bluuebunny/crossref_metadata_2025_split huggingface dataset:
Submicron P-Channel Mos Devices with Boron Doped Polysilicon Gates Fabricated by Rapid Thermal Processing
Authors: Kugelmass Sheldon M. , Krusius J. Peter 
Published: March 2011

AbstractA low thermal budget process is demonstrated for the fabrication of submicron Boron doped polysilicon gate p-channel MOS devices with ultra thin gate insulators. All critical processing steps with temperatures above 700 °C, including gate oxide growth and shallow source/drain junction formation, were performed by Rapid Thermal Processing (RTP). In situ doped polysilicon was used to eliminate the need for a high temperature drive-in step. Surface channel p-channel enhancement mode devices with excellent characteristics were fabricated to demonstrate the feasibility of this process.
The Electrical Properties of Polyoxide Depending on the Polycrystalline-Si Formation Conditions
Authors: Yi Kyoung-Soo , Cho Deok-Ho , Lee Jeong Yong , Nam Kee-Soo , Kang Sang-Won , Lee Jin-Hyo 
Published: March 2011

AbstractPrior to growth of polyoxide, amorphous-Si with a cap of low temperature oxide was annealed to improve the dielectric property of polyoxide. Current-electric field, critical electric field, critical electric field histogram, and Fowler-Nordheim conduction plot were evaluated. The interface of polyoxide and poly-Si was observed with a transmission electron microscope. The annealing of the amorphous-Si prior to oxidation was effective to improve the dielectric property of the polyoxide.
Thickness Effects on the Activation Energy of Source-Drain Current in P and N Channel Polycrystalline Silicon Thin Film Transistors
Authors: Khan Babar A. , Pandya Ranjana 
Published: March 2011

AbstractWe report activation energy measurements of the source-drain current of polysilicon thin film transistors (TFTs). We have shown earlier that measurements carried out on unhydrogenated TFTs can be explained by the presence of band tail states in addition to deep localized states. After hydrogenation, the density of band tail states is greatly reduced and the data can be fitted with only the deep states.In the present work we have studied both n and p channel TFTs. This was done by measuring both type of devices on the same wafer so that differences due to processing conditions could be ruled out. Both type of devices had intentionally undoped channels and were identical except for the n or p type source-drain regions. The thinner TFTs discussed in this work have a sharper drop in the activation energy than would be expected from idealized calculations. This sharp drop in activation energy is also an indication of a sharp subthreshold slope. This decrease in subthreshold slope (Volts/decade) is due to the complete depletion of the channel polysilicon, which leads to a rapid increase (or decrease) in the surface potential as a function of the gate voltage.
Defect Passivation Kinetics and Small Geometry Effects in Polysilicon Thin Film Transistors
Authors: Wu I-Wei , Huang Tiao , Lewis Alan G. , Jackson Warren B. , Chiang Anne 
Published: March 2011

AbstractThe effects of hydrogen plasma passivation on n-channel polycrystalline silicon thin film transistors fabricated with a maximum temperature of 600°C are investigated. It is found that charge, sharing, avalanche multiplication, grain size, and gate edge in-situ passivation or even partial hydrogenation can all contribute to the small geometry effect. At low drain bias, the channel charges supported by the source and drain fringing fields cause threshold shifts for short channel devices; at high drain bias avalanche multiplication is the dominant effect. The charge sharing effect may be related to the unpassivated trap-states in the channel since thresholds of fully hydrogenated devices became independent of channel length at low drain bias. The threshold shifts of narrow width devices were also diminished with increasing hydrogenation time. An anomalous turnaround effect of the field effect mobility in saturation regime for the short channel devices is observed near saturated hydrogenation. This effect is probably due to the passivation of back-channel defects and the reduction in impact ionization rate by hydrogenation. Saturated hydrogenation not only improves device performance but also reduces small geometry effects. Avalanche multiplication remains the dominant mechanism for short channel effect in the saturated hydrogenated devices.
High Resolution Transmission Electron Microscope Study of UHV Deposited Titanium Thin Films on (001), (III) and (011)Si
Authors: Wang M. H. , Chen L. J. 
Published: March 2011

