imposed explicitly. Numerical calculations predict the validity of Schottky's phenomenological boundary condition for metal-semiconductor contacts and the applicability of the electron affinity rule for semiconductor heterojunctions. The occurrence of interfacial atomic rearrangements and/or chemical reactions is incorporated into the model via the inclusion of charge centers near the interface.
Electrical Transport in thin Silicide Films
Authors: Hensel J. C. 
Published: March 2011

ABSTRACTThis paper reviews our recent studies of electrical transport in thin suicide films. Resistivity as a function of temperature, Hall effect, and magnetoresistance have been characterized for CoSi2 and NiSi2 and in conjunction with band theory provide estimates of important electronic parameters, viz. carrier densities and carrier scattering lengths. Resistivity data for TiSi2 and TaSi2 are included. Also examined in resistivity are (i) effects produced by ion bombardment which show CoSi2 to have an unusual susceptibility to radiation damage and (ii) classical size effects in the very thin film regime which show the boundary scattering to be principally specular. As an application we describe a Si/CoSi2/Si heterostructure transistor recently developed.
Crystallization Of Amorphous Tungsten Disilicide. Stacking Faults And Resistivity
Authors: LeGoues F. K. , d'Heurle F. M. , Joshi R. , Suni Ilka 
Published: March 2011

ABSTRACTFilms of WSi, have been investigated by electron microscopy after annealing at different temperatures. It is shown that films annealed at 550°C contain a high density of stacking faults. The crystalline identity of these stacking faults has been established. Undoubtedly the high density of stacking faults is the cause of the resistivity maximum observed in films annealed at 550°C.
Implantation Induced Charge Trapping and Interface States Generation in Si-SiO2 System
Authors: Wong H. , Cheung N. W. 
Published: March 2011

ABSTRACTConstant-voltage stressing has been used to investigate the damage of SiO2 and the Si/SiO2 interface induced by silicon implantation through polysilicon/SiO2/P-Si structures annealed at 950°C. The implant doses used were from 5×1011cm-2 to 1014cm-2. Although no detectable interface states density was observed after the annealing for implant doses less than 2×1013cm-2, interface states generation, hole trapping, and electron trapping were found to be greatly enhanced by the Si implantation. The interface states density generation rate was found to increase with higher implant doses. The density of hole trapping centers saturated at a value of 3×1012cm-2 for implant doses higher than 2×1012cm∼-2. The density of electron trapping centers was found to increase with implant dose, while the associated trapping cross section was much smaller than that of the unimplant oxide.
The Oxidation Behavior of the √3×√3 Ag and Au/Si(111) Surfaces at Room Temperature Studied by Photoemission
Authors: Yeh J. J. , Friedman D. J. , Cao R. , Hwang J. , Nogami J. , Lindau I. 
Published: March 2011

ABSTRACTThe differences of the room temperature oxidation behavior of ordered Ag/Si(111) and Au/Si(111) surfaces were studied by surface sensitive soft x-ray photoemission spectroscopy obtained with synchrotron radiation. Si surfaces covered with a monolayer of Ag or Au, once annealed to display a √3×√3 LEED pattern, were believed to be passivated against oxidation according to earlier reports. This work shows that these two surfaces oxidize but in a different way. Up to 104 L O2 exposures, the observed valence band of the Au/Si surface's valence band electron energy distribution curve is almost identical to that of the surface before oxygen exposure. But the corresponding Si 2p core level spectrum shows a small chemically shifted component indicating an initial stage of the formation of Si oxide. Thi3 chemically shifted signal becomes a strong peak at -3.7 eV below the clean Si position, characteristic of SiO2, after subsequent O2 exposures up to 1010 L. The Ag/Si system behaves in a similar fashion, but oxide growth saturates at 108 L, and the final oxides formed include a distribution of suboxides in addition to SiO2. Clearly, oxide formation is not prohibited by the presence of the ordered Au or Ag metal overlayer but delayed. Although the onset of oxidation is delayed compared to that for the clean Si surface, due to the metal-silicon bonding, the oxide formation is much faster once the surface starts to oxidize.
Dopant Redistribution During Silicide Formation
Authors: Ohdomari I. , Konuma K. , Takano M. , Chikyow T. , Kawarada H. , Nakanishi J. , Ueno T. 
Published: March 2011

ABSTRACTAfter the review of dopant redistribution phenomena observed during formation of near noble metal suicides, we describe the results of our recent experiments to get a better understanding of a mechanism of the dopant redistribution phenomenon in Si substrates. The key factors to understand the dopant redistribution are dopant segregation at the suicide/ Si interface due to lower solubility limit of dopants in suicides, enhanced diffusion of dopants into the Si substrate at much lower temperatures than the ordinary thermal diffusion, and electrical activation of the redistributed dopants. The results of As and carrier concentration measurements before and after Pd2Si formation to make clear the third factor show that the electrical activity of the redistributed As atoms in Si is strongly dependent on the initial activity before Pd2Si formation which is controlled by the temperature for the pre-annealing of As implanted Si.Shrinkage of extrinsic dislocation loops introduced by As implantation and subsequent annealing have been observed after Pd2Si formation, which is a good evidence of vacancy generation during Pd2Si formation. The role of the vacancies and interstitials on the second factor, the enhanced diffusion, has also been discussed. Finally we list a few issues to be answered in future by more detailed works in order to get a complete understanding of the redistribution phenomenon.