bluuebunny/crossref_metadata_2025 huggingface dataset:
Mechanical and Microstructural Properties of Boron Implanted Beryllium
Authors: Kant R. A. , Knudson A. R. , Kumar K.
Published: March 2011

High dose boron implantation into instrument grade 1–400 beryllium has been found to produce a substantial increase of its wear resistance. A comparison of the friction and wear behavior resulting from two shapes of the boron depth distribution is made. The wear resistance provided by a boron layer of constant (flat) concentration was found to be superior to that of a gradually decreasing (graded) profile. Rutherford backscattering was used to determine the boron depth distribution profiles and transmission electron microscopy was used to examine the microstructure. Electron diffraction pattern analysis provides evidence for the formation of beryllium borides.
The Effect of Nitrogen Implantation on Martensite in 304 Stainless Steel
Authors: Vardiman R. G. , Bolster R. N. , Singer I. L.
Published: March 2011

Martensite will form in austenitic 304 stainless steel when it is deformed. Transmission electron microscope studies show that nitrogen ion implantation causes a reversion of the martensite to austenite. Specimens containing martensite resulting from fine surface polishing and heavy rolling are examined. The transformation is shown not to occur because of temperature increases during implantation. The effect is related to recent wear results in 304 stainless steel.
Mechanical Property Improvements on Ion Implanted Diamond
Authors: Hartley N. E. W.
Published: March 2011

A series of simple mechanical tests on single crystal diamond, diamond styli and diamond finishing tools has shown that frictional force, surface cracking and strength behaviour under simulated wear conditions can be improved as the result of N and Bion implantation at room temperature. Scratch tests on a polished macroscopic diamond of (111) planar orientation submitted to a total dose of 9.1015 N ions/cm2 revealed that a slight reduction in friction force occurred during dry sliding over the implanted region. Nitrogen implanted diamond gramophone styli held against a slowly rotating polished TiC disc under light load were found to significantly outlast unimplanted or carbon implanted samples, which generally failed abruptly on contact. In a third series of experiments, diamond tipped finishing tools used for high speed machining operationson acrylic plastic were implanted with N, B, and C ions to similar doses, all below 1016 per cm2. Nitrogen and boron implantations were found to improve the cutting life and quality of cut by as much as a factor 5, whereas carbon ions were much less effective.
Pulsed Laser Treatment of Virgin, Self and Europium Implanted Nickel: Evidence of Defect Impurity Interaction
Authors: Battaglin G. , Carnera A. , Della Mea G. , Mazzoldi P. , Jain Animesh K. , Kulkarni V.N. , Sood D.K.
Published: March 2011

We present a comparative study (by 1.8 MeV 4He+ ion channeling) of virgin, self and Eu implanted single crystals of nickel, under irradiation with single ruby laser pulses. The as implanted Eu is nearly non-substitutional and remains so, even after laser treatment. The comparative defect dechanneling behaviour provides explicit evidence of defect-impurity interaction which may be suppressing the formation of an expected metastable solid solution in the Eu-Ni system, which possesses miscibility in the liquid phase. A clear surface Eu peak appears at 2.1 J/cm2.
Dynamical Behavior of the Subsurface Region in Alloys Under Ion Bombardment at High Temperatures
Authors: Lam N. Q. , Wiedersich H.
Published: March 2011

Modifications of subsurface alloy composition by bombardment with ions of several keV energy were investigated theoretically, using a phenomenological model which includes the effects of various processes, such as preferential sputtering, displacement mixing, Gibbsian adsorption, radiation-enhanced diffusion, and radiationinduced segregation. The nonuniformity of damage rates, resulting from slow-down of the incoming ions, was also taken into account. The alloy composition evolution in time and space was calculated numerically for different temperatures, using concentrated Ni-Cu as a model alloy system. A good qualitative agreement between the present model calculations and recent experimental measurements was obtained.
Mechanical Properties of Ion-Implanted Thin Films and Interfaces
Authors: Miller G. L. , Soni M. , McDonald M. , Kaufmann E. N. , Fenstermacher R. L.
Published: March 2011

One of the areas of interest in the ion-beam modification of materials is that of alteration of specifically mechanical properties. To this end a method has been developed allowing in situ investigation of the stress, Young's modulus and mechanical hysteresis of small samples during and following ion-implantation. The samples are typically in the form of ~ 2 mm ⨉ 2 mm squares a few thousand angstroms thick, deposited on a ~ 50µ thick metal support, and forming a mechanical marginal oscillator. The measurement is carried out by flexing the samples at ~ 500 Hz under a servo-stabilized sinusoidal strain with a peak value in the range 0 to ~ 10−3. The accuracy of the method is typically ~ 1% or better for the measured quantities.

Results are presented showing strain dependent (nonlinear) mechanical effects, thermal annealing effects, ion implantation of boron into copper and ion-beam mixing of copper films on aluminum substrates.
Ultra-Microhardness Tests on Ion Implanted Metal Surfaces
Authors: Pethica J.B. , Oliver W.C.
Published: March 2011

To measure the mechanical properties of ion implanted layers special microhardness tests with penetration depths less than 100 nm have been made. The results show that increases in hardness of up to 50 % may occur in a number of metals as a result of nitrogen ion implantation. Considerable carbon is also present in the implanted surfaces and when in the form of a distinct layer, may give an apparent softening of surfaces at high doses.
Sem and Aes Analysis of Ion Implanted Graphite
Authors: Shayegan M. , Elman B.S. , Mazurek H. , Dresselhaus M.S. , Dresselhaus G.
Published: March 2011

