bluuebunny/crossref_metadata_2025_split huggingface dataset:
Growth of hydrogenated microcrystalline silicon (μc-Si:H) films by HWCVD using a Graphite catalyzer
Authors: Bhusari D.M. , Kumar P. , Kupich M. , Schroeder B. 
Published: April 2011

ABSTRACTA graphite catalyzer has been used to grow μc-Si:H films using the thermo-catalytic (HW) chemical vapor deposition (CVD) technique. The films grown in the amorphous-microcrystalline ‘transition regime’ have been found to exhibit a high photosensitivity of the order of 102-103 at a crystalline volume fraction of 0.2-0.4. The effects of deposition parameters such as silane concentration, pressure and substrate temperature on the microstructure and electrical properties of the films have been studied. It has been found that the graphite catalyzer offers a wider window of the deposition parameters for the growth of the ‘transition regime’ films as compared to the conventional W and Ta catalyzers. In addition, the graphite wires also exhibit significantly greater chemical as well as mechanical stability than the W and Ta wires, which results in improvement of the reproducibility of the technique. However, at the same filament temperature and other conditions, the deposition rates are about 10 times lower than for W or Ta filament. Increasing of the filament temperature, on the contrary, lead to radiative heating and carbon contamination of the growing film.
Devices Fabrication with Narrow-Bandgap a-SiGe:H Alloys Deposited by HWCVD
Authors: Xu Yueqin , Yan Baojie , Nelson Brent P. , Iwaniczko Eugene , Reedy Robert C. , Mahan A.H. , Branz Howard 
Published: April 2011

ABSTRACTWe incorporate narrow-gap amorphous silicon germanium (a-SiGe:H) alloys grown by hot-wire chemical vapor deposition (HWCVD) into single-junction n-i-p solar cells, and improve both fill factor (FF) and open-circuit voltage (Voc) by bandgap grading. The Tauc bandgap (ET) of the a-SiGe:H is as low as about 1.25 eV. Previously [1], we obtained a short-circuit current density (Jsc) up to 20 mA/cm2 in an n-i-p device incorporating an ungraded 120-nm i-layer of 1.25-eV a-SiGe:H. However, without buffer layers or bandgap profiling, the fill factor was only 38%, likely due to an abrupt bandgap transition and poor hole collection. To overcome these problems, we have used composition bandgap profiling throughout the i-layer and improved both Voc and FF significantly without any Jsc loss. The solar cell efficiency is improved from 3.55% to 5.85% and Voc rises from 0.475 to 0.550 eV. This improved single-junction a-SiGe:H solar cell has a quantum efficiency of about 48% at l=800 nm and about 15% at l=900 nm. We present details of the bandgap profiling and its effect on device performance.
Channel engineering and junction overlap issues for ultra-shallow junctions formed by SPER in the 45 nm CMOS technology node
Authors: Severi Simone , Henson Kirklen , Lindsay Richard , Lauwers Anne , Pawlak Bartek J. , Surdeanu Radu , Meyer K. De 
Published: April 2011

ABSTRACTThe feasibility of the SPER junction process as a reasonable alternative to the spike anneal junction is proved in this work. Good control of the SCE and performance competitive results as compared to the spike junction are obtained. An analysis of the interaction between the halo dopant and the SPER junctions has been carried out; it is shown that the performance degrades with increasing halo dose as a consequence of an overlap resistance problem.
Simulation and Electron Energy-Loss Spectroscopy of Electron Beam Induced Point Defect Agglomerations in Silicon
Authors: Stoddard Nathan G. , Duscher Gerd , Windl Wolfgang , Rozgonyi George A. 
Published: April 2011

ABSTRACTNitrogen doped silicon samples were irradiated with 200 kV electrons in a transmission electron microscope (TEM). The resulting room temperature point defect creation, bonding and segregation were studied by in situ conventional and Z Contrast TEM imaging and electron energy loss spectroscopy (EELS). Energy loss spectra from areas attributed to be rich in vacancies or silicon self-interstitials are found to be significantly different from the bulk in the near-edge structure of their Si-L2,3 edges. The experimental results are compared with ab initio density of states calculations for electronically excited atoms near relaxed point defect structures and plans are outlined to extend this technique to individual point defect characterization.
Study of Ni(Pt) germanosilicides formation on fully-strained Si0.9Ge0.1 and Si0.899Ge0.1C0.001 by Raman Spectroscopy
Authors: Chaw J. Y. Y. , Pey K. L. , Lee P. S. , Chi D. Z. , Liu J. P. 
Published: April 2011

