bluuebunny/crossref_metadata_2025_split huggingface dataset:
CdS and CdTe Large Area Thin Films Processed by Radio-Frequency Planar-Magnetron Sputtering
Authors: Hernández-Contreras H. , Contreras-Puente G. , Aguilar-Hernández J. , Morales-Acevedo A. , Vidal-Larramendi J. , Vigil-Galan O. 
Published: April 2011

ABSTRACTThe processing of large area thin films solar cells represents a challenge, mainly due to the need for optimal setting of the critical growth parameters for scaling-up of the processes that guarantee homogeneous properties in the sub-minimodule architecture. We have been working with a Radio-Frequency Planar Magnetron Sputtering (RF-PMS) system, processing 450 cm2 areas of CdS and CdTe thin films grown on soda lime glasses and conducting glasses (SnO2:F-7ω/ ) for CdS, using for it a 6” balanced gun. The films have been processed with substrate temperatures (Ts) of 250°C, Ar chamber-pressure of 20 mTorr, and radio frequency power of 300 watts. The films were characterized by morphological, optical and electrical techniques, presenting in this work the corresponding measurements. Our results show that the better polycrystalline perfection, adherence and pinhole free films are obtained at substrate temperatures of 250°C.
Deep centers and fill factor losses in the CIGS devices
Authors: Igalson M. , Kubiaczyk A. , Zabierowski P. 
Published: April 2011

ABSTRACTThe influence of non-equilibrium space charge distributions on the fill factor of ZnO/CdS/Cu(In,Ga)Se2 photovoltaic devices has been investigated. Metastable changes of the amount of charge captured in deep levels have been produced by red or white illumination. Subsequent characterization by current-voltage, capacitance-voltage and admittance spectroscopy has been conducted at low temperature. The fill factor increases after a white light soaking and decreases after illumination of the reverse-biased device with red light at low temperature. This effect has been attributed to the metastable change of net doping concentration in the p+ layer of absorber close to interface. Blue light, absorbed in CdS provides holes to that region neutralizing the negative charge and thus improving the fill factor. The defects responsible for the interface-related metastability are in our opinion the same as those causing the persistent increase of the net doping concentration in the bulk of Cu(In,Ga)Se2 and seem to be related to selenium vacancies.
Direct Formation of C54 Phase on the Basis of C40 TiSi2 and Its Applications in Deep Sub-Micron Technology
Authors: Chen S. Y. , Shen Z. X. , Xu S. Y. , See A. K. , Chan L. H. , Li W. S. 
Published: April 2011

ABSTRACTA simple and novel salicidation process applying pulsed laser annealing as the first annealing step was used to induce TiSi2 formation. Both Raman spectroscopy and transmission electron microscope results confirm the formation of a new phase of Ti disilicide, the pure C40 TiSi2 after laser irradiation. Direct C54 phase growth on the basis of C40 template bypassing the C49 phase is accomplished at the second annealing temperature as low as 600°C. Line width independent formation of the C54 phase was observed on patterned wafers using this salicidation process and “fine line effect” is thus eliminated.
Electrical and Structural Properties of Catalytic-Nitrided SiO2 Films
Authors: Izumi Akira , Sato Hidekazu , Matsumura Hideki 
Published: April 2011

ABSTRACTThis paper reports structural and electrical properties of catalytic-nitrided silicon dioxide (SiO2) films. The surface of SiO2/Si(100) was nitrided at temperatures below 573 K. It was found that the incorporated N atoms are bound to Si atoms and O atoms and located on the top-surface of SiO2. Catalytic-nitrided SiO2 films have small amounts of Si-OH bonds and adequate resistance to boron (B) penetration.
TEM Study of strain states in III-V semiconductor epitaxial layers.
Authors: ROCHER André , PONCHET Anne , BLANC Stéphanie , FONTAINE Chantal 
Published: April 2011

ABSTRACTThe strain states induced by a lattice mismatch in epitaxial systems have been studied by Transmission Electron Microscopy (TEM) using the moiré fringe technique on plane view samples. For the GaSb/(001)GaAs system, moiré patterns suggest that the GaSb layer is free of stress and homogeneously relaxed by a perfect square array of Lomer dislocations. A 10 nm thick layer of GaInAs (20% In concentration) grown on (001)GaAs does not give any moiré fringes for all low-index Bragg reflections: this result indicates that the effective misfit strain does not correspond to the theoretical one described by the elastic theory. Segregation effects are expected to play an important role in the relaxation of the misfit strain.
Anodic Bond Quality and impact on Pressure Sensor Long-Term Stability
Authors: Allen Henry , Ramzan Kamrul , Knutti Jim , Ross Carl , Milliman Tim , Frye Jeff 
Published: April 2011