Ion-implantation of graphite is characterized with respect to lattice damage and the distribution of implanted ions. Both the depth profile of the implanted ions and of the lattice damage are shown to follow the models previously developed for ion-implanted semiconductors. Auger electron spectroscopy (AES) is used to monitor the implantation profile. The surface damage is examined by scanning electron microscopy (SEM) while microcrystalline regions in an amorphous background are observed by scanning transmission electron microscopy (STEM).
Ion Beam Mixing of Sb Layers in Al
Authors: Paine Bruce M. , Nicolet Marc-A. , Banwell Thomas C.
Published: March 2011

We have studied the atomic mixing of Sb layers in Al induced by irradiation with 110 keV Ar ions. Samples with 10 and 230 Å Sb layers sandwiched in Al were made by sequential vacuum deposition and analyzed by backscattering spectrometry. The mixing was characterized by finding the increase, σ2, in the variance of the Sb signal in the backscattering spectra. For 10 Å layers irradiated at 90 and 270 K, the profiles are Gaussian and σ2 increases linearly with dose of implanted Ar ions. The mixing is essentially independent of temperature up to ∼ 290 K, where it increases sharply. For 230 Å layers irradiated at 90 and 270 K, the profiles are approximately Gaussian but develop a flat top as the Al:Sb ratio approaches 1:1. At 90 K σ2 increases monotonically with dose up to 3.6 × 1016 Ar/cm2, but at 270 K it develops a plateau at a dose of ∼ 2.2 × 1016 Ar/cm2, which corresponds to Al:Sb = 1:1. No such plateau is observed at 90 K. Again, the mixing showed very little variation with temperature between 90 and 270 K, but rose abruptly above 300 K.
The Meyer-Neldel Relation and Analysis of the Field-Effect In Amorphous Silicon
Authors: Schropp Ruud E. I. , Snijder Jan , Verwey Jan F.
Published: March 2011

The dependence of the conductance prefactor on the activation energy in accordance with the Meyer-Neldel relation has been observed in a-Si:H, by measuring the temperature dependence of the field-effect in a-Si:H thin-film transistors. The Meyer-Neldel rule is for the first time properly taken into account in the analysis of the field-effect, thereby considering the non-uniform shift of the Fermi-level as induced by the gate bias. The analysis also yields the flat-band voltage, which is an important parameter in the density of states evaluation. The density of states is shown to be considerably overestimated in conventional analysis.
Fluorine Incorporation and Annealing Properties of a-Si, Ge:H, F Alloys Studied by Elastic Proton Scattering and Ir Absorption
Authors: Schwarz R. , Okada Y. , Chou S. F. , Kolodzey J. , Slobodin D. , Wagner S.
Published: March 2011

We report precise measurements of the fluorine content cF in amorphous silicongermanium alloy films (a-Si, Ge:H, F). The films were prepared by r.f. or d.c. glow discharge deposition. The fluorine concentration was measured by elastic scattering (NES) of 12 MeV protons and by IR absorption spectroscopy. Films measured by NES serve as calibration standards for other measurement techniques. Using the NES measurements, we update the published calibration coefficient for IR measurements for cF ranging from 0 to 10 at.%. The annealing properties up to 700°C of a-Si, Ge:H, F were studied by the gas evolution technique and by IR spectroscopy. Above 300°C the Si-F absorption peak decreases while the peak due to SiF4 molecules increases. No significant loss of F from the alloy films seems to occur up to 700°C.
Internal Photoemission Measurements for the Determination of Schottky Barrier Height on a-Si, Ge:H, F Alloys
Authors: Chu V. , Aljishi S. , Slobodin D. , Wagner S.
Published: March 2011

We report measurements of internal photoemission from Ni, Au, and Pd contacts into a-Si, Ge:H, F alloys. The alloys were prepared by d.c. glow discharge decomposition of either SiF4 or SiH4 and GeF4, and H2. The sharp exponential drop in subgap absorption in these alloys, measured by the Constant Photocurrent Method (CPM), allows the determination of barrier heights using internal photoemission thresholds. The barrier heights of Ni, Au and Pd contacts are presented as a function of alloy composition. We find Ni has the lowest barrier heights while Au shows the highest barrier heights over the entire range of Eopt. We also find that for the Ni and Au contacts, ΦB varies as 1/2 the optical gap. In the case of Pd, ΦB shows a dependence of 1/3 the optical gap. We observed an increase in ΦB for Pd contacts when etched with a diluted HF solution prior to metallization. A similar increase in ΦD was not observed for the Au and Ni contacts.
Hydrogenated Amorphous Silicon Thin-Film Deposition by Direct Photo-Enhanced Decomposition of Silane Using an Internal Hydrogen Discharge Lamp.
Authors: Robertson P. A. , Milne W. I.
Published: March 2011

Hydrogenated amorphous silicon (a-Si:H) thin films have been deposited from silane using a novel photo-enhanced decomposition technique. The system comprises a hydrogen discharge lamp contained within the reaction vessel; this unified approach allows high energy photon excitation of the silane molecules without absorption by window materials or the need for mercury sensitisation. The film growth rates (exceeding 4 Å/s) and material properties obtained are comparable to those of films produced by plasma-enhanced CVD techniques. The reduction of energetic charged particles in the film growth region should enable the fabrication of cleaner semiconductor/insulator interfaces in thin-film transistors.
Properties and Local Structure of Plasma-Deposited Amorphous Silicon-Carbon Alloys
Authors: Mohr W. C. , Tsai C. C. , Street R. A.
Published: March 2011