AbstractHigh resolution transmission electron microscopy has been applied to study the formation of amorphous interlayers by solid-state diffusion in ultrahigh vacuum deposited Ti thin films on (001), (111) and (011)SiThe interface structures of as deposited and annealed samples were examined. The disordered regions at the a-interlayer/c-Si interfaces were found to be most and least extensive in (011) and (111) samples, respectively. Growth behaviors of a-interlayers are described. The amorphization appeared to be initiated at the grain boundaries of Ti thin films. Ti5 Si3 was identified to be the phase formed at the initial stage of the interfacial reactions by HREM in conjunction with the optical diffraction.
SiO2/Si Interfaces Studied by Stm and Hrtem
Authors: Niwa Masaaki , Onoda Minoru , Iwasaki Hiroshi , Sinclair Robert 
Published: March 2011

AbstractThe morphology of SiO2/Si interfaces in a semiconductor LOCOS active area grown by several oxidation conditions has been studied, to compare the roughness of the interfaces observed by STM and HRTEM in particular. Samples consisted of typical MOS structures with a polysilicon gate/SiO2/Si(100). Hydrogen terminated Si surfaces were prepared by means of HF dipping for STM observations. The interface roughness of a “dry” oxide observed by HRTEM was slightly larger than that of a “wet” oxide. Good agreement could be found between STM and HRTEM for the wet oxide interfaces. As for the dry oxide interface, it was more difficult to obtain a reproducible STM image than for the wet oxide interface, but the reverse was true for HRTEM. During the HRTEM, high energy electrons damage the sample and reduce the oxide thickness, especially in the wet oxide samples.
The Study of Defects in Metals Using High Resolution Transmission Electron Microscopy and Atomistic Calculations
Authors: Mills M. J. , Daw M. S. 
Published: March 2011

AbstractThe coupling of HRTEM with atomistic calculations is described for the study of grain boundaries and dislocations in aluminum. HRTEM images of the Σ9 (221) [110] grain boundary are compared with molecular statics calculations using both the Embedded Atom Method (EAM) and two pair potentials. Comparison between observed and simulated images are shown to serve as a stringent test of the theoretical methods. Atomistic calculations can in turn provide threedimensional information about the defect structure. Using the EAM, it is also possible to account for the effects of thin foil geometries on the minimim energy configuration of defects. While these effects are found to be minimal for grain boundary structures, the influence of the thin-foil geometries on the core structure of the 60° dislocation in aluminum is discussed. These comparisons indicate that the EAM function provides a good description of grain boundary structures, but fails to reproduce the observed dislocation core structure due to a low predicted value of the intrinsic stacking fault energy (SFE) on the (111). In contrast, the pair potentials used in this study provide reasonable SFE values, but appear to be less accurate for the prediction of the Σ9 (221) [110] grain boundary structures.
Anti-Site Bonds and the Structure of Interfaces in SiC
Authors: Pirouz P. , Yang J. 
Published: March 2011

AbstractHigh resolution electron microscopy has been used to study the structure of the 3C/6H interface, Σ,=3 {111}and Σ.=3 {112}grain boundaries in 3C-SiC. In SiC, as in other compound semiconductors, anti-site bonds occur in a variety of defects. These are high energy bonds comparable to that of dangling bonds. But, while dangling bonds at the grain boundaries may be eliminated by reconstruction just as in elemental semiconductors, it may not be possible to avoid anti-site bonds.These problems are discussed for the Σ=3 {112} grain boundary, where the structures proposed for Ge and Si are used as starting models for SiC.
High Resolution Transmission Electron Microscopy of GaAs/AlAs Hetero-Structures in the <110> Projection
Authors: Ikarashi N. , Sakai A. , Baba T. , Ishida K. , Motohisa J. , Sakaki H. 
Published: March 2011

AbstractHigh resolution transmission electron microscopy (HRTEM) of GaAs/AlAs hetero-structures grown by molecular beam epitaxy (MBE) is carried out in the <110> projection. It is shown that GaAs and AlAs are distinguished clearly by the difference in their lattice images at the samples thicknesses of about 15–30 nm under near Scherzer focus condition. Under these imaging conditions, very thin films consist of single monolayer AlAs are observed. Vicinal interfaces of GaAs/AlAs which were grown on (001) substrate misoriented toward [110] are also examined in the [110] projection. The interfacial structures are imaged edgeon, so that the fluctuations of terrace width, and the roughness of step-edges at these interfaces are observed on an atomic scale.
Incoherent Imaging of Materials Structure and Composition by Z-Contrast Stem
Authors: Pennycook S. J. , Jesson D. E. , Chisholm M. F. 
Published: March 2011

