bluuebunny/crossref_metadata_2025_split huggingface dataset:
Conductance Transients Study of Slow Traps in Al/SiNx:H/Si and Al/SiNx:H/InP Metal-Insulator-Semiconductor Structures
Authors: Dueñas S. , Peláez R. , Castán E. , Barbolla J. , Mártil I. , Gonzalez-Diaz G. 
Published: April 2011

ABSTRACTWe have obtained Al/SiNx:H/Si and Al/SiNx:H/InP Metal-Insulator-Semiconductor devices by directly depositing silicon nitride thin films on silicon and indium phosphide wafers by the Electron Cyclotron Resonance Plasma method at 200°C. The electrical properties of the structures were first analyzed by Capacitance-Voltage measurements and Deep-Level Transient Spectroscopy (DLTS). Some discrepancies in the absolute value of the interface trap densities were found. Later on, Admittance measurements were carried out and room and low temperature conductance transients in the silicon nitride/semiconductor interfaces were found. The shape of the conductance transients varied with the frequency and temperature at which they were obtained. This behavior, as well as the previously mentioned discrepancies, are explained in terms of a disorder-induced gap-state continuum model for the interfacial defects. A perfect agreement between experiment and theory is obtained proving the validity of the model.
X-Ray Absorption Spectroscopy as an in-situ Tool in Materials Science
Authors: Ressler T. , Wong Joe , Metz W. 
Published: April 2011

ABSTRACTIn addition to being an established technique for ex-situ structural studies, x-ray absorption spectroscopy (XAS) has recently been realized to be a powerful tool for in-situ time-resolved investigations in materials science. This paper describes two complementary techniques: quick-scanning EXAFS (QEXAFS) and energy-dispersive XAS (DXAS) which offer time resolution in the seconds and milliseconds range, respectively. Formation of a heterogeneous catalyst from a solid-state reaction of a precursor is presented as an example of a time-resolved XAS application.
Effect of Current Distribution on Quartz Crystal Microbalance Measurements
Authors: Kelly James J. , Durning Christopher J. , West Alan C. 
Published: April 2011

ABSTRACTSpatially nonuniform electrodeposition can cause discrepancies between predicted and experimentally measured mass loadings on an electrochemical quartz crystal microbalance (EQCM) since the sensitivity of the quartz crystal varies significantly from point to point. These discrepancies can be significant even if the current distribution is nearly uniform. These effects were examined experimentally by varying the conductivity of the electrolyte and the current density during the electrodeposition of copper on an EQCM, effecting changes in the spatial, deposited-mass distribution in a controlled manner. The resulting frequency shifts are in agreement with results predicted by current distribution simulations, validated a posteriori with profilometry measurements. Our results permit determination of the spatial variation of the quartz crystal sensitivity factor or of the current distribution on the EQCM.
In-Situ Monitoring during PLD of Complex Oxides using Rheed at High Oxygen Pressure
Authors: Rijnders Guus J. H. M. , Koster Gertian , Blank Dave H. A. , Rogalla Horst 
Published: April 2011

ABSTRACTSeveral groups have monitored the growth of complex oxides in-situ using Reflection High Energy Electron Diffraction (RHEED). In order to utilize RHEED during growth, films are deposited at low background oxygen pressures. Because of the low oxidation power at low pressures, low substrate temperatures have to be used. This hampers, in general, the film crystallinity. Furthermore, the background pressure in Pulsed Laser Deposition (PLD) is an important parameter, because it influences the shape and size of the plasma and, therefore, the deposition rate and homogeneity of the film.We have developed a high-pressure RHEED system, which can be used for growth monitoring during the deposition of complex oxides at standard PLD conditions. Clear diffraction patterns are observable up to 50 Pa, due to the minimized scattering losses.SrTi03 substrate treatments as well as growth studies of Yba2Cu3O7−δ, using atomic layers of SrO or BaO as a buffer-layer, will be discussed in this contribution. It will be shown that monitoring and control of thin film growth by PLD on an atomic level is feasible, even in quite high background pressures.
In Situ Fhir Spectroscopic Detection of Adsorbed Species on Sapphire Substrates in a Diamond ECR-Pacvd System
Authors: Shahedipour F. , Zhu S. , White H. W. 
Published: April 2011