Hydrogenated amorphous silicon-carbon alloy films were plasma-deposited from metnane and silane, varying gas ratio, R.F. power and substrate temperature. Carbon addition increases the optical gap, but also raises the dangling bond density while decreasing conductivity. Low C alloys can be gas-phase doped both p and n type. In the IR spectra the various Si-C stretching modes observed between 650 and 780 cm-1 are explained by back bonding variations. A tentative method of assigning this shift to back bonding of C to the Si is given. A distribution of modes is observed for all alloys, with each mode appearing even at 2% C. The distribution is sensitive to substrate temperature, but is stable after vacuum annealing to 400°C.
In Situ Studies of the Microstructure of a Si:H Surfaces and Interfaces
Authors: Collins R. W.
Published: March 2011

Using in situ ellipsometry with a 3.4 eV probe, we have characterized the initial nucleation and interface structure of a-Si:H and μc-Si deposited on oxide/c-Si substrates. Multilayered a-Si:H/a-SiNx:H structures have also been studied and non-uniformities have been modeled. In none of the reported data could we model thin film growth with thickness independent optical functions. Once a film becomes opaque, ellipsometry is very sensitive to changes in the thickness of surface roughness layers. As a result, roughness on single and multilayered a-Si:H films has been studied as well as the renucleation that results from stopping and then restarting the a-Si:H growth plasma.
Hydrogenated Amorphous Silicon Alloys Prepared by CVD of Higher Silanes
Authors: Akhtar Masud , Weaklie Herbert A.
Published: March 2011

Hydrogenated amorphous silicon may be deposited at relatively low temperatures, where the density of defects may be expected to be low, by the chemical vapor deposition (CVD) of higher silanes. This method is an attractive alternative to plasma deposition techniques. We describe here the preparation of a-Si:H and related alloys incorporating carbon, germanium, and fluorine. a-Si:H films were deposited on heated substrates in the range 365°C-445°C by CVD of Si2H6 and Si3H8. The optical gap (Eg) ranged from 1.4 to 1.7 eV and the properties of films deposited from either Si2 H6 or Si3 H8 were quite similar. Wide band gap (Eg=2 eV) alloys of a-SiC:H doped with boron were prepared by CVD of disilane, methyl silane, and diborane. We also prepared variable band gap a-SiC:H alloys by substituting F2C= CFH for methylsilane, and these films were found to have approximately 1–2% fluorine incorporated. The dark conductivity of the boron doped a-SiC:H alloys dep~sited from either carbon source ranged from ix10-7 to 6x10-7 (ohm-cm)-1. We also prepared low band aap alloys of Si and Ge by CVD of trisilane and germane. The band gap of a film containing 20% Ge was 1.5 eV; however, the photoconductivity of the film was relatively low.
Recent Advances in A-Si Solar Cell Technology in Japan
Authors: Kuwano Y.
Published: March 2011

Recent advances in a-Si solar cells in Japan are reviewed. Improvements in single-junction and multi-junction solar cells are described in three main points, namely, fabrication methods, materials, and cell structures. Recently, a conversion efficiency of 11.7% was obtained for a single-junction structure. For an a-Si/poly-Si stacked structure and an a-Si/(CdS/CdTe) 4 terminal structure, conversion efficiencies of more than 13% were achieved.

Then recent advances in the prevention of the light induced degradation of a-Si solar cells is mentioned. Several methods which can improve the a-Si solar cell stability are described.

Finally, the present status of the industrialization of a-Si solar cells and some of the latest applications are described together with their propects.
Status of Fluorinated Amorphous Silicon Alloy Multi-Junction Solar Cells
Authors: Yang Jeffrey , Ross Robert , Mohr Ralph , Fournier Jeffrey P.
Published: March 2011

We present in this paper updated solar cell performance data on fluorinated amorphous silicon and fluorinated amorphous silicon-germanium alloys. We have achieved a 9.7% conversion efficiency for a singlejunction device using a-Si:Ge:F:H alloy having an optical band gap of 1.5 eV. We have also achieved 12.5% and 13.0% efficiencies, respectively, for dual-band-gap tandem and triple devices using a-Si:F:H and a-Si:Ge:F:H alloys. These represent the highest values reported to date for their respective configurations. Multi-junction solar cells exhibit excellent stability not only in terms of light-induced effect but also in terms of prolonged heating at elevated temperatures.
Effect of Superlattice Doped Layers on the Performance of a-Si:H P-I-N Solar Cells
Authors: Arya Rajeewa R. , Catalano Anthony , O'dowd James
Published: March 2011

Superlattice doped layers of the type ABABAB … have been prepared where A is the wide bandgap a-Si:C:H doped layer and B is the narrow bandgap a-Si:C:H or a-Si:H doped layer. The bandgaps of the individual layers were modulated by changing the gas phase composition of methane during the plasma deposition. By varying the structure of the films, superlattice p-layers with resistivities in the range of 106 - 107 ohm-cm with optical bandgaps of 2.0 - 2.4 eV, and activation energies of 0.35 - 0.48 eV and superlattice n-layers with resistivities in the range of 104 - 105 ohm-cm with optical bandgaps of 1.86 - 2.03 eV and activation energies of 0.38 - 0.47 eV have been obtained.

