bluuebunny/crossref_metadata_2025_split huggingface dataset:
In Situ Measurement of Stress. Included During Annealing, in A1-2%Cu Thin Films
Authors: Townsend P. H. , Plas H. A. Vander 
Published: March 2011

ABSTRACTStress measurement in thin film systems is discussed and applied to Al-2%Cu filns on SiO2/Si substrates during thermal cycling. Plastic deformation obscrved during compressive stress relaxation is correlated with the formation of hillocks on the metal films. The effect of secondary layers of 10%Ti-90%W on the thermo-mcchanical response of Al films is examined.
Metal-Germanium Contacts and Germanide Formation
Authors: Marshall E. D. , Wu C. S. , Pai C. S. , Scott D. M. , Lau S. S. 
Published: March 2011

ABSTRACTIn this study, we survey germanide formation and characterize Schottky- barrier properties for a number of representative metals on Ge (Al, Ag, Au, Er, Ni, Pd, Pt, Ta and Ti). It is found that the germanide formation characteristics (sequence of phase formation, kinetics, moving species) are similar to those of the corresponding silicides. The Schottky-barrier heights, however, are all similar and centered around 0.59 eV arida re relatively insensitive to the metallization.
Esca Studies of the Valence band and Loss Spectra of Semiconductor Films: Ionicity and Chemical Bonding
Authors: Barr T. L. , Kramer B. , Shah S. I. , Ray M. , Greene E. 
Published: March 2011

ABSTRACTESCA valence band and core level loss results have been determined that appear to be directly related to the degree of covalency/ionicity and other bonding features of certain semi-conductor systems. Specific applications are presented that aid in the characterization of the key chemistry of dielectric oxide/semiconductor interfaces and also may help to determine the relative metastability of the solid solution of Group IV elements (e.g., Ge) into certain III-V lattices (e.g., GaAs). It is shown that these features are not detectable through conventional core level shift arguments, and that the aforementioned novel approaches often require high resolution ESCA.
The Production of Doped Amorphous GaAs by Co-Sputtering With Mo
Authors: Najar S. , Sedeek K. , Lalande F. , Carchano H. 
Published: March 2011

ABSTRACTStoichiometric amorphous GaAs films with intrinsic properties have beer produced by R.F. Sputtering in pure argon at high substrate temperature of 290°C. The electronic and the optical properties of this material have been modified by the molybdenium co-sputtering. This paper reports: on several modified material parameters including the electrical conductivity, thermal activation energy and optical gap. Atomic Mo concentrations up to 1.24% have been investigated. It is observed that the room temperature conductivity can be controlled over about six orders of magnitude, which corresponds to a shift in the Fermi level of 0.45 eV towards the conduction band edge. For optical parameters, the optical gap has been reduced by 0.1 eV. An additional absorption tail due to localized states introduced by doping atoms is observed. It is concluded that our a-GaAs have the main requirement, i. e low density of defect gap states, for effective doping with analogy to a-Si prepared either by glow discharge or by sputtering in argon-hydrogen plasma.
Adhesion at Metal-Ceramic Interfaces: Ion Beam Enhancement and the Role of Contaminants
Authors: Baglin J. E. E. 
Published: March 2011

ABSTRACTEnhanced adhesion of a film of non-reactive metal deposited on a ceramic or glass substrate can be produced by irradiating the interface with an ion beam. The resulting bond can be improved by subsequent heat treatment. The interface remains abrupt. The mechanism of this bonding is discussed, and the effects of interface contaminants are examined for the Cu-Al2O3 and Au-Al2O3 systems. Finally it is noted that strong adhesion is produced when Al2O3 is subjected to preferential sputtering at the time of Cu deposition; the resulting interface chemistry is discussed.
Optical Behavior of Sputter-Deposited Aluminum Nitride: Relationship to Film Cheiistry
Authors: Kubiak C. J. G. , Aita C. R. , Hickernell F. S. , Joseph S. J. 
Published: March 2011

ABSTRACTFilms which are nominally aluminum nitride were grown by reactive sputter deposition using an aluminum target and rf-excited nitrogen discharges operated at power levels from 100 to 800W. Depositions were made on water-cooled (111)-cut Si and amorphous quartz substrates. The optical behavior of these films and its relationship to chemistry is discussed in the present paper.
Photo-Induced Excess Conductivity in Doping Modulated Amorphous Semiconductors
Authors: Kakalios J. , Fritzsche H. 
Published: March 2011