AbstractIt is shown how the use of a high angle annular detector in a STEM provides images which show strong compositional sensitivity and almost perfect incoherent characteristics. No contrast reversals occur with defocus or sample thickness and the contribution of an atomic string is insensitive to the distribution and strength of neighboring strings. The image is best described in real space as a simple convolution of the incident probe intensity profile with an object function sharply peaked at the atomic strings having a strength dependent on composition. How the incoherent characteristics arise is described using a Bloch wave approach and examples are shown of interfaces in semiconductor and superconductor materials.
“Column-By-Column” Compositional Mapping At Semiconductor Interfaces Using Z-Contrast Stem
Authors: Jesson D. E. , Pennycook S. J. , Baribeau J. -M. 
Published: March 2011

AbstractA new strategy for atomic resolution compositional mapping at semiconductor interfaces is presented. Images can be interpreted directly to within 10% to give column-by-column compositional information with a sensitivity approaching Rutherford scattering cross sections. We apply the method to obtain the first atomic resolution images of interfacial ordering in ultrathin (SimGen)p superlattices and attribute the results to growth on (2 × 1) and (1 × 2) reconstructed surfaces.
High-Resolution Electron Microscopy of Planar Defects in Ain.
Authors: Mckernan Stuart , Norton M. Grant , Carter C. Barry 
Published: March 2011

AbstractThe defects which occur in polycrystalline aluminum nitride are very detrimental to the beneficial physical and electrical properties. 'Dome-like' or 'D' defects, consisting of a flat basal fault joined to a curved planar fault, are examined by high-resolution electron microscopy. The basal segments are shown to contain a thin ∼5Å layer of a second phase and are associated with a stacking-fault and an antiphase boundary. A structural model is proposed for the defect which incorporates a layer of alumina at the basal segment of the 'D' defect. The formation of thisdefect is discussed.
High-Resolution Electron Microscopy Studies of Faults and Intergrowth in Nb3O7F
Authors: permér Lotta , Lundberg Monica 
Published: March 2011

AbstractHREM studies of the low-pressure form of Nb3O7F, obtained by thermal decomposition of NbO2F or by reacting stoichiometric amounts of NbO2F and Nb2O5, confirmed that the crystals are built up of a shear-type structure in which slabs of ReO3 type, infinite in two dimensions and three octahedra wide, separate the shear planes. Most of the crystals were well-ordered, although faults could occasionally be detected. However, some crystals were found to be intergrown with a structure closely related to the high-pressure form of Nb3O7F. The latter structure is composed of wavy rows of edge-sharing NbX7 pentagonal bipyramids, joined to each other by NbX6 octahedra. The connection between the two atomic arrangements can be understood in terms of the common c-axes and a slight distortion of the polyhedra along the boundary.
Hrem of Defects in Oxide Superconductors
Authors: Zandbergen H. W. , van Tendeloo G. 
Published: March 2011

AbstractA review is given of defects occurring in the superconducting oxides YBa2Cu3O7, (Bi,Tl)2(Sr,Ba)2CanCul+nO6+2n, and Pb2Sr2(Cal-xYx)nCu2+nO6+2n+∂. A number of these defect structures correspond to other thermodynamically stable phases. The observations of these defects have led in several cases to successful synthesis of new superconducting compounds. Defects can effect the superconducting properties, which they can either deteriorate (weak links) or improve (flux pinning). Both effects are considered.
HREM of Epitaxial YBa2Cu3O7 Thin Films
Authors: Mitchell T. E. , Basu S. N. , Nastasi M. , Roy T. 
Published: March 2011

AbstractThin films of YBa2Cu3O7 have been prepared by evaporation of Cu, Y and BaF2 onto (001) SrTiO3, LaGaO3. and LaAlO3 and subsequent annealing. Their microstructures have been examined by HREM of cross-sectional specimens. Epitaxial (001) grains of YBa2Cu3O7 form near the substrate interface in thin films but (001) and (010) grains tend to nucleate as the film thickens. 90° grain boundaries are therefore common, as well as other defects such as small-angle boundaries, dislocations and stacking faults. HREM of the substrate/superconductor interface indicates regions of perfect epitaxy, highly distorted areas, amorphous regions and areas showing evidence of interdiffusion. The relationship of these microstructural features to critical current density is discussed.
Morphology and Defect Structure of Sputtered High-Quality In-Situ YBa2Cu3O7−δ Films
Authors: Streiffer S. K. , Lairson B. M. , Eom C. B. , Marshallt A. F. , Bravman J. C. , Geballe T. H. 
Published: March 2011