P-I-N solar cells have been prepared with both p and n layers comprised of superlattice structures. Conversion efficiencies as high as 10.86% have been achieved under simulated AM1.5 Global conditions. Measurements reveal a marked improvement in both built-in voltage and carrier collection length.
The Effects of Dopant Profiles on the Device Parapmetrs of p-i-n and n-i-p a-Si Solar Cells
Authors: Jeffrey F. R. , Vernstrom G. D. , Weber M. , Epstein K. A.
Published: March 2011

we have studied the effects of intrinsic layer dopant profiles on the open circuit voltage and fill factor of p-i-n and n-i-p solar cells. Data is presented showing that boron profiling into the i-layer is responsible for the commonly observed difference in open circuit voltage between p-i-n and n-i-p devices. As only a shallow profile is required to produce this effect, it is proposed that the lower Voc samples are being limited by surface recombination at the p/i interface and that the boron profile reduces this recombination current. The fill factor for devices illuminated through the n+ layer is shown to be very sensitive to the depth of a boron profile, yet not so sensitive to the profile concentration. A maximum occurs for a profile penetrating slightly more than half way through the cell. Spectral response data clearly shows a shifting of high collection from the back to the front of the cell.
Transient Behavior of Phoioxcurrent in a-Si :H Solar Cells
Authors: Cuang Gad , Qing Miao , Baocheng Cao , Xiaoqin Guo , Guocai Dai
Published: March 2011

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Time-dependent photocurrent response by the monochromatic square-pulsed excitation light of different wavelenths has been studied on the PIN a-Si:H solar cells. The experiments show that the shape of the photocurrent transient is distinctly changed by varying the photon energy of the excitation light and the applied biases. Our results can be explained by the relaxation of space charge distribution in the i-layer.
Light-Induced Effects in a-Si:H Films and Solar Cells
Authors: Uchida Yoshiyuki , Sakai Hiroshi
Published: March 2011

The present state of a-Si:H solar cells and studies on the light-induced effects in a-Si:H films and a-Si:H solar cells are presented. The conversion efficiencies attained are 11.5%, 10.1% and 7.5% (8.5% in active area) for 1.0cm2 singlejunction, multijunction cells and 1200cm2 submodule, respectively. The density of light-induced defects, ANs, changes with deposition temperature and annealing temperature. This suggests a strong correlation between the ANs and the network structure in a-Si:H films. Field testing results indicate that the degradation of a-Si:H modules can be suppressed within 10% of the original efficiency after 2 years operation. It is also indicated that the multijunction cells are more stable to light exposure than single p-i-n cells.
Stability of Amorphous Silicon Solar Cells — New Tandem a-SiC/a-Si Solar Cell
Authors: Tawada Y. , Takada J. , Yamaguchi M. , Yamagishi H. , Hosokawa Y. , Hiroe A. , Kondo M. , Asaoka K. , Fukada N. , Tsuge K.
Published: March 2011

Basic technologies for solving problems in thermal and light-induced degradation have been developed. The tandem type a-SiC/a-Si solar cell with blocking layers exhibits excellent stability for both thermal and sun light conditions. An observable light-induced degradation is not seen in the cell performance after light exposure test of 2000 hours. Two instability modes, that is, thermal and light-induced degradation have been investigated. For thermal degradation, a blocking layer for preventing diffusion has been inserted between the back side metal electrode and a n-layer and another blocking layer has been introduced between the np tunnel junction. To prevent light-induced degradation, p-type a-SiC layer of the pin structure on the side of a glass substrate/SnO2 has been deposited at the temperature of 70°C. The highest efficiency is 9.0% at the present stage, but it is expected to be improved to more than 10%.
The Materials Issues and Applications of Amorphous Silicon Thin Film Transistors
Authors: Thompson M. J.
Published: March 2011

Recently considerable interest has been generated in the application of thin film transistor (TFT) technology in electronic input and output devices. Amorphous silicon (a-Si:H) has made a major impact in these applications because of the relative ease with which the material can be economically manufactured over large areas. This paper will review in particular the current status of a-Si:H TFTs in liquid crystal display and printer applications, in addition to sensor/TFT arrays for page width input scanner document readers. There are a number of materials issues which limit the performance of these devices. In addition, there are some technological issues which influence the yield of the processes used to fabricate these electronic devices over large areas. Some novel new devices have been recently developed which dramatically increase the operating voltage of a- Si:H TFTs. Other new structures have been proposed and demonstrated for increasing the current and speed of these devices.
Electrophotographic Properties of n+-a-Si:H/a-Si:H/a-Sic:H Heterostructures
Authors: Paasche S. M. , Bauer G. H.
Published: March 2011

For negative charging electrophotographic applications a three layer heterostructure (Al/n+-a-Si:H/a-Si:H/a-SiC:H) has been investigated. To some extent a separation of the function of charge storage by a high band gap amorphous silicon carbon alloy and of that of photogeneration of carriers and of sufficient photosensitivity in an intrinsic amorphous silicon film has been achieved. Due to a low injection of electrons from the surface into the a-SiC:H and a small thermal generation rate of carriers within the a- Si:H film, the dark decay of the negative surface potential is dominated by space charge limited currents of holes. Thus a considerable difference in surface potential for negative and positive charging occurs, which is related to the difference in electron and hole mobility in a-Si:H. Since there is no remarkable barrier at the heterointerface a-Si:H/a-SiC:H an excellent injection of photogenerated holes into the a-SiC:H can be provided.
A-SI:H Image Sensors: Some Aspects of Physics and Performance
Authors: Rosan K. , Brunst G.
Published: March 2011