ABSTRACTIn situ Fourier Transform Infrared Reflection Absorption Spectroscopy (FTIRRAS) has been used to study the adsorbed plasma species on sapphire substrate throughout the nucleation and deposition stages under diamond deposition conditions. The focus of this work has been on one of the most fundamental questions in the area of diamond film synthesis that concerns the gas species (precursors) responsible for diamond nucleation and growth especially on foreign substrates. It is experimentally shown here that the most probable precursor for diamond nucleation in methane-hydrogen plasma are methyl radicals.Diamond deposition on randomly oriented sapphire substrates has been successfully achieved under low pressure- low temperature deposition conditions using an electron cyclotron resonance microwave plasma assisted chemical vapor deposition (ECR-PACVD) system. The deposited thin films were characterized by Raman spectroscopy, and scanning electron microscopy.
Spectroscopic Determination of C2 Densities in AR/H 2/CH 4 and AR/H2/C60 Microwave Plasmas For Nanocrystalline Diamond Synthesis
Authors: Goyette A. N. , Lawler J. E. , Anderson L. W. , Gruen D. M. , Mccauley T. G. , Zhou D. , Krauss A. R. 
Published: April 2011

ABSTRACTWe have measured the steady state concentration of gas phase C2 in Ar/H2/CH4 and Ar/H2/C60 microwave plasmas used for the deposition of nanocrystalline diamond films. High sensitivity white light absorption spectroscopy is used to monitor the C2 density using the d 3 Π ← a3Π (0,0) vibrational band of C2 as chamber pressure, microwave power, substrate temperature and feed gas mixtures are varied in both chemistries. Understanding how these parameters influence the C2 density in the plasma volume provides insight into discharge mechanisms relevant to the deposition of nanocrystalline diamond.
CVD Growth and Excimer Laser Processing of SiGe Alloys Monitored by Single Wavelength Ellipsometry and Atomic Force Microscopy
Authors: Larciprete R. , Padeletti G. , Cozzi S. , Pieretti S. 
Published: April 2011

ABSTRACTSingle wavelength ellipsometry was used to monitor the CVD growth of Si(1-x)Gex alloys onSi and to evaluate the effect of sample irradiation by KrF laser pulses, performed during or afterthe CVD growth. The information obtained was correlated with AFM analysis results in order tooptimize the growth parameters for an improved morphological quality of the alloy layers.
Closed-Loop Control of MBE Using an Integrated Multi-Sensor System
Authors: Roth John A. 
Published: April 2011

ABSTRACTThe use of in situ sensors to achieve real-time control of molecular beam epitaxy (MBE) is a rapidly evolving technology that promises to revolutionize MBE in terms of process repeatability and first-pass success, and consequently to improve the overall yield and reduce the cost of the process. To achieve robust real-time control of MBE, we have constructed a multiple-sensor control system comprising in situ sensors for substrate temperature, for effusion cell fluxes, and for the epitaxial layer composition and thickness, along with advanced software to manage the sensor information and execute sensor-feedback control algorithms. This system has been used to grow a number of different III-V semiconductor materials and device structures, including heterojunction bipolar transistors, resonant tunneling devices, and mid-IR lasers. In the present paper, we present results demonstrating control and regulation of substrate temperature and epitaxial layer composition during the growth of lattice-matched InGaAs and InA1As on InP. The control algorithms and software used in the system are described, and we discuss how the synergistic application of multiple sensors allows the regime of composition control to be expanded beyond what would be possible with only a single composition sensor.
Nanoindentation of Soft Films On Hard Substrates: Experiments And Finite Element Simulations
Authors: Pharr G. M. , Bolshakov A. , Tsui T. Y. , Hay Jack C. 
Published: April 2011