AbstractTransmission Electron Microscopy has been used to study the morphology and defect structure of sharp superconducting transition, high (2-6 ×107 A/cm2) critical current YBa2Cu3O7−δ films on MgO substrates. These were oriented such that the unit cell axes of the film aligned with those of the substrate, with some domains obeying a second orientation relationship rotated by 45° in the plane of the film, i.e. film <110> parallel to substrate <100>. The latter is not expected from simple lattice matching considerations. A strong influence of substrate surface topography on film microstructure was noted, leading to a high density of out-of-phase, low-angle tilt, and other boundaries near the substrate-film interface, which decreased with increasing distance from the substrate. Finally, the effects on film microstructure of two variables of specific interest in our sputtering system were investigated: the thickness of the deposited film, and the temperature at which a high oxygen pressure (500 torr) is introduced after deposition is complete. Increases in film thickness resulted in longer, more widely spaced twins, whereas lower oxygenation temperatures resulted in shorter twins.
Determination of the Formation of the 1/6[031] Extrinsic Stacking Faults in Deformed YBa2Cu3O7−δ
Authors: Kramer M. J. , Kvam E. P. , Chumbley L. S. 
Published: March 2011

AbstractMechanial deformation of the YBa2Cu3O7−δ high temperature superconductor under a number of different processing conditions resulted in the formation of <100> and <110> edge dislocations, both having a (001) slip plane. Subsequent high temperature annealing at 900°C resulted in the formation of extrinsic stacking faults with a large separation of the partial dislocations, up to 0.35 μm, suggesting a very low minimum stacking fault energy of 1.2 × 10−2 J/m2. High resolution transmission electron microscopy (HRTEM) in conjunction with image simulations revealed that the stacking faults were comprised of an extra CuO plane between the Ba layers with an offset of b/2. The stacking fault vector of 1/6[031] requires some separation of the <010> Burgers vectors into the c-axis direction. A model in which [010] separates into 1/6[031] + 1/[031] is consistent with the observed stacking faults.
Structure and Defects of Shock-Processed Ti and Y-Based Copper Oxide Superconductors
Authors: Sharma R. , Ramakrishna B. L. , Iqbal Z. , Thadhani N. N. , Chawla N. 
Published: March 2011

AbstractWe have studied the micro-structure of shock synthesized Tl2Ba2CuO6, shockprocessed YBa2Cu3O7 and 10% Ag-YBa2Cu3O7. The structural interpretation of the defects observed in these materials is discussed and compared with computer simulated images. Two planar defects with a stacking sequence of Cu-Ba-Tl-Ba-Cu and Cu-Ba-Tl-Tl-Ba-Cu-Tl-Cu-Ba-Tl-Tl-Ba-Cu in the Tl based oxide and a new defect sequence of Cu-Ba-Cu-Y-Y-Cu-Ba-Cu in the Y based oxides are reported here. An attempt is made to relate the change in superconducting properties observed to the defect structure present.
Relation between Leakage Current in PIN Photodiodes and Defects in InGaAs(P)/InP Heterostructures Grown Low Pressure MOCVD
Authors: Knight D. G. , Miner C. J. , Springthorpe A. J. 
Published: March 2011

ABSTRACTHigh resolution maps of the InGaAs photoluminescence intensity over whole 50mm diameter PIN detector wafers grown by low pressure MOCVD were obtained using a scanning photoluminescence (PL) system. The leakage current of PIN detectors was found to decrease exponentially with increased PL intensity. This correlation was quantitatively valid for both variation on a given wafer and for wafer-to-wafer variations. The density of morphological features on the surface of InGaAs(P)/InP heterostructures also was found to decrease exponentially with increased PL intensity, where a simple linear relationship between leakage current and feature density was then determined. The features are likely a manifestation of substrate defects which propagate from the surface of poor quality substrates.
Atomic Diffusion With Strain and Injection
Authors: Vechten J. A. Van 
Published: March 2011