ABSTRACTSilicon pressure sensors have historically been fabricating by bonding a glass wafer to a micro-machined silicon wafer. The sensor may be sealed as an absolute pressure sensor by using planar glass and can then be used for detection of barometric pressure changes.It has generally been assumed that as long as the glass and silicon are reasonable clean, then the silicon-glass seal is good and the part becomes a reliable, stable sensor. This paper addresses a low-level drift that was identified in such an absolute pressure sensor. A Zero drift in the range of 0.1% FS was detectable under humidity stresses. The stress always caused drift in the same direction, indicating an effective increased pressure in the sealed cavity.The impact of various cleaning processes in reducing drift are reported. The improved process assure reliable product for applications such as automotive and altimeter applications.
Gettering Control at Bonding Interface in ELTRAN®
Authors: Momoi Kazutaka , Ito Masataka , Sato Nobuhiko , Honma Noriaki , Yonehara Takao 
Published: April 2011

ABSTRUCT:Heavy metal gettering capability on ELTRAN® was studied by controlling surface treatments for handle wafer prior to wafer bonding. Hydrophobic bonding pre-treatments wafer had much higher heavy metal gettering capability at bonding interface than hydrophilic wafer. In the case of hydrophilic bonding pre-treatments, atomically flat bonding interface was observed by cross-sectional TEM. On the other hand, in the case of hydrophobic bonding pre-treatments, “nano gaps” were observed at bonding interface. We concluded that these differences in the structure at the bonding interface caused the difference in the gettering capability. It is possible to control gettering capability by no additional steps in SOI wafer process.
Anomalies in the Behavior of Mo Field Emitter Arrays in Inert Gases and Some Insights into the Degradation Mechanisms
Authors: Reuss Robert H. , Chalamala Babu R. 
Published: April 2011

AbstractField emission displays can be seriously limited by the rapid current degradation of Mo field emitter arrays primarily due to poor vacuum conditions inside their thin vacuum packages. There have been a number of studies to understand the interaction mechanisms. However, we find that models that have been proposed so far are not consistent with observed device behavior in a variety of gas ambients including inert gases and hydrogen. In this paper, we present a summary of our results on residual gases inside a large number of field emission displays, and the effects of these gases on emission behavior. We describe how these issues and the inter-electrode spacing leading to local pressure buildup impact device life. We present an alternate model based on shallow ion implant to explain the observed device behavior.
Study on the Polycrystalline Silicon Films Deposited by Inductively Coupled Plasma Chemical Vapor Deposition
Authors: Moon Byeong Y. , Youn Jae H. , Won Sung H. , Jang Jin , Pietruszko Stanislaw M. 
Published: April 2011

AbstractPolycrystalline silicon thin films have been deposited by an inductively coupled plasma chemical vapor deposition using SiH4/H2 mixtures. The quality of poly-Si can be improved by increasing RF power and hydrogen dilution ratio. The poly-Si deposited at a RF power of 1000 W with an addition of H2, showed a Raman polycrystalline volume fraction of 85.7 %, FWHM of 6.4 cm−1, deposition rate of 9.64 Å/s and SEM grain size of ∼3000 Å.
Relaxed Silicon-Germanium on Insulator (SGOI)
Authors: Cheng Zhiyuan , Currie Matthew T. , Leitz Chris W. , Taraschi Gianni , Lee Minjoo L. , Pitera Arthur , Hoyt Judy L. , Antoniadis Dimitri. A. , Fitzgerald Eugene A. 
Published: April 2011