ABSTRACTExperiments and finite element simulations have been performed to examine errors in the measurement of hardness and elastic modulus caused by pile-up when soft films deposited on hard substrates are tested by nanoindentation methods. Pile-up is exacerbated in soft-film/hardsubstrate systems by the constraint imposed on plastic deformation in the film by the relatively non-deformable substrate. To experimentally examine pile-up effects, soft aluminum films with thicknesses of240, 650, and 1700 nm were deposited on hard soda-lime glass substrates and tested by nanoindentation techniques. This system is attractive because the elastic modulus of the film and the substrate are approximately the same, but the substrate is harder than the film by a factor of about ten. Consequently, substrate influences on the indentation load-displacement behavior are manifested primarily by differences in the plastic flow characteristics alone. The elastic modulus of the film/substrate system, as measured by nanoindentation techniques, exhibits an increase with indenter penetration depth which peaks at a value approximately 30% greater than the true film modulus at a penetration depth close to the film thickness. Finite element simulation shows that this unusual behavior is caused by substrate-induced enhancement of pile-up. Finite element simulation also shows that the amount of pile-up increases with increasing penetration depth, and that the pile-up geometry depends on the work-hardening characteristics of the film. Because of these effects, nanoindentation techniques overestimate the true film hardness and elastic modulus by as much as 68% and 35%, respectively, depending on the work-hardening behavior of the film and the indenter penetration depth. The largest errors occur in non-work-hardening materials at penetration depths close to the film thickness, for which substrate-induced enhancement of pile-up is greatest.
Full Field Measurements of Curvature using Coherent Gradient Sensing: Application to Thin Film Characterization
Authors: Rosakis A. J. , Singh R. P. , Tsuji Y. , Kolawa E. , Moore N. R. 
Published: April 2011

ABSTRACTThis paper introduces coherent gradient sensing (CGS) as an optical, full-field, real-time, non-intrusive and non-contact technique for measurement of curvature and curvature changes in thin film and micro-mechanical structures. The technique is applied to determine components of the curvature tensor field in multilayered thin films deposited on silicon wafers. Curvature field measurements using CGS are compared with average curvatures obtained using high-resolution x-ray diffraction. Finally, examples are presented to demonstrate the capability of CGS in measuring curvature in a variety of thin film and micro-mechanical structures.
Strain Relaxation in Iv-vi Semiconductor Layers Grown on Silicon (100) Substrates
Authors: Sachar H. K. , McCann P. J. , Fang X. M. 
Published: April 2011

ABSTRACTThe large thermal expansion coefficient mismatch between IV–VI semiconductors and silicon results in significant tensile strain when structures are cooled down following growth at high temperatures. Molecular beam epitaxy (MBE) growth of PbSe on Si (100) at 280°C on BaF2/CaF2 buffer layers results in high crack-density because of this strain. Interestingly, crack- free layers of PbSe can be grown by LPE on Si (100) by using MBE-grown PbSe/BaF2/CaF2 buffer layer structures. Unlike LPE-grown PbSe layers, however, a high crack-density was observed in Pbl-xSnxSe1-yTey layers grown by LPE on Si (100) using similar buffer layer structures. It is hypothesized that the addition of tellurium, which is known to increase IV-VI material hardness, inhibits plastic deformation and thus crack formation becomes the thermal strain relief mechanism. Ternary Pbl-xSnxSe layers grown by LPE exhibited much lower crack densities as compared to the quaternary layers and supported the conclusion that tellurium induced solid solution hardening occurs in the IV-VI materials system.
Interfacial Stability and Misfit Dislocation Formation in InAs/Gaas(110) Heteroepitaxy
Authors: Zepeda-Ruiz Luis A. , Maroudas Dimitrios , Weinberg W. Henry 
Published: April 2011

ABSTRACTA comprehensive atomic-scale study is presented of the mechanical behavior of the InAs epitaxial film, the interfacial stability with respect to misfit dislocation formation, and the film surface morphology in InAs/GaAs(110) heteroepitaxy. If a GaAs buffer layer of ten-monolayer thickness is used in the epitaxial growth, a transition is predicted from a coherent to a semi- coherent interface consisting of a regular array of edge interfacial misfit dislocations at a critical film thickness of six monolayers. A second transition to a semicoherent interface consisting of a completely developed network of perpendicularly intersecting misfit dislocations is predicted at thicknesses greater than 150 monolayers. Our simulation results are in excellent agreement with recent experimental data.
Dynamic Hardness of Thin Films and its Thickness Dependence
Authors: Iwasa Mikio , Tanaka Koji , Barnard John A. , Bradt Richard C. 
Published: April 2011