ABSTRACTIn this work, Raman spectroscopy was used to study the reaction of pure Ni and Ni(Pt 5 at. %) with fully-strained Si0.9Ge0.1 and Si0.899Ge0.1C0.001. With pure Ni, it was found that the incorporation of 0.1% C in the substrate resulted in out-diffusion of Ge from the germanosilicide film at a lower rapid thermal annealing (RTA) temperature compared to that of pure Ni on Si0.9Ge0.1. This Ge out-diffusion phenomenon is evident from the gradual shift in the NiSi1-wGew (w ≤ x) Raman peak from ∼213 cm−1 to higher wavenumbers, closer to 217 cm−1 as reported for pure Ni/Si, indicating that Ge is being depleted from the film with increasing RTA temperatures. In addition, it was found that severe agglomeration of the germanosilicide film occurred at a lower RTA temperature for the Ni/Si0.899Ge0.1C0.001 system. This corresponds to the observations from the Raman spectra, where a sharp increase in the Si substrate peak at 520 cm−1 was observed, coupled with the appearance of the transverse acoustic (TA)-phonon peak of Si at 301 cm−1. When Pt was introduced into the Ni film, significant improvements were observed for the germanosilicide films on Si0.9Ge0.1 and Si0.899Ge0.1C0.001 substrates, both in terms of Ge out- diffusion and agglomeration. Initial findings show that the addition of Pt promotes the formation of the low resistivity mono-germanosilicide phase at temperatures as low as 300°C.
Millisecond Microwave Annealing: Reaching the 32 Nm Node
Authors: Thompson Keith , Booske John H. , Ives R.L. , Lohr John , Gorelov Yurii A. , Kajiwara Ken 
Published: April 2011

ABSTRACTThe next generation of Si devices requires thermal treatments of 1200°C – 1300°C but can only withstand temperatures above 800°C for a few milliseconds. Current rapid thermal processing techniques cannot meet these requirements. We have designed, constructed, and tested a microwave reactor that heats Si to 1300°C in only a few milliseconds and cools the wafer at a rate that exceeds a million degrees per second. Applying millisecond microwave annealing to ultra-shallow junction formation in advanced Si devices shows that this technique meets or exceeds the thermal processing requirements for the next several generations of Si devices.
Boron-Interstitial Cluster Kinetics: Extraction of Binding Energies from Dedicated Experiments
Authors: Ortiz Christophe J. , Pichler Peter , Häaublein Volker , Mannino Giovanni , Scalese Silvia , Privitera Vittorio , Solmi Sandro , Lerch Wilfried 
Published: April 2011

ABSTRACTA description of the transient diffusion and activation of boron during post-implantation an- nealing steps is one of the most challenging tasks. In industrially relevant situation, it needs to address diffusion at extrinsic concentrations, the agglomeration of self-interstitials, and the formation of boron-interstitial clusters. This article describes the experimental work performed or used to calibrate model parameters as independently as possible. In particular, the experiments used to extract information about the energetics of boron-interstitial clusters are described.
Free-standing line patterns of nanocrystalline electrodeposits
Authors: Pantleon Karen , Jensen Henrik Myhre , Somers Marcel A.J. 
Published: April 2011

AbstractFree-standing Cu- and Ni-line patterns with varying line dimensions in the range of a few micrometers were manufactured by means of electrodeposition through a lithographically prepared mask. XRD studies revealed for Cu-lines a pronounced influence of the pattern geometry on crystallographic texture and peak broadening. Information on the strain distribution within individual Cu-lines was obtained from FEM.
Pulsed MOCVD of Cu Seed Layer using a (Hfac)Cu(3,3-Dimethyl-1-Butene) Source Plus H2 Reactant
Authors: Park Jaebum , Yang Heejung , Lee Jaegab 
Published: April 2011

AbstractPulsed metalorganic chemical vapor deposition (MOCVD) of conformal copper seed layers, for the electrodeposition Cu films, has been achieved by an alternating supply of a Cu(I) source and H2 reactant at the deposition temperatures of 50 - 100°C. The Cu thickness increased proportionally to the number of cycle, and the growth rate was in the range of 3.5 to 8.2 A /cycle, showing the ability to control the nano-scale thickness. As-deposited films show highly smooth surfaces even for more than 100nm. In addition, about a 90% step coverage was obtained inside trenches, with an aspect ratio greater than 30:1. H2, introduced as a reactant gas, can play an active role in achieving highly conformal coatings, with increased grain sizes.
Adhesion Strength Evaluation of Low-k Interconnect Structures Using a Nanoscratch Method
Authors: Ye Jiping , Ueoka Kenichi , Kojima Nobuo , Shimanuki Junichi , Shimada Miyoko , Ogawa Shinichi 
Published: April 2011