AbstractThe metastable excess conductivity σ(E) observed in hydrogenated amorphous silicon (a-Si:H), that is alternately doped n- and p- type, is compared with the Staebler-Wronski effect and other metastable conductivity changes observed in compensated a-Si:H and in oxidized p- type a-Si:H respectively. We find that Dohler's model of electron-hole pair separation in the pn-junction fields cannot account for the long life of a(E) near and above 300ºK. A defect complex associated with boron having a large configurational relaxation after releasing an electron by photoexcitation is considered as an explanation for σ(E).
Bonding and Release of Hydrogen in a-Si:C:H Alloys
Authors: Beyer W. , Wagner H. , Mell H. 
Published: March 2011

AbstractHydrogen evolution and infrared absorption studies of a-Si:C:H films prepared from mixtures of hydrocarbon (CH4' C2H6' C2H4) and silane gases (SiH4 'Si2H6)by the glow-discharge process show that both the absolute hydrogen content and the hydrogen bonding is uniquely determined by the carbon content. Up to a carbon concentration of ∼45 % the widening of the optical gap is mainly due to an increase of the hydrogen content. For a hydrogen density NH > 1- 2x1022cm-3 the incorporated hydrogen atoms lead to the formation of voids, resulting in thermal instability of the bonded hydrogen and in a deterioration of the electronic quality of the amorphous material.
Gap States in Hydrogenated Amorphous Silicon—Carbon Alloys
Authors: Fiorini P. , Evangelisti F. , Frova A. 
Published: March 2011

AbstractTail and defect states in the gap of a-SixCl-x:H alloys have been studied by measurements of spectral photoconductivity. The variation of defect—state density versus x is found to be negligible. By comparison with PDS results the ητ product has been determined and found to be almost independent of photonenergy and to strongly decrease with inclusion of carbon. This effect is attributed to changes in the transport mechanism combined with an increased recombination rate associated with the widening of the gap.
The First Tetrahedrally Bonded Diamond–Like Compounds with Metallic Conductivity
Authors: Sawan Y. 
Published: March 2011

AbstractIn this paper we report for the first time the discovery of metallic conductivity in some tetrahedrally bonded diamond–like ternary oompounds 1 v vl with the general formula A3B C4 · Such compounds are characterized by a Valence Electron Concentration (VEC) of four valence electrons per atom. The preparation and characterization of one of the investigated compounds Cu3AsSe4 will be presented.The transition metal atoms in such a compound are connected by non-transition metal atoms (Se) via coordinate locallized bonds in a tetrahedral environment. Such an environment should lead to a splitting in the 3d filled orbitals of the transition metal because of lattice field. A delocalization of the 3d electrons is expected to take place via back donation, through an overlap with the empty antibonding orbitals on the non-metal atoms to minimize the negative formal charge on the transition metal atoms. If such an overlap leads to continuous electron path through the whole material, metallic conductivity could be visualized. The detailed bonding model will be discussed.
Critical Materials Parameters for the Development of Amorphous Silicon Alloys
Authors: Ovshinsky Stanford R. , Adler David 
Published: March 2011

AbstractThe desired properties of solar cells are discussed, and a relative figure of merit for the comparison of cells fabricated using different technologies is described. The advantages of utilizing amorphous silicon alloys as the active material in solar cells are enumerated. Selected materials properties of these alloys are described and the physics of their electronic structure is discussed in detail. The necessary steps for achieving commercially viable cells based on amorphous silicon alloys are listed, and it is demonstrated how each of them has been achieved using a technology that incorporates fluorine throughout the entire process. The chemical and physical basis for the superiority of fluorinated material is presented in detail. Continuous web large-area high-efficiency multijunction solar cells are in production. Dual band gap multijunction cells have been tested under continuous air mass 1 exposure for over 2000 hours and show essentially no degradation. Some recent results are presented.
Thin Film Silicon Power Modules: Challenges and Opportunities for Materials Science
Authors: Morel Don L. 
Published: March 2011