ABSTRACTThin films of indium tin oxide, silica and chromium were deposited on the soda-lime-silica glass substrates with the thickness ranging from 50 to 2000 nano-meter. Their dynamic hardness were measured by the nano-indentation method with the indentation depth from 50 to 200 nano-meter. The hardness of indium tin oxide film increased and that of silica decreased with increasing film thickness. The hardness of chromium was almost constant regardless of film thickness. When the hardness of thin film was higher than that of substrate, the influence of substrate was greater compared with the reverse case. The dynamic hardness of engineering ceramics were about fifty percent higher than the ordinary Vickers hardness, but the ranking order was in good agreement. The Young's modulus from nano-indentation were a little higher than those by resonance method.
Mechanical and Tribological Properties of Zrc/Vc Alloy Films Deposited by Sputtering and Pulsed Laser Deposition
Authors: Brock W. F. , Krzanowski J. E. , Leuchtner R. E. , Legore L. J. , Frankel D. J. 
Published: April 2011

ABSTRACTA study has been conducted on ZrC/VC alloy thin films prepared by both pulsed laser deposition (PLD) and RF magnetron sputtering. The phase formation, wear properties, and hardness of these thin films were examined. An alloy target comprised of 36% VC and 64% ZrC (atomic %) was used to deposit films at 200°, 2000°, and 400° C. The nominal film thickness was 0.6 μm. X-ray diffraction (XRD) analysis revealed these films were solid-solution alloys and showed a preference for (100) orientation for sputter-deposited films and a (110) orientation for laser deposition. More highly oriented films were obtained at elevated temperatures as evidenced by rocking curve measurements on the PLD films. The FWHM of the peaks ranged from 2.2° to 8.3° for films deposited at 400° C and 20° C, respectively.Using time-of-flight quadmpole mass spectrometry (TOFQMS), we performed plume diagnostics to measure particle energies and the thermalization effects of the background gas. In vacuum, typical ion energies ranged from ˜5–100 eV while the neutral atoms had kinetic energies from ˜1–5 eV. Our measurements show that the background gas can be used to selectively thermalize low mass components in the plume. From measured kinetic energies and collision effects of the gas, the changes in crystallographic structure of the alloy with pressure appear to result from collision-induced effects from condensation of the Zr atoms. This ‘heavy’ atom effect may be an important new processing parameter with which to adjust film morphology and crystal texture.
Diamond Coatings on Surface-Modified Carbide Tools Using KrF Pulsed Laser
Authors: Lee Dong-Gu , Singh Rajiv K. 
Published: April 2011

ABSTRACTThe surface of a cemented carbide was modified using a KrF pulsed laser process to achieve a microrough structure, leading to stronger adherence of diamond films to cemented carbide substrates. The surface morphology and roughness were investigated with laser conditions. After the surface modification with the laser and the etching of the modified surface, heat treatment was performed prior to deposition of diamond film in order to observe changes in surface morphology and adhesion. Diamond films were grown by chemical vapor deposition process. The results indicated that the heat treatment of the modified cemented carbide improved the adhesion of diamond films by the recrystallization of tungsten carbides into the fine and long grains. As laser energy for the modification of a cemented carbide increased, the surface roughness increased and tungsten carbide (WC) was transformed to WC1−x(X =0–0.3) and then to W2C.
Correlation of Stress With Photo-Degradation in Hydrogenated Amorphous Silicon Prepared by Hot-Wire CVD
Authors: Han Daxing , Gotoh Tamihiro , Nishio Motoi , Sakamoto Tomonari , Nonomura Shuichi , Nitta Shoji , Wang Qi , Iwaniczko Eugene 
Published: April 2011

ABSTRACTAn innovative bending-beam method is used to study the stress of thin film a-Si:H deposited on thin quartz by hot-wire chemical vapor deposition (CVD) techniques. When the deposition temperature increases from 280 to 440 °C the hydrogen content decreases from 8 to <1 at.%, and the initial compressive stress also decreases from 420 to 74 MPa. We found that there is a 10−4 photo-induced increase of the initial compressive stress under 300 mW/cm2 light-soaking, which can be recovered to the initial value by thermal annealing at 160 °C for 1 h. The results imply that the Si-H bonds contribute to the compressive stress in the a-Si:H film. There is no simple correlation between the stress and the photodegradation of the electronic properties.
Micro-Raman Study of Mechanical Stress in Polycrystalline Silicon Bridges
Authors: Talaat H. , Negm S. , Schaffer H. , Kaltsas G. , Nassiopoulou A. G. 
Published: April 2011