High photosensitivity and fast photoresponse have proved a-Si:H to be a suitable thin-film photoconductor for large-size linear image sensors. Besides the a-Si:H bulk properties, the a-Si:H/electrode interfaces are of major influence on the sensor performance. In view of this performance, the readout circuit has to be designed carefully with respect to the desired dynamic range. Care has to be taken to avoid electrostatic hazards when mounting the sensor, as the breakdown voltage of a-Si:H sensor elements was found to be about 60 volts.
Influence of Unsymmetrical Electrode structure on a-Si Photodiode Characteristics
Authors: Hayama M. , Kobayashi K. , Miki H. , Onishi Y.
Published: March 2011

Amorphous silicon(a-Si) stripe p-i junction photodiode array for contact-type image sensor of a facsimile has been developed and investigated especially with regard to its unsymmetrical electrode structure. This sensor consists of a p-i a-Si stripe layer, Cr separate electrodes, and an ITO common electrode. As a result, it is found that the photosensitive region of a-Si stripe type photodiode exists not only in a-Si sub-region having both upper and lower electrodes but also in a-Si sub-regions having upper or lower one-sided electrode. It is considered that photocarrier collecting mechanisms in the a-Si sub-regions are different and result to the different photodiode characteristics.
Multiple Quantum NMR Study of Hydrogen Clustering in Amorphous Silicon
Authors: Gleason Karen K. , Baum J. , Garroway A. N. , Pines A. , Reimer J. A.
Published: March 2011

Because Multiple Quantum NMR coherences occur only between spins which are coupled together by the dipole interaction, this technique has been used to study the clustering of hydrogen in amorphous silicon. The clustered hydrogen was found to be associated with the broad line of the single quantum NMR spectra. For device quality films, the average cluster size is approximately six protons. The concentration of these five to seven atom defects increases with increasing hydrogen content until, at very high hydrogen content, the clusters are replaced by a continuous network of silicon-hydrogen bonds.
Annealing Effects on Deuterium in a-Si:D.
Authors: Bork V. P. , Fedders P. A. , Leopold D. J. , Norberg R. E. , Boycea J. B. , Knights J. C.
Published: March 2011

Progressive annealing of a-Si:D and a-Si:DH samples between 250 and 600°C is found to eliminate the broad central deuteron magnetic resonance (DMR) spectral component associated with weakly bonded D. The well-resolved doublet arising from tightly bound D diminishes in intensity. The narrow central line associated with microvoid-contained molecular D2 and HD increases and then decreases for the warmest anneals. DMR relaxation times, line shapes, and hole-burning spectra reflect changes in sample morphology upon annealing.
Growth of GeSi/Si Strained-layer Superlattices Using Limited Reaction Processing
Authors: Gronet C. M. , King C. A. , Gibbons J. F.
Published: March 2011

SiGe/Si superlattices were grown using limited reaction processing in a chamber which allows both W-halogen and Hg arc wafer illumination. Each multilayer structure was fabricated in-situ by changing the gas composition between high temperature cycles. Commensurate SiGe alloy layers as thin as 15 nm were reproducibly deposited and were examined using transmission electron microscopy, sputtering Auger electron spectroscopy,and Rutherford backscattering. Preliminary results are presented on UV/ozone cleaning of LRP substrates to remove residual carbon contamination in-situ prior to film deposition.
Epitaxial Growth of Silicon Using Photochemical Vapor Deposition at a Very Low Temperature of 200º Centigrade
Authors: Konagai M. , Nishida S. , Yamada A. , Shiimoto T. , Karasawa S. , Takahashi K.
Published: March 2011

A new technique for silicon epitaxial growth has been developed using mercury—sensitized photochemical vapor deposition (photo—CVD). Epitaxial thin layers were grown on (100) Si substrates at 100–300ºC from a gas mixture of Si2H6+AiH2F2+H2 by irradiation of a low pressure mercury lamp (1849A, 2537A). Refiective high energy electron diffraction (RHEED) and Raman scattering measurements showed that the epitaxial layers had good crystallinities.The epitaxial layers were characterized by secondary ion mass spectroscopy (SIMS) and the van der Pauw Hall2 measurements. The undoped Si layer showed the electron mobility of 520cm2/Vs with a carrier concentration of 3.2xl04cm
Slant-Scanning and Interstice-Bridging Applied to ZMR to Improve the Quality of Recrystallized Si Films on Quartz
Authors: Tomita Hisashi , Kojima Shigeru , Usui Setsuo
Published: March 2011

CMOS test circuit chips have been fabricated for the purpose of evaluating Si film recrystallized on quartz wafers by using a graphite-strip heater oven equipped with a micro-computer feedback system. Two new methods have been applied to the zone-melting recrystallization technique to produce a highly uniform and grain boundary (GB) free recrystallized Si film. The slant-scanning method was used to control the GB's location in recrystallized Si film of 180μm wide stripes separated by 20μm. The intersticebridging method was used to reduce the (111) texture generation to less than 1%. The average electron mobility and the average threshold voltage for MOSFET's were 960cm2/V sec, with a standard deviation of 43cm2/V sec, and 1.38V with a standard deviation of 0.25V, respectively. For the ring oscillator, at a supply voltage of 12V, the propagation delay time was 1.7nsec per stage. The maximum response frequency was higher than IMHz for the CMOS inverters.
Submicron Highly Doped Silicon Epitaxial Layers Grown by Lpvpe
Authors: Vescan L. , Beneking H. , Meyer O.
Published: March 2011

By low pressure vapour phase epitaxy (LPVPE) epitaxial growth down to 760ºC has been achieved in the SiC12H2/H2 system, as revealed by RBS and channeling measurements ( min ∼4.0%). High and relative homogeneous doping was obtained with boron resp. phosphorus in the range 1x1018 -5x1019 cm-3 for T: 800º - 900ºC. Sharp transitions in the boron doping profile to the substrate, of the order of 15mn, result only for temperatures much lower than 850ºC. Schottky barrier enhanced diodes with promising performances were formed with Ti evaporated on p+n layers grown selectively on n+ substrates.
Defect Reactions and Atomic Diffusion in Silicon
Authors: Pantelides Sokrates T.
Published: March 2011