AbstractWe have fabricated high quality SGOI substrates and demonstrated high mobility enhancement in strained-Si MOSFET's fabricated on the relaxed SGOI substrates with a Ge content of 25%. The substrates were fabricated by wafer bonding. The initial relaxed Si1−xGex layers were grown on Si donor substrates by a graded epitaxial growth technology using ultrahigh vacuum chemical vapor deposition (UHVCVD). The SiGe wafers were then bonded to oxidized silicon handle wafers. Two different approaches have been developed to fabricate SGOI substrates: an etch-back process utilizing a 20% Ge layer as a natural etch stop, and a hydrogen-induced wafer delamination process using H+ implantion. The resultant SiGe film quality was compared among the different approaches. Large-area strained-Si MOSFET's were then fabricated on the SGOI substrates. Epitaxial regrowth was used to produce the upper portion of the relaxed SiGe and the surface strained Si layer. The measured electron mobility shows significant enhancement over both the universal mobility and that of co-processed bulk-Si MOSFET's. This SGOI process has a low thermal budget and thus is compatible with a wide range of Ge contents in Si1−xGex layer.
Enhanced Mobility in 100 nm Strained SiGe Vertical P-MOSFETs Fabricated by UHVCVD
Authors: Jayanarayanan Sankaran , Prins Freek , Chen Xiangdong , Banerjee Sanjay 
Published: April 2011

AbstractStrained SiGe vertical PMOSFETs with a channel length of 100 nm have been fabricated without sophisticated lithography and the whole process is compatible with a regular CMOS process. The source, channel and drain layers with in situ doping were grown by ultrahigh vacuum chemical vapor deposition (UHVCVD) at 500 °C. Atomic force microscopy (AFM) of the SiGe and silicon sample surfaces shows the RMS roughness to be 0.18 nm. X-ray diffraction (XRD) rocking curves of the Si (004) plane demonstrate that the SiGe layers do result in compressive strain. The drive current for the vertical SiGe PMOSFET was enhanced by as much as 80% as compared with the silicon control device, in both the forward and reverse modes of operation.
Future Silicon Nanocrystal Nonvolatile Memory Technology
Authors: Ostraat Michele L. , Blauwe Jan W. De 
Published: April 2011

AbstractA great deal of research interest is being invested in the fabrication and characterization of nanocrystal structures as charge storage memory devices. In these flash memory devices, it is possible to measure threshold voltage shifts due to charge storage of only a few electrons per nanocrystal at room temperature. Although a variety of methods exist to fabricate nanocrystals and to incorporate them into device layers, control over the critical nanocrystal dimensions, tunnel oxide thickness, and interparticle separation and isolation remains difficult to achieve. This control is vital to produce reliable and consistent devices over large wafer areas. To address these control issues, we have developed a novel two-stage ultra clean reactor in which the Si nanocrystals are generated as single crystal, nonagglomerated, spherical aerosol particles from silane decomposition at 950°C at concentrations exceeding 108 cm−3 at sizes below 10 nm. Using existing aerosol instrumentation, it is possible to control the particle size to approximately 10% on diameter. In the second reactor, particles are passivated with a high quality oxide layer with shell thickness controllable from 0.7 to 2.0 nm. The two-stage aerosol reactor is integrated to a 200 mm wafer deposition chamber such that controlled particle densities can be deposited thermophoretically. With nanocrystal deposits of 1013 cm−2, contamination of transition metals and other elements can be controlled to less than 1010 atoms cm−2.We have fabricated 0.2 μm channel length aerosol nanocrystal floating gate memory devices using conventional MOS ULSI processing on 200 mm wafers. The aerosol nanocrystal memory devices exhibit normal transistor characteristics with drive current 30 μA/μm, subthreshold slope 200 mV/dec, and drain induced barrier lowering 100 mV/V, typical values for thick gate dielectric high substrate doped nonvolatile memory devices. Uniform Fowler-Nordheim tunneling is used to program and erase these memory devices. Despite 5 nm tunnel oxides, threshold voltage shifts > 2 V have been achieved with microsecond program and millisecond erase times at moderate operating voltages. The aerosol devices also exhibit excellent endurance cyclability with no window closure observed after 105 cycles. Furthermore, reasonable disturb times and long nonvolatility are obtained, illustrating the inherent advantage of discrete nanocrystal charge storage. No drain disturb was detected even at drain biases of 4V, indicating that little or no charge conduction occurs in the nanocrystal layer. We have demonstrated promise for aerosol nanocrystal memory devices. However, numerous issues exist for the future of nanocrystal devices. These technology issues and challenges will be discussed as directions for future work.
Electrofluidic Assembly of Nanoelectromechanical Systems
Authors: Evoy Stephane , Hailer Ben , Duemling Martin , Martin Benjamin R. , Mallouk Thomas E. , Kratochvilova Irena , Mayer Theresa S. 
Published: April 2011