ABSTRACTMicro-Raman spectroscopy is used to study mechanical stress distribution in polycrystalline silicon bridges on cavities micromachined in crystalline Si wafers. The influence of the processing parameters such as the thickness of polycrystalline membrane, the annealing conditions (before or after removal of the sacrificial porous-Si layer ), are studied. The results indicate that the annealing reduces the residual stress by an order of magnitude and that the membrane thickness of 2.5 μm has the least residual stress.
Measurement of Nonuniform Stresses in Semiconductors by the Micro-Raman Method
Authors: Pinardi K. , Jain S. C. , Maes H. E. , Overstraeten R. Van , Willander M. , Atkinson A. 
Published: April 2011

ABSTRACTMicro-Raman measurements axe performed with a focused laser beam. Because of its finite diameter (∼ 1 μm) and penetration depth, the laser beam samples a “large volume” of the sample. In a nonuniformly strained sample, spectra originating from different points are different. Therefore the observed spectrum depends on both the strain distribution in the sample and the absorption coefficient of the laser light. We describe a method to calculate the Raman spectra taking these factors into account. The calculated spectra show excellent agreement with the experimental results.
Fracture Tests Of Polysilicon Film
Authors: Sharpe W. N. , Yuan B. , Edwards R. L. 
Published: April 2011

ABSTRACTA new test approach is presented to measure the fracture toughness of thin films. The polysilicon specimen is a center-cracked panel that is 3.5 μm thick and 3 mm wide with a 100 μm long slot in the center. It is subjected to tensile loading, and the crack-opening displacement is measured by interferometry. The average toughness is 1.4 ± 0.65 MPa-m1/2.
Curvature Of Rectangular Coated Foils With Different Width-To-Length Ratios
Authors: Tran M. D. , Vellinga W. P. , Dautzenberg J. H. 
Published: April 2011

ABSTRACTThis paper concerns the bending of rectangular foils with different width-to-length ratios, coated with a layer with high internal stress. Framework for the interpretation of experimental results is a description of the bending based on geometrically nonlinear elasticity. Calculations indicate that the (mean) biaxial modulus of coatings on foils may be determined by this method. Fully isotropic and isotropic-orthotropic bilayers are considered. Preliminary experimental results, of unbalanced magnetron sputtered PVD TiN coatings on stainless steel foil, are shown to be in qualitative agreement with the geometrically non-linear description of the bending of coated foils, provided anisotropy of the substrate and clamping conditions are taken into account.
Nanoindentation Hardness of Compositionally Modulated Ti/TiN Multilayered Films
Authors: Kusano Eiji , Kitagawa Masaru , Nanto Hidehito , Kinbara Akira 
Published: April 2011

ABSTRACTA detailed study of microhardness of multilayered films has been strongly needed to reveal effects of film layer structures and deposition conditions on the film hardness. A nanoindentation method is a useful method to investigate mechanical properties of thin films prepared on substrate materials. In this respect we have deposited a several types of Ti/TiN multilayered films and estimated their hardness by a nanoindentation method. The desired compositional modulation was obtained by changing the flow rate of N2gas periodically using a computer system. The modulation period has been varied from 10 to 40nm by changing a flow rate control pattern. The total thickness of the film was about 500nm including the underlayer of the TiO2(50nm)/Ti(50nm) multilayer for all samples with different modulation period. Substrates used in the experiment were borosilicate glass and not heated during film deposition. The compositional distribution toward to the film depth orientation was estimated by Auger electron spectroscopy. The dynamic hardness of the films has been estimated by a nanoindenter as a function of the modulation period. It was found that there existed an optimum modulation period of 20nm to enhance the film hardness by multilayer structure.. The maximum value of microhardness obtained for the optimum modulation period was 29GPa, which was much larger than that of the monolithic TiN coating of 15GPa. The hardness measurement results show that the behavior for dynamic hardness was different from that for plastic deformation hardness obtained.