AbstractA survey of the materials issues involved in the development of thin film Si:H power modules is presented. Though there are significant opportunities for advancement of Si:H itself, especially in terms of new alloys, the range of opportunities is extended dramatically when all aspects of the product -- from gaseous fuels through encapsulants -- are included. Examples from each of these areas are presented to Indicate the current state of development as well as the needs for the future. Viable products exist today, but the extent of greater success depends critically on materials innovation.
Stability of P-I-N Amorphous Silicon Solar Cells with Boron-Doped and Undoped I-Layers
Authors: Catalano Anthony , Arya Rajeewa R. , Kerns Ralph C. 
Published: March 2011

AbstractBoron-doping the i-layer in p-i-n amorphous silicon solar cells improves the device performance when the density of impurities in the undoped i-layer material is high (< 1020 cm-3). While this technique can boost the initial device efficiencies for poor quality i-layer material, our devices degrade faster than devices made with undoped, low impurity i-layer material. We have measured the degradation of photovoltaic parameters as a function of continuous AM1 exposure time for devices with and without B-doped i-layers. For single junction p-i-n solar cells with comparable initial conversion efficiencies (< 7%, area < 1cm2) we find that our devices containing i-layers deposited from gas mixtures containing 2–3 ppm diborane degrade faster than devices containing undoped i-layers. Similar effects are observed when two-junction stacked cells with B-doped i-layers are compared to two-junction stacked cells with undoped i-layers.
Experimental and Theoretical Analysis of the above Threshold Characteristics of Amorphous Silicon Alloy Field Effect Transistors
Authors: Hack M. , Shur M. , Hyun C. , Yaniv Z. , Cannella V. , Yang M. 
Published: March 2011

AbstractExperimental studies on the above threshold characteristics of amorphous silicon alloy thin films transistors show that the field-effect mobility has a weak temperature dependence and that the current-voltage characteristics are described by a power law dependence on gate voltage, with an exponent greater than two. These results are in good agreement with our theoretical model, which demonstrates that in the above threshold regime, the Fermi level at the semiconductor-insulator interface lies in the tail states which control device performance. Analysis of the above threshold characteristics shows the characteristic energy variation of the exponential tail state distribution to be ∼22meV and that the on current changes by a factor of only two over the temperature range lO−90°C.
Characteristics of the Blocking Layers in the a-Si:H Photoreceptor
Authors: Kakinuma H. , Nishikawa S. , Watanabe T. , Nihei K. 
Published: March 2011

AbstractThe effects of characteristics of the blocking layers in multilayered a-Si:H photoreceptors on electrophotographic properties are reported. The structure of the photoreceptor is Al/a-Si:H(p)/a-Si:H(i)/a-Si1−xCx. The thickness and boron doping ratio of the bottom p-type layer and the thickness and compositional fraction x of the surface a-Si1−xCx layer are varied. It is shown that the dark decay time is particularly sensitive to the thickness and doping ratio of the p-type layer. These dependences are discussed assuming a space charge layer in the p-type layer. It is also shown that the thickness and x of the a-Si1−xCx layer greatly influence the residual voltage and effective quantum efficiency of photocarrier generation.
High Performance Polycrystalline Silicon Thin Film Devices
Authors: Hawkins William G. 
Published: March 2011

AbstractThe goal of this work was to produce a fabrication process for high performance polycrystalline silicon thin film MOS devices. We have fabricated p-channel devices with mobilities of 35 cm2/V-sec and n-channel devices with mobilities of 50 cm2/V-sec by tailoring the process for depositon of the channel layer, by gate oxidation of the channel at high temperature, and by use of plasma hydrogenation. Under optimal conditions deduced from the study, device threshold voltages are close to zero. Leakage currents in the off-state are less than 0.1 pA/µm of channel length. Fabrication of the devices requires four mask levels and employs standard process steps. Therefore, polycrystalline silicon devices are attractive candidates for a variety of electronics applications, including thin film logic over large area.
Highly Conductive and Wide Band GaP Microcrystalline Silicon Films Prepared by Photochemical Vapor Deposition and Applications to Devices
Authors: Nishida S. , Tasaki H. , Konagai M. , Takahashi K. 
Published: March 2011