AbstractRecent advances in surface nanomachining have allowed the fabrication of mechanical structures with dimensions reaching 20 nm, and resonant frequencies in the 100s of MHz. Structural issues prevent the “top-down” surface machining of high-quality NEMS resonators. Such systems are alternatively to be bestowed by “bottom-up” manufacturing technologies. We report the surface assembly of RF-range NEMS. Using electrofluidic assembly, we have successfully positioned Rh mechanical beams onto specific sites of a silicon circuit. With diameters as small as 250 nm and lengths varying from 2 to 3 [.proportional]m, preliminary results show mechanical resonances ranging from 5 MHz to 80 MHz, and quality factors reaching 500. We also report the development of nanostructured NEMS for sensor applications, and present strategies for their deployment in integrative nanosystems.
Surface Micromachined Polysilicon Components Containing Continuous Hinges and Microrivets Used to Realize Three-Dimensional MEMS Structures
Authors: Kolesar Edward S. , Ruff Matthew D. , Odom William E. , Ko Simon Y. , Howard Jeffery T. , Allen Peter B. , Wilks Richard J. , Wilken Josh M. , Bosch Jorge E. , Boydston Noah C. 
Published: April 2011

AbstractA new polysilicon surface micromachining technique for fabricating and assembling three- dimensional structures has been developed. Single-layer polysilicon elements and laminated polysilicon panels incorporating trapped-glass reinforcement ribs have been successfully fabri- cated on a silicon substrate with robust and continuous hinges that facilitate out-of-plane rotation and assembly. To realize a stable three-dimensional structure, one of the device's elevatable panel components is terminated with an array of open windows, and the mating rotatable element has a matched set of protruding arrowheads/microrivets with flexible barbs that readily flex to facilitate their joining and assembly. Because the arrowhead/microrivet barb tip-to-barb tip sepa- ration is larger than the opening in the mating window, the barbs flex inward as they pass through the open window and then expand to their original shape upon exiting the window, re- sulting in a permanently latched joint and a three-dimensional structure. Three novel arrow- head/microrivet designs have been micromachined to facilitate the latching process, including a simple arrowhead, a high-aspect ratio arrowhead, and a rivet-like structure with a hemispherical shaped cap and a flexible split shank.
Fracture Strength of Polysilicon thin Films at Stress Concentrations
Authors: Bagdahn J. , Sharpe W. N. 
Published: April 2011

AbstractThe fracture strengths of 3.5 microns thick and 20 or 50 microns wide polysilicon specimens were measured. One set of specimens was straight in the gage section, another set had a central hole 5.0 microns in diameter, and the third set had symmetric semicircular notches 2.5 microns in radius on each side. The local maximum fracture stresses of the non- uniform specimens, as calculated from the remote fracture stress with a stress concentration factor, were higher than measured in the straight specimens. This indicates a size effect, which is presumably due to the smaller highly stressed volume or area in the non-uniform specimens.
Iron-clad MgB2Superconductor Wires
Authors: Jin S. , Mavoori H. , Bower C. , van Dover R. B. 
Published: April 2011

ABSTRACTThe fabrication of bulk, stoichiometric MgB2wires is a challenge because of the difficulties associated with the volatility and reactivity of magnesium and the brittleness of MgB2. Metal-clad processing of MgB2is a convenient, practical method of overcoming these problems. With such a fabrication approach, iron-clad MgB2superconductor wires exhibiting desirable characteristics with the transport Jcof ∼105 A/cm2at 4.2K have been obtained. In this paper, understanding of the composite wire structures, effect of processing parameters, grain boundary characteristics, and critical current bahavior of the MgB2wires will be described.
Critical Current Properties of Hg(Re)1223 Single Crystals with Various Oxygen Content
Authors: Ueda S. , Shimoyama J. , Sato T. , Horii S. , Otzschi K. , Kishio K. 
Published: April 2011