AbstractA convenient nanoscratch method was combined with atomic force microscope (AFM) and transmission electron microscope (TEM) observations to conduct the first-ever evaluation of the adhesion strength of a complicated microstructure Cu/Ta/TaN/pSiO2/low-k/SiC/pSiO2/Si-substrate with the aim of correlating the fracture strength with the results of chemical mechanical polishing (CMP) tests. Concretely, this evaluation focused on the fact that specimens having a low-k layer pretreated with rare-gas plasma prior to the deposition of the SiO2 layer exhibited low delaminated densities in the Cu CMP process. It was found that a specimen with the rare-gas plasma pretreatment exhibited a higher friction coefficient, a higher critical load and brittle adhesive failure resulting from delamination at the interface between the low-k and SiC layers. A specimen without the rare-gas plasma pretreatment displayed a lower friction coefficient, a lower critical load, and ductile cohesive failure in the low-k layer. Because less plastic deformation was observed in the low-k layer subjected to the rare-gas plasma pretreatment, it is assumed that the pretreatment reinforced the mechanical properties of the low-k layer, making it more resistant to ductile cohesive failure. These results agreed with the CMP test data and indicated that the nanoscratch method makes it possible to predict the ability of complicated Cu/low-k interconnect structures to withstand the CMP process.
Anisotropic Elastic Properties of Low-k Dielectric Materials
Authors: Maznev A.A. , Mazurenko A. , Alper G. , Moore C.J.L. , Gostein M. , Schulberg Michelle T. , Humayun Raashina , Sengupta Archita , Sun Jia-Ning 
Published: April 2011

AbstractA non-contact optical technique based on laser-generated surface acoustic waves (SAWs) was used to characterize elastic properties of two types of thin (150-1100 nm) low-k films: more traditional non-porous organosilicate glass PECVD films (k=3.0) and novel mesoporous silica films fabricated in supercritical CO2 (k=2.2). The acoustic response of the non-porous samples is well described by a model of an elastically isotropic material with two elastic constants, Young's modulus and Poisson's ratio. Both parameters can be determined by analyzing SAW dispersion curves. However, the isotropic model fails to describe the SAW dispersion in the mesoporous samples. Modifying the model to allow a difference between in-plane and out-of plane properties (i.e., a transversely isotropic material) results in good agreement between the measurements and the model. The in-plane compressional modulus is found to be 2-3 times larger than the out-of plane modulus, possibly due to the anisotropic shape of the pores. Elastic anisotropy should therefore be taken into account in modeling mechanical behavior of low-k materials.
Evaluation of Thin Dielectric-Glue Wafer-Bonding for Three Dimensional Integrated Circuit-Applications
Authors: Kwon Y. , Yu J. , McMahon J.J. , Lu J.-Q. , Cale T.S. , Gutmann R.J. 
Published: April 2011

AbstractThe critical adhesion energy of benzocyclobutene (BCB)-bonded wafers is quantitatively investigated with focus on BCB thickness, material stack and thermal cycling. The critical adhesion energy depends linearly on BCB thickness, increasing from 19 J/m2 to 31 J/m2 as the BCB thickness increases from 0.4 μm to 2.6 μm, when bonding silicon wafers coated with plasma enhanced chemical vapor deposited (PECVD) silicon dioxide (SiO2). In thermal cycling performed with 350 and 400 oC peak temperatures, the significant increase in critical adhesion energy at the interface between BCB and PECVD SiO2 during the first thermal cycle is attributed to relaxation of residual stress in the PECVD SiO2 layer. On the other hand, the critical adhesion energy at the interface between BCB and PECVD silicon nitride (SiNx) decreases due to the increase of residual stress in the PECVD SiNx layer during the first thermal cycle.
Hydrogen in Ultralow Temperature SiO2for Nanocrystalline Silicon Thin Film Transistors
Authors: Kattamis Alex , Cheng I-Chun , Allen Steve , Wagner Sigurd 
Published: April 2011