AbstractDoped hydrogenated microcrystalline silicon (μc-Si:H) and fluorinated hydrogenated microcrystalline (μc-Si:F:H) films were prepared by the mercury photosensitized decomposition of a disilane-hydrogen or a difluorosilane-hydrogen gas mixture, respectively. The maximum dark conductivity and optical band gap of μc-Si:H films were respectively 20 S•cm−1 and ∼2.0 eV for n-type and 1 S•cm−1 and 2.3 eV for p-type. A higher dark conductivity as much as 50 S•cm−1 and a wide gap of 2.0 eV were obtained for n-type μc-Si:F:H. It is most significant that the gaseous ratio of hydrogen to disilane should be enhanced to obtain such a highly conductive and wide gap film. The crystallinity of the photo-deposited μc-Si:H films appeared to be improved in comparison with that of films by the conventional plasma glow discharge technique.
Selected Area Epitaxial Regrowth of Amorphous Si/(100) Si Structures by Laser Annealing
Authors: Christou A. , Varmazis C. , Efthimiopoulos T. , Fotakis C. 
Published: March 2011

AbstractExcimer laser KrF (248 nm) annealing at 93 mj/cm2 and 175 mJ/cm2 has been found to recrystallize amorphous silicon on (100)Si. The major impurities introduced by excimer laser annealing are carbon, while surface roughness remains as a major problem. Channel mobilities measured on MOSFETs processed on epitaxially regrown silicon were 98-115 cm2/v.s. Leakage currents between recrystallized silicon regions were 1-2 uA/cm2.
Determination of Density of Localized States in Amorphous Silicon Alloys From the Low Field Conductance of Thin N-I-N Diodes
Authors: Shur Michael , Hack Michael 
Published: March 2011

AbstractWe describe a new technique to determine the bulk density of localized states in the energy gap of amorphous silicon alloys from the temperature dependence of the low field conductance of n-i-n diodes. This new technique allows us to determine the bulk density of states in the centre of a device, and is very straightforward, involving fewer assumptions than other established techniques. Varying the intrinsic layer thickness allows us to measure the,density of states within approximately 400 meV of midgap.We measured the temperature dependence of the low field conductance of an amorphous silicon alloy n-i-n diode with an intrinsic layer thjckness of 0.45 microns and deduced the density of localised states to be 3xlO16cm−3 eV−1 at approximately 0.5 eV below the bottom of the conduction band. We have also considered the high bias region (the space charge limited current regime) and proposed an interpolation formula which describes the current-voltage characteristics of these structures at all biases and agrees well with our computer simulation based on the solution of the complete system of transport equations.
Light Effects on Grain Boundary Properties in Silicon
Authors: Cheng L. J. , Shyu C. M. 
Published: March 2011

ABSTRACTWe have studied the photoconductivity of grain boundaries in p–type silicon. The result demonstrates the applicability of the technique for the measurement of minority carrier recombination velocity at the grain boundary. The experimental data are consistent with the thought that the recombination velocity increases with the boundary state density and light intensity.
Effects of Grain Boundaries in GaAs Solar Cells
Authors: Benner John P. , Eugene Blakeslee A. 
Published: March 2011

ABSTRACTMany problems exist in current attempts to develop polycrystalline GaAs as a basis for thin-film solar cells. Some of these problems arise from the direct interaction of carriers, both dark and photo-generated, with grain boundaries. Others are more indirect; e.g., shunting currents due to the grain boundary-enhanced diffusion of contaminating impurities. This paper describes several of these effects, including the influence of system chemistry on grain properties, the correlation of device parameters with grain size, and grain boundary passivation experiments. A review of various approaches to solving the problems confronting the field is given, and an attempt is made to interpret reported observations in terms of existing theoretical models.
High-Spatial-Resolution Diffusion Length Measurements in Polycrystalline GaAs
Authors: Fletcher Robert M. , Ken Wagner D. , Wicks G. W. , Ballantyne J. M. 
Published: March 2011

ABSTRACTA technique for making rapidly-scanned, high-spatial resolution measurements of minority-carrier diffusion length is applied to the characterization of polycrystalline GaAs. Measurements on a large-grained n-type epitaxial layer show gradual variations of hole diffusion length from 0.1µm to l.lµm across the wafer as well as occasional small step changes at grain boundaries. By trading resolution for speed, the technique would be well suited to the nondestructive evaluation of large-area epitaxial layers.
Advantages of MIS Processing on Passivated Polycrystalline Silicon
Authors: Rajeswaran G. , Thayer M. , Rao V. J. , Anderson W. A. 
Published: March 2011