ABSTRACTHigh quality single crystals of Hg(Re)1223 were grown by the flux method using BaZrO3 crucible, which is stable against molten Ba-Cu-O. The maximum size of the obtained crystal was 1 × 1.1 × 0.1mm3 in dimension. X-ray diffraction analysis revealed that grown crystals are of Hg(Re)1223 single phase with c0 = 15.7 å. In the magnetic hysteresis curves for post-annealed Hg(Re)1223 single crystals under H // c, large second peak effect was found with steep increase of magnetization at approximately 2∼3kOe independent of temperature. The peak field systematically increased with a decrease of temperature, suggesting generation of field-induced pinning. Critical current density and irreversibility field of single crystals were dependent on synthesis batch, possibly due to the difference in resulting concentration of Re, while postannealing under various conditions did not affect largely for critical current properties. Irreversibility lines of the Hg(Re)1223 single crystals locate at higher fields than that of Re-free Hg1223. This suggests that electromagnetic anisotropy is reduced by Re-doping, which is consistent with the recent results on the resistive anisotropy in the normal state.
The Nature of Surface Oxides on Magnesium Diboride
Authors: Meegoda Chandana , Paderno Yu. , Trenary Michael 
Published: April 2011

ABSTRACTSurface oxides present on polycrystalline MgB2 were characterized by high-resolution x-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES). X-ray diffraction (XRD) measurements were used to determine the MgB2 phases. XRD line broadening analysis reveals a grain size of 40 nm. XPS results show that MgO and B2O3 are the major surface oxides. Auger spectra provide further evidence of the presence of MgO. The B 1s and Mg 2p peaks have been used to quantify the amount of the surface oxides.
Overview of U.S. Department of Energy Superconductivity Program for Electric Power
Authors: Hawsey Robert A. 
Published: April 2011

ABSTRACTA top priority of the U.S. government is to improve the energy delivery infrastructure. According to the report issued May 2001 by the National Energy Policy Development (NEPD) Group, “For the electricity we need, we must be ambitious. Transmission grids stand in need of repair, upgrading, and expansion…if we put these connections in place, we'll go a long way to avoiding future blackouts.” Superconductivity is such an important aspect of our nation's energy future that we should “…expand the Department's research and development on transmission reliability and superconductivity.” Prototype superconducting power cables that will help upgrade our power grid when commercialized later this decade are being demonstrated today in Carrollton, Georgia and Detroit, Michigan. Much research remains, however, if the superconducting wires are to have the electrical performance and low-cost features necessary for U.S. companies to fully commercialize new transmission cables that will help eliminate the bottlenecks in urban areas. The U.S. Department of Energy (DOE) leads the U.S. national effort to develop high-temperature superconducting (HTS) wires and to demonstrate prototype electric power applications using the best wires available today. The industry-led Second Generation Wire Initiative is exploiting breakthroughs at the national laboratories that promise unprecedented current carrying capacity in HTS wires at lower cost than first-generation “BSCCO” wires. Some of the recent progress in the U.S. development of HTS “coated conductors” and in fielding prototype applications is presented
Thermomechanical Characterization of Bismuth Telluride Based Thermoelectric Materials
Authors: Brostow Witold , Menard Kevin P. , White John B. 
Published: April 2011

ABSTRACTThe thermoelectric properties of bismuth telluride based thermoelectric (TE) materials are well-characterized, but comparatively little has been published on the mechanical and thermomechanical properties of these materials. In this paper, we present the initial dynamic mechanical analysis (DMA) data for n-type and p-type bismuth telluride based TE materials. The materials' tan δ values, indicative of viscoelastic energy dissipation modes, approach that of glassy or crystalline polymers and are greater than ten times the tan delta of structural metals. TE samples measured perpendicular to the van der Waals planes have higher tan δ values. Thermal scans in the DMA compressive mode showed changes in mechanical properties versus temperature with clear hysteresis effects. These changes were correlated to differential scanning calorimetry (DSC) thermal transitions. The expected anisotropy was shown in flexural 3-point bending results for one n-type material that showed a storage modulus of 0.10 to 0.45 GPa in the direction parallel to the van der Waals planes and 0.07 to 0.2 GPa in the perpendicular direction.
Nuclear Density Analysis in Solids. The Case of Ba8Ga16Si30
Authors: Iversen B. B. , Bentien A. , Palmqvist A. E. C. , Bryan D. , Stucky G. D. , Schultz A. J. , Henning R. W. 
Published: April 2011

ABSTRACTMulti-temperature (15, 100, 150, 200, 300, 450, 600, 900 K) single crystal neutron diffraction data on the type I clathrate Ba8Ga16Si30are analyzed with the maximum entropy method to obtain direct space nuclear densities. The nuclear densities suggest that the guest atoms are structurally disordered, and the disorder appears to be temperature dependent with increased host-guest interaction at high temperatures.