AbstractNanocrystalline silicon is a candidate material for fabricating thin film transistors with high carrier mobilities on plastic substrates. A major issue in the processing of nanocrystalline silicon thin film transistors (nc-Si:H TFTs) at ultralow temperatures is the quality of the SiO2gate dielectric. SiO2deposited at less than 250°C by radio frequency plasma enhanced chemical vapor deposition (rf-PECVD), and not annealed at high temperature after deposition, exhibits high leakage current and voltage shifts when incorporated into TFT's. Secondary ion mass spectrometry (SIMS) measurements show that the hydrogen concentration (NH) in PECVD oxide deposited at 150°C on crystalline silicon (x-Si) is ∼ 0.8 at. %. This is much higher than in thermal oxides on x-Si, which display concentrations of less than 0.003 at. %. The leakage current density for thermal oxides on x-Si at a bias of 10 V is ∼9×10−6A/cm2whereas for 200°C PECVD oxides on nc-Si:H the current is ∼1×10−4A/cm2. As the temperature of the SiO2deposition is reduced to 150°C the current density rises by up to two orders of magnitude more. The H which is suspected to cause the leakage current across the PECVD oxide originates from the nc-Si:H substrate and the SiH4source gas. We analyzed the 300-nm gate oxide in capacitor structures of Al / SiO2/n+nc-Si:H / Cr / glass, Al / SiO2/ n+nc-Si:H / x-Si, and Al / SiO2/ x-Si. Vacuum annealing the nc-Si:H prior to PECVD of the oxide drives H out of the nc-Si:H film and reduces the amount of H incorporated into the oxide that is deposited on top. SiO2film deposition from SiH4and N2O at high He dilution has a still greater effect on lowering NH. The leakage current at a 10 V bias dropped from ∼1×10−4A/cm2to about ∼2×10−6A/cm2using He dilution at 250°C, and the vacuum anneal of the nc-Si:H lowered it by an additional factor of two. Thus we observe that both the nc-Si:H anneal and the SiO2deposition at high He dilution lessen the gate leakage current.
Recent Advances in the Synthesis of Polyfluorenes as Organic Semiconductors
Authors: Brennan David J. , Chen Yu , Feng Shaoguang , Godschalx James P. , Spilman Gary E. , Townsend Paul H. , Kisting Scott R. , Dibbs Mitchell G. , Shaw Jeff M. , Welsh Dean M. , Miklovich Jessica L. , Stutts Debra 
Published: April 2011

AbstractNew poly(fluorene-thiophene) alternating copolymers are described in which either the dioctylfluorene or bithiophene units in poly(9,9-dioctylfluorene-alt-bithiophene) (F8T2) are replaced by other fluorene or thiophene-based groups, respectively. Improvements in solubility are realized when the bithiophene unit of F8T2 is replaced by dihexylterthiophene or dihexylpentathiophene units. Melting temperatures are also lowered by 50 – 100°C in these polymers when compared to F8T2. Replacement of the bithiophene unit of F8T2 with a dihexylpentathiophene unit also results in a significant improvement in hysteresis (< 2 V vs. 3.5 – 5 V for F8T2). Initial results are also reported on the thermal cleavage of the C8side groups of F8T2, which yields an insoluble polymeric semiconductor film that continues to exhibit transistor switching characteristics as part of a bottom gate device.
Crystalline Organic Semiconducting Thin Films Cast from a Novel Thermolytic Thiophene Oligomer
Authors: Chang Paul C. , Murphy Amanda R. , Lee Josephine B. , Fréchet Jean M. J. , Subramanian Vivek 
Published: April 2011

AbstractHere we report on OTFTs made from a novel thermoresponsive thiophene based oligomer. The functionalized oligomer is soluble in common solvents, but loses its solubility upon thermolysis. Devices with channel lengths from 5 to 40 νm were fabricated from solution then subjected to thermolysis at temperatures ranging from 150-250°C. The initially amorphous materials reorganize into highly crystalline films upon thermolysis. Crystallinity was characterized by x-ray diffractometry and atomic force imaging. AFM studies depicted the nucleation of molecular terraces, where the formation and overall height of terraces was observed to be dependent upon the thermolysis temperature and solvent choice. These factors correlated to overall performance. For both dip-cast and spin-cast samples, devices were fabricated at a process temperature of 180°C with mobilities of 0.07 cm2/Vs and on/off ratios > 105. The deves were relatively stable in both air and common solvents, with their mobility degrading only by ∼25% upon immersion in the original casting solvents. The solubility characteristics and process temperatures for these devices may be particularly suitable for solution processing on flexible substrates.
Two causes of source/drain series resistance in bottom-contact pentacene thin-film transistors
Authors: Noda Makoto , Yoneya Nobuhide , Hirai Nobukazu , Kawashima Noriyuki , Nomoto Kazumasa , Wada Masaru , Kasahara Jiro 
Published: April 2011