ABSTRACTWacker polycrystalline silicon shows enhanced grain boundary activity after a high temperature (950° C) anneal. It is possible to passivate this effect in a hydrogen plasma. The low temperature (600° C) processing of MIS technology does not activate grain boundaries or deteriorate a passivated specimen. Activated grain boundaries with MIS structures can be used to assess the character of recombination currents. It is concluded that MIS processing is advantageous for passivated polycrystalline silicon.
Potential Applications of Poly-Silicon as an Electronic-Device Material
Authors: Bartelink Dirk J. 
Published: March 2011

ABSTRACTPoly-crystalline silicon can be regarded as a true electronic material if good p-n junctions can be made in it or if its state of depletion can be altered by reasonable gate voltages. The degree of perfection with which it must exhibit these electronic-material properties depends on whether the application is as a technology in VLSI (or other bulk-Si substrate use) where devices with bulk-crystalline properties are available or as the principal active material in Large Area Integration (LAI), such as flat-panel display addressing circuits, where the competition is much less demanding. The three main detrimental effects of grain boundaries on electronic-device function are the action of grain boundary traps as (1) extra charge centers, (2) lifetime killers, and (3) mobility-reducing scattering centers. The current trend in reducing or almost eliminating grain boundaries by laser recrystallization or lateral epitaxy has the effect of reducing the average number of traps. In terms of potential applications of the material, the improvement derived from these procedures must be balanced against other contraints placed on the overall structure. For example, the thickness and quality of the lower oxide (and interface) in these processes will determine whether an electronically active lower gate function is practical. Some currently envisioned applications include load devices in inverters either as resistors or as depletion transistors, common-gate staked CMOS structures, dual-channel MOSFET's, and other “vertical VLSI” applications. The systems-level topological advantages of stacked structures and the circuit-performance improvement provided by the ground plane in dielectrically isolated devices must also be balanced against the extra cost and yield loss of additional masking level complexity and design complication.
Electrical Properties of ZnO-Bi2O3 Metal Oxide Heterojunction — A Clue of a Role of Intergranular Layers in ZnO Varistors
Authors: Eda Kazuo 
Published: March 2011

ABSTRACTZinc Oxide (ZnO) Ceramics-Bismuth Oxide (Bi2O3) Metal Oxide thin film heterojunction made by sputtering technique showed a highly non-Ohmic property. The voltage-current characteristics and the dielectric properties showed dependence on Bi2O3 metal oxide thin film thickness.In this paper after reviewing and discussing the electrical properties of ZnO varistors, the role of intergranular layers in the ZnO varistor is discussed based on experimental results with the heterojunction.
Preparation of Oriented GaAs Bicrystal Layers by Vapor-Phase Epitaxy Using Lateral Overgrowth
Authors: Salerno Jack P. , Mcclelland R. W. , Vohl P. , Fan John C. C. , Macropoulos W. , Bozler C. O. , Witt A. F. 
Published: March 2011

ABSTRACTThis paper describes a novel technique that utilizes vapor-phase epitaxy to grow bicrystal semiconductor layers with predetermined rotation axis, misorientation angle, and grain boundary plane. The geometrical structure of the grain boundary in each layer is therefore completely specified. The technique has been demonstrated by using the AsCl3-GaAs-H2 method to grow a series of GaAs bicrystals, each containing a [110] tilt boundary formed by a grain with a (111)B boundary plane and a grain rotated from (111)B by a selected misorientation angle. The results of initial electrical measurements indicate that the height of the potential barrier associated with each grain boundary varies with the misorientation angle.
The Electronic Properties Of Semiconductor Grain Boundaries
Authors: Seager C. H. 
Published: March 2011

ABSTRACTGrain boundaries play an important role in determining the operating characteristics of devices such as varistors and thin film solar cells and transistors. In the last several years detailed one-electron expressions have been developed for the transport coefficients of majority and minority carriers at grain boundaries. These theories have been successful in predicting the measured electrical properties of bicrystals in lightly doped silicon. The status of our understanding in this area will be reviewed in some detail. Recent extensions of these calculations which have been necessary to explain measurements on grain boundaries in degenerately doped GaAs will also be reviewed.