Atomic diffusion is generally mediated by intrinsic defects such as vacancies and self-interstitials. In this paper we give a critical review of the relevant properties of intrinsic defects in Si as they have been determined by experiments and recent theoretical calculations. We then review the role of these defects in mediating self-diffusion and dopant impurity diffusion both under equilibrium and non-equilibrium conditions. A systematic and internally consistent picture emerges, but many processes, such as oxidation-modified and nitridation-modified diffusion require more systematic data for detailed understanding.
Electrical Characteristics of Silicon p+n Diodes Fabricated BY B+ Implantation and Rapid Thermal Annealing in the Temperature Range 700 - 1000°C
Authors: Usami Akira , Katayama Masayuki , Tokuda Yutaka , Wada Takao
Published: March 2011

B+ implanted p+n diodes were fabricated by rapid thermal annealing (RTA) in the temperature range 700 - 1100°C. Values of series resistance of diodes decreased with the annealing temperatures. Leakage current (Ir) was independent of the RTA temperatures. Residual defect concentrations increased in the range 700 - 900°C and decreased in the range 1000 - 1100°C. Concentrations of defects with the energy levels of Ec- 0.33 and Ec - 0.48 eV were ∼ 1012 cm−3 for diodes fabricated at 1100°C. The growth of defects in the range 700 - 900°C was ascribed to the diffusion of defects from the implanted layer during annealing.
Low Pressure Chemical Vapor Deposition of Tungsten and Aluminum for VLSI Applications
Authors: Levy R. A. , Green M. L.
Published: March 2011

This paper reviews the current status of LPCVD tungsten and aluminum for VLSI applications. Using deposition chemistries based on tungsten hexafluoride and tri-isobutyl aluminum, W and Al deposits are characterized with respect to their electrical, mechanical, structural, chemical and optical properties. Although results of this study prove these two LPCVD processes to be compatible with current VLSI fabrication, certain problems must still be resolved for complete commercial acceptance. These problems include, in the case of selective LPCVD tungsten, the occurrence of leakage current across N+/P-Tub junctions, and in the case of LPCVD aluminum, the relatively poor electromigration resistance (compared to Al-Cu) and excess surface roughness.
Characteristics of Electromigration in Aluminum Interconnect Lines for Integrated Circuits
Authors: Schreiber H.-U.
Published: March 2011

Reliability of Al metallization is strongly influenced by electromigration. In Al lines there are at least two competing failure modes. On the one hand, mass flow divergencies can produce stripe interruptions, and on the other hand, homogeneous mass flow, which is described by the Al drift velocity, can lead to contact openings. Test results indicate that the drift velocity limits the lifetime of metallization. Worst case failure behavior should be measured in long test lines, since there is an electromigration threshold, which affects mass flow in shorter lines. Al reliability can be improved by reducing the total mass flow.

This might be done by influencing electromigration mechanisms. Considering electromigration threshold, grain boundary and interface electromigration can be eliminated in large-grained, narrow lines. The extremely low mass flow of the remaining mechanism is beneficial for the reliability of metallization.
Gettering In Silicon
Authors: Seidel T. F.
Published: March 2011

This paper reviews the basis for phenomenological path for gettering: release, diffusionand capture in the context of old and new developments. More recent precipitation studies in silicon are now recognized to involve complex interactive effects. Controlled precipitation requires knowledge of and control of not only oxygen but carbon, native defects(related to crystal thermal history and/or process history), high doping, microfluctuations and interactions between “extrinsic” and “intrinsic” gettering.
Mo/Cr Metallization for Silicon Device Interconnection
Authors: Kim M. J. , Saia R. A.
Published: March 2011

A molybdenum and chromium double layer contact has been developed for the first level metallization of VLSI circuits. An 800Å layer of chromium deposited under a thick molybdenum conductor provides good ohmic contact to p+ and n+ silicon and also promotes metal adhesion to the substrate. The molybdenum has good step coverage and acceptable current carrying capacity when its thickness exceeds 5000Å. Both metals are sequentially sputtered in one pumpdown and patterned with a single RIE step using CCI4 + O2. One pm diameter contacts and 1.5µm wide lines are formed in VLSI geometries using all dry etch processes. Electrical characteristics and thermal reliability were evaluated as a function of annealing temperature. Contact resistance and shallow device junctions are stable up to 500°C for p+/n diodes and up to 450°C for n+/p diodes. The sheet resistance of the film in contact with silicon rapidly increases at 525°C as silicon outdiffuses to form (Mox Crr−x)Si2 The mechanism and cause of the high temperature degradation was studied by mean of SIMS, x-ray diffraction analysis, SEM and electrical measurements.
Infrared Absorption Study of Porous Silicon
Authors: Harwood P.B. , Thomes G.P.
Published: March 2011

Data is presented which links the 620 - 660 cm−1 infrared absorption doublet in porous silicon films to the presence of silicon hydride. This band assignment explains both the magnitude and thermal behavior of the doublet, and is in agreement with published data on silicon hydrides.
The Properties Of Phosphorus In Polycrystalline Silicon - A Nuclear Magnetic Resonance Study
Authors: Mccarthy Michael J. , Meyerson B. , Karim M. S. , Reimer J. A.
Published: March 2011