ABSTRACTThe inherent complexity of defect processes in III-V's and the consequent difficulties with ab initio and semi-empirical methods are recalled. A potential solution using massive Monte Carlo simulation on microcomputers is suggested. Evidence for the validity of the Ballistic Model, BM, of atomic diffusion in III-V's is noted. According to the BM the effect of strain (in the absence of any electrostatic, population, or recombination effect) is to increase the rate at which a given mobile atom hops where the sample is compressed. For the case of misfit strain at a (100) junction, we note that the anisotropy of the elastic constants implies that some planes running into the bulk will be compressed whichever the sign of the misfit. This implies that misfit strain of either sign should increase the observed rate of interdiffusion, in the absence of other effects. We also recall the importance (demonstrated at low T) of recombination enhancement of atomic diffusion, RED. Devices are processed at temperatures where the thermal rate of recombination is very high and often operated at high levels of injection. The interaction of strain with RED is clearly important and complicated. III-V crystals have the further complication of being piezoelectric. The active piezoelectric axes are <111>, so a pure <100> strain does not produce a field. However, the accommodation a device makes to misfit at (100) junctions can generate a strong field, which may fluctuate with bias voltage.
Consequences of Strain and Growth Kinetics on Growth Modes and Dislocation Formation in Strained Layer Epitaxy
Authors: Singh Jasprit 
Published: March 2011

ABSTRACTWe examine the growth modes of compound semiconductors grown by molecular beam epitaxy in lattice matched and strained layers. While in lattice matched layers it is possible to grow in the layer by layer mode by choosing proper growth conditions, in strained layers we find that for large strain, it is not possible to do so. This is due to the competition between surface strain energy which favors 3D growth and surface chemical energy which favors a layer by layer growth mode. The growth mode is shown to have significant effects on the nature of the dislocations generated beyond critical thickness.
Reliable Metallization for Inp-Based Devices and Oeic's
Authors: Wada O. , Ueda O. 
Published: March 2011

ABSTRACTWe describe techniques of reliable metallization in InP-based systems for application to discrete and opto-electronic integrated circuits (OEIC's). Strong metallurgical interaction between Au and InP-based compounds can cause serious contact degradation in light emitting diodes (LED's). By analyzing this interaction in detail, an improved thin Au/Zn/Au p-contact technique has been developed. The results are compared with Pt/Ti contacts, and it has shown that both provide sufficient reliability under temperature and current stresses in LED's. We then describe a metallization technique for flip-chip bonding of opto-electronic devices on other semiconductor chips for OEIC applications. An acceptable reaction barrier effect of Pt in AuSn/Pt/Ti metallization structure has been demonstrated and this structure has been used for a high-reliability, flip-chip integrated GaInAs/InP PIN photodiode/GaAs amplifier receiver circuit. We also discuss requirements for metallization for future monolithic OEIC's by taking up an example of metal-semiconductor-metal photodiodes in InP-based systems.
Thermal Behaviour of Au/Pd/Gaas Contacts
Authors: Pécz B. , Veresegyházy R. , Mojzes I. , Radnóczi G. , Sulyok A. , Malina V. 
Published: March 2011

ABSTRACTAu(85nm)/Pd(55nm)/GaAs(100) samples were heat treated in the 325–425°C temperature range. The annealed samples have been investigated using Rutherford Backscattering Spectrometry, Auger Electron Spectroscopy and Transmission Electron Microscopy. The gold layer remained largely unreacted up to 300°C. Significant Pd diffusion into GaAs consuming a 50–60 nm thick layer of GaAs is evident in the case of sample annealed at 325°C and a slight Au diffusion is also noticeable. In the sample annealed at 350°C the spreading of palladium was very quick. A strong reaction took place between the GaAs and the metallization in the case of sample heat treated at 375°C. At this temperature we have identified the PdGa phase using electron diffraction.
Thermoelectric Power in Quantum Confined Optoelectronic Materials under Classically Large Magnetic Field
Authors: Ghatak Kamakhya P. , De B. , Mondal M. , Biswas S. N. 
Published: March 2011

ABSTRACTWe shall study the thermoelectric power under classically large magnetic field (TPM) in optoelectronic materials of quantum wells (QWs), quantum well wires (QWW's), quantum dots (QDs) and compare the same with the bulk specimens of optoelectronic materials by formulating the respective electron dispersion law. The TPM increases with decreasing electron concentration in an oscillatory manner in all the cases, taking n-Hg1−xCdxTe as an example. The TPM in QD is greatest and the least for quantum wells respectively. The thecoretical results are in agreement with the experimental observations as reported elsewhere.