AbstractWe identified two causes of source/drain (S/D) series resistance (Rs) in bottom-contact (BC) pentancene thin-film transistors (TFTs). One is mixed-phase pentacene grown in the blurred- edge region of Au electrodes and the other is the semi-insulating pentacene region between the Au electrode and the carrier-accumulating layer. A novel Au S/D electrode structure with a self-assembled monolayer (SAM) adhesion layer enables direct injection of carriers into the accumulating layer and markedly reduces Rs for unit gate width (RsW) to 6 Mωμ[.proportional]m. BC TFTs with this electrode structure showed extrinsic field-effect mobility as high as 1.1 cm2/Vs.
Study of Percolation in PMMA / Indium Tin Oxide Composites
Authors: Capozzi Charles J. , Shackelford Sandra , Ou Runqing , Gerhardt Rosario A. 
Published: April 2011

AbstractKnowledge of percolation in binary composites is critical to the development of new materials with specific electrical and optical properties. This report investigates the detection of percolation in novel two-phase composites consisting of poly(methyl) methacrylate(PMMA) and indium tin oxide (ITO). ITO is a filler of particular interest primarily for possessing optical clarity consistent with PMMA in the visible light range. AC impedance measurements were performed on specimens with varying concentrations of ITO particles to determine the percolation threshold. Percolation was observed when specimens contained 2-3% vol. of nano- sized ITO and 6%-8% vol. of coarse-sized ITO. Thus, the percolation threshold appeared significantly decreased with reduced particle size of the filler. It is speculated that minor agglomerates in the bulk of the specimens may have prevented percolation from occurring at even lower volume fractions of the filler phase.
Nanocrystalline fcc metals: bridging experiments with simulations
Authors: Swygenhoven H. Van , Derlet P. M. , Frøseth A. G. , Petegem S. Van , Budrovic Z. , Hasnaoui A. 
Published: April 2011

AbstractAtomistic simulations have provided unprecedented insight into the structural and mechanical properties of nanocrystalline materials, highlighting the role of the non-equilibrium grain boundary structure in both inter- and intra-grains deformation processes. One of the most important results is the capability of the nanosized grain boundary to act as a source and sink for dislocations. However the extrapolation of this knowledge to the experimental regime requires a clear understanding of the temporal and spatial scales of the modelling technique and a detailed structural characterisation of the simulated samples. In this contribution some of the synergies that can be develo ped between atomistic simulations and experiments for this research field are briefly discussed by means of some typical examples.
Twin Boundaries and Stacking Faults in Monazite (Monoclinic
LaPO4)
Authors: Hay Randall S. 
Published: April 2011

AbstractMonazite (LaPO4) was indented at room temperature. Deformation twin
boundaries and stacking faults were characterized by high resolution transmission
electron microscopy. Kinked deformation twins were also characterized and analyzed.
Three types of stacking faults associated with climb-dissociated partial dislocations
were observed. Two were found on twin boundaries, and a third in the lattice.
Formation mechanisms are discussed. The superimposition of stacking faults along twin
boundaries during deformation twinning and the glide of climb-dissociated partial
dislocations allowed by stacking fault migration are discussed. The possible
relationship between the formation mechanisms for these defects and the low-
temperature recrystallization and self-annealing of defects in monazite is
considered.
Quantum-Dot Molecules for Potential Applications in Terahertz Devices
Authors: Stoleru Valeria Gabriela , Towe Elias , Ni Chaoying , Pal Debdas 
Published: April 2011

ABSTRACTThe experimental and theoretical results of the electronic and optical properties of quantum dot artificial molecules (AMs), formed by pairs of electronically coupled quantum dots (QDs), are presented here in order to identify the necessary conditions for the development of new types of terahertz (THz) injection lasers based on intraband carrier transitions. We have performed analytical calculations to obtain the spatial strain distribution in vertically aligned (In, Ga)As QDs grown on (001) GaAs substrates by molecular beam epitaxy. Electronic coupling of the dots, mainly governed by the thickness of the separating barrier between the dot layers, is allowed due to the strain field-assisted self-organization of the dots. The calculated strain field reproduces our cross sectional high-resolution transmission electron microscopy observations very well. We further take into account the microscopic effects of the spatial strain distribution on carrier confinement potentials, and compute the electronic structure of the AM. Our calculations of the peak luminescence energies are in good agreement with our experimental results and those of others. The growth of quantum dot molecules represents a major step in tailoring the electronic and optical properties of the nanostructures.