Phosphorus segregation at grain boundaries in thin film polycrystalline silicon has been investigated by nuclear magnetic resonance spectroscopy. Amorphous silicon thin frims were deposited by plasma enhanced chemical vapor deposition with 1% phosphine in silane. The films were subsequently annealed at 700°C and 800°C to produce a fine grained polycrystalline material. All of the phosphorus atoms were found to be four-fold coordinated at the grain boundary. The P atoms were found to have three different environments in the grain boundary region. These results will be discussed in relationship to the carrier trapping and dopant segregation models.
A Novel Silicided Shallow Junction Technology for Cmos VLSI
Authors: Kwong D.L. , Ku Y.H. , Lee S.K. , Alvi N.S. , Chu P. , Zhou Y. , White J.M.
Published: March 2011

A novel technique for the fabrication of shallow, silicided p+-n junctions with excellent electrical characteristics has been developed. The technique utilizes the ion implantation of dopants into silicide layers formed by ion-beam mixing with Si ions and low temperature annealing, and the subsequent drive-in of implanted dopants into the Si substrates to form shallow junctions. This technique can be easily applied to the fabrication of MOSFETs in a self-aligned fashion, and can have a significant impact on CMOS VLSI technology.
Shallow Silicided Junctions for VLSI Cmos Transistors by Furnace and Rapid Thermal Processing
Authors: Butler A.L. , Foster D.J. , Pickering A.J.
Published: March 2011

As a result of device scaling very shallow low resistance diffusions are required for VLSI CMOS fabrication. This paper describes a technique for their formation using silicon implantation for preamorphisation, counterdoping arsenic implantation and overall boron fluoride implantation for the sources and drains of the n- and p-channel transistors. Platinum silicidation has been used to reduce diffusion and polysilicon sheet resistances to 8Q/square. Activation of the shallow diffusions has been achieved either by furnace annealing (FA) or rapid thermal annealing (RTA) in the range 900°C to 1100 °C. Materials results are discussed including TTEM, SIMS and SR profiling. The suitability of the technique for VLSI CMOS applications is demonstrated by the fabrication of sub-micron transistors. With larger wafer diameters (>5') the FA conditions considered are not practicable owing to ramped diffusion effects which lead to deeper junctions. Hence RTA is necessary: optimum conditions found were 1100 °C for 10 seconds when device performance equivalent to or better than FA can be achieved.
Development Trends in The Direction of Rapid Isothermal Processing (Rip) Dominated Silicon Integrated Circuit Fabrication
Authors: Singh R. , Nulman J.
Published: March 2011

This paper summarizes the development in the direction of rapid isothermal processing (RIP) dominated silicon integrated circuit fabrication technology.
Applications of High-Pressure Technology to Ulsi Fabrication
Authors: Tay S.P. , Ellul J.P. , King M.I.H.
Published: March 2011

A discourse is presented on the diverse manners and extent to which high-pressure reactors are being utilized in the semiconductor industry and their potential employment in research and development for ULSI fabrication. Various versions of high-pressure reactors are described. The major advantages of high-pressure techniques stem mainly from the ability to use lower processing temperatures which leads to reduced impurity diffusion, less wafer warpaqe, and fewer substrate defects. The exploitation of these benefits in LOCOS and FIPOS technologies for silicon IC device isolation is demonstrated. High-pressure steam has also been used to induce low-temperature reflow of PSG and BPSG before metallization. The applications and limitations of this technology are critically reviewed. Other application areas of high-pressure technigues being investigated extensively by R&D workers are discussed. These include the formation of reliable thin dielectrics in high-pressure ambients of oxygen, steam, nitrogen and ammonia, as well as the improvement of device reliability by using high pressure forming gas (H2/N2) in post-metallization annealing of radiation damage. Enhanced capabilities required for a conventional high-pressure reactor to achieve these applications are discussed. The review is complemented with data which reveal a rapidly growing utilization of high-pressure reactors for production as well as a steady growth in the number of potential applications for high-pressure techniques.
Growth and Characterization of Epitaxial Insulating CaF2ON Si
Authors: Phillips Julia M.
Published: March 2011

The growth of epitaxial insulators on semiconductors in general and on Si in particular is an area of research which has developed quickly over the last five years. Most of thecurrent interest is in films of materials which can be grown by molecular beam epitaxy. A significant fraction of all of the work in this area has concerned the CaF2/Si system. This review will cover that body of work.
Precipitation of PZT and PLZT Powders Using a Continuous Reactor
Authors: Schwartz R. W. , Eichorst D. J. , Payne D. A.
Published: March 2011

PZT and PLZT powders were prepared from nitrate and chloride precursors in a continuous constant volume precipitator. After precipitation, the powders were dried by a variety of methods, including: spray-drying, freeze-drying (in liquid nitrogen), and centrifugal freeze-drying. Spraydried powders were found to have a spherical morphology, and to be solid. The particle size was in the micron range. Powders dried by nitrogen freezedrying were characterized by an open morphology of agglomerated platelets. For centrifugally freeze-dried powders, particle size analyses were found to fit a population balance model, giving crystallite, cluster, and agglomerate population densities and growth rates.
Kinetic Investigations of Alkoxysilane Sol-Gel Processing
Authors: Hardman-Rhyne K. A. , Coyle T. D. , Lewis E. P. , Spooner S.
Published: March 2011

Effective control of sol-gel glass processing requires a detailed understanding of the kinetic and mechanistic aspects of the process. We have investigated structural evolution at the molecular level in the tetramethoxysilane (TMOS) hydrolysis reaction by various spectroscopic techniques. Development of structure at the macromolecular level and evolution of particle/network dimensionality have been studied by small-angle x-ray scattering (SAXS) in both hydrogenated and fully deuterated reactions for silica macromolecular structural development.
Movement of a Drying Front in a Porous Material
Authors: Shaw T. M.
Published: March 2011

A technique is described for directly observing the movement of a drying front through a thin layer of porous material. The observations show that the front moves in abrupt steps and develops an irregular morphology as it advances. Comparison of the experimental images with computer simulations indicates that several features of the drying front can be accounted for by a model based on invasion percolation.
Viscoelastic Probes of Suspension Structure
Authors: Zukoski C. F. , Goodwin J. W. , Hughes R. W. , Partridge S. J.
Published: March 2011

The use of the high frequency elastic modulus, G∞, to probe particle interactions in weakly agglomerated, concentrated suspensions is discussed. We show that a model based on pair interaction potentials and a statistical description of pair spatial distribution yields accurate prediction of the volume fraction dependence of G∞. The use of statistical treatments of particle distributions as predicted from particle interaction potentials is found to provide insight on how surface chemistry affects the uniformity of powder compacts.
Saxs Study of Silica Sols and Gels
Authors: Orcel Gerard , Gould Robert W. , Hench Larry L.
Published: March 2011

Small angle X-ray scattering was used to characterize the structure of sols and gels in the TMOS-MeOH-H2O-CHONH2 system. The scattering curves were analyzed in both the Porod and Guinier regions. A fractal analysis shows that the structure evolves with time and temperature from a linear type polymer to a more highly branched polymer and then towards a “particle”. However, these structural units disappear when the temperature increases above a critical value.
Growth and Structure of Fractally Rough Silica Colloids
Authors: Keefer K. D.
Published: March 2011

Small-angle x-ray scattering measurements on partially hydrolyzed silicon tetraethoxide solutions indicate the formation of colloidal particles which have fractal structures or fractally rough surfaces. The structures and growth kinetics are consistent with chemically limited nucleation and growth of the particles from slowly generated reactive silanol species. Two dimensional computer simulations of nucleation and random growth of clusters from partially hydrolyzed monomers generate the same range of non-fractal, fractally rough and fractal clusters observed in the experiment.
Fractal Aspects of Surface Science - An Interim Report
Authors: Avnir David
Published: March 2011

The activity in our laboratory and in collaboration with other laboratories in applying fractal geometry for the characterization of irregular surfaces and materials and for the analysis of molecular interactions with such objects are summarized in this report. Most of the studies were performed on the xerogel of silica. Various theories and experimental techniques have been employed for this purpose. They include adsorption studies, computerized image analyses in one (boundary lines), two (textures) and three (proteins) dimensions; non-radiative, Förster-type, one step electronic energy transfer (EET); small angle X-ray scattering; and analysis of chemical reactivity of fractal objects. The relation between porosity and fractal dimension has been studied by EET, by the photophysics of adsorbed pyrene and by monolayer adsorption studies. A direct method for the determination of adsorption conformations has been developed. Limitations of the fractal approach have been identified and outlined.
Structural Observations of Porous Silica Gels
Authors: Shafer M. W. , Castano V. , Krakow W. , Figat R. A. , Ruben G. C.
Published: March 2011

Silica gels were prepared by two methods; from the alkoxides under conditions where moderate degrees of crosslinking are expected and from LUDOX - alkaline silicate sols from which the alkali was subsequently removed. By selective thermal treatment from 300 to 850°C, pore diameters (excluding micropores) in the range 35Å to 400Å are seen. The pore size increased with temperature while the surface area and total porosity remained essentially constant. Extensive high resolution TEM analyses showed both colloid and polymeric structures with particle sizes between 60Å and 250Å which decreased on heating. An intra particle structure, presumably micropores of 10Å to 30Å is also seen. By using a shadow cast Pt-C replica technique, stereoimages show the particles to have a filamentry type structure.
The Role of Chemical Additives in Sol-Gel Processing
Authors: Hench L. L. , Orcel G. , Nogues J. L.
Published: March 2011

The effect of various concentrations of formamide with and without acid catalysis on TMOS derived silica sol and gel structures and physical properties is described using a quantitative structural model. The model is based upon 29Si NMR, SAXS, Raman and FTIR spectroscopy, and an acid solubility test. Changes in chemical reactions during drying due to formamide are presented using FTIR, DSC and TGA data.
Applications of Molecular Dynamics Simulations to Sol-Gel Processing
Authors: Carofalini S. H. , Melman H.
Published: March 2011

The molecular dynamics computer simulation technique has been used to study silicic acid and pyrosilicic acid molecules (H4 SiO4 and H6 Si 2 O7, respectively). The structure of the simulated molecules are compared to those found by molecular orbital calculations as well as structures inferred from silicate hydrates. The potentials used to simulate the molecules were also used in simulations of bulk silicates and compared with experimental data. Results indicate good correlation.
Si-O-N Ceramics From Organosilicon Polymers
Authors: Yu Yuan-Fu , Mah Tai-Il
Published: March 2011

The preparation of new, hybrid pre-ceramic organosilicon polymers are described. These hybrid polymers were prepared by reactions of polysilazanes and polysiloxanes. Ceramic materials containing Si-O-N were obtained with high yields (∼ 80%) by pyrolyzing these new polymers at low temperatures (< 800°C). A wide range of chemical compositions and properties can be obtained by using different ratios of polysilazanes and polysiloxanes. Microstructural characterization and densification studies of these ceramic materials are presented.