bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nondestructive Characterization of GaN Films Grown at Low and High Temperatures
Authors: Yana C.H. , Yao H.W. , Hove J.M. Van , Wowchak A.M. , Chow P.P. , Han J. , Zavada J.M. 
Published: April 2011

ABSTRACTGaN films grown on GaAs and sapphire substrates by molecular beam epitaxy (MBE) and metalorganic vapor phase epitaxy (MOVPE) at both low and high temperatures (LT and HT) were characterized by Raman scattering and variable angle spectroscopic ellipsometry (VASE). Optical phonon spectra of GaN films are obtained through back-scattering geometry. Crystal quality of these films was qualitatively examined using phonon line-width. Phonon spectra showed that the HT GaN has wurtzite crystal structure, while LT GaN and GaN/GaAs have cubic-like structures. Thickness nonuniformity and defect-related absorption can be characterized by pseudo dielectric functions directly. Surface roughness also can be determined by using an effective-medium approximation (EMA) over-layer in a VASE analysis. Anisotropic optical constants of GaN, both ordinary and extraordinary, were obtained in the spectral range of 0.75 to 6.5 eV with the consideration of surface roughness, through the small and large angles of incidence, respectively. The film thickness of the GaN was accurately determined via the analysis as well.
Effects of Reverse Biased Floating Voltage at Source and Drain During High-Field Electron Injection on the Performance of NMOSFETS
Authors: Jarwal R. K. , Misra D. 
Published: April 2011

ABSTRACTWe have examined the effects of reverse biased floating voltage at the source and drain junctions during constant current high-field electron injection on the performance of NMOSFETs. Device parameter degradation was studied when electrons were injected from both gate and substrate. Hole trapping and electron trapping (observed from threshold voltage degradation) were found to be enhanced with reverse biased floating voltage for devices subjected to substrate injection. On the other hand, damages in the devices subjected to gate injection were found to be minimal dependent on reverse biased voltage. Increase in current density due to reduction in effective channel length is believed to be the cause of modified device characteristics. Transconductance degradation for both substrate injection and gate injection was found to have minimal dependence on reverse biased voltage. An asymmetry in the distribution of electron traps at the gate-oxide and substrate-oxide interfaces was observed.
Dielectric Properties of Bi2Ti2O7 Thin Films With (111) Orientation
Authors: Wang Zhuo , Huang J. , Wang S.W. , Hong X.X. , Hou Y. , Wang M. , Shang S.X. , Wang H. , Hu X.B. , Wang Yuguo 
Published: April 2011

ABSTRACTBismuth titanate thin films have been prepared on silicon by metalorganic decompositionMOD) technique with bismuth nitrate and titanium butoxide as source materials. The growth procedure of the Bi2Ti2O7 thin films is discussed in this paper. The surface morphology of the Bi2Ti2O7 film was investigated by using Electric Force Microscope (EFM), and the crystallization of the films was studied by x-ray diffraction (XRD). Bismuth titanate thin film prepared on (100) silicon substrate showed strong (111) orientation. Its dielectric properties and the current-voltage (I-V) characteristics were measured. The dielectric constant of the Bi2Ti2O7 thin films vs. frequency, in the temperature range of 100-800 °C, were studied. The dielectric constant and the dielectric loss for Bi2Ti2O7 are 118 and 0.07 respectively at 100KHz. For the Bi2Ti2O7 films with 0.4µm in thickness annealed at 580 °C for 40 minutes, their leakage current density is 4.06×10−7 A/cm2 at an applied voltage of 15V.The ferroelectric phase transition has been observed distinctly and the Curie temperature was determined for the Bi2Ti2O7 ceramic films. Capacitance vs. temperature was measured from 27-800 at 1KHz, 100KHz, 100KHz and 1MHz.
Low-Temperature Direct-Oxidation of Si Using Activated Oxygen Generated by Tungsten Catalytic Reaction
Authors: Kudo Manabu , Izumi Akira , Matsumura Hideki 
Published: April 2011

ABSTRACTUltra-thin silicon dioxide films can be formed at temperatures as low as 220°C by direct oxidation of Si, using active oxygen species generated by tungsten catalytic reaction in a catalytic chemical vapor deposition (Cat-CVD) system. The structural and electrical properties of such a films are investigated. It is found that the density of Si atoms in intermediate oxidation states and the density of films determined from etch rate in dilute HF solution were comparable to those of the films by a conventional thermal oxidation at 900°C. The electrical properties, breakdown electric field and leakage current were also comparable to those of thermally oxidized films.
Structural, Optical and Electrical Characteristics of Silicon Carbon Nitride
Authors: Chen L. C. , Wu C. T. , Wen C.-Y , Wu J.-J. , Liu W. T. , Liu C. W. 
Published: April 2011

ABSTRACTDielectric layers of thin silicon carbon nitride (SiCxNy) films have been prepared by ion beam sputtering deposition (IBD). For submicron metal-insulator-Si (MIS) based device applications, a dielectric of low interface roughness, increased capacitance/area with lower leakage on decreasing scale is highly desirable. We address these aspects for the IBD SiCxNy films on p-type Si and present their structural, optical and electrical characteristics as a function of the deposition conditions. Ultraviolet-visible transmittance and spectroscopic ellipsometry were employed to study the optical properties of the SiCxNy films. For electrical measurements, Al gate electrodes were fabricated on SiCxNy films to form metal-nitride-silicon (MNS) diodes. Characteristic I-V and photoconductivity measurements of the MNS are presented.
Study of Stress-Induced Leakage Current in Thin Oxides Stressed by Corona Charging in Air: Relationship to GOI Defects
Authors: Wilson M. , Lagowski J. , Savtchou A. , Marinskiy D. , Jastrzebski L. , D'amico J. 
Published: April 2011

ABSTRACTCorona charging in air combined with non-contact oxide charge measurement with a contact potential difference probe provides an unique possibility for fast monitoring of electron tunneling characteristics without preparation of MOS capacitors. It has also been found tha corona charging of thin oxides in the tunneling range is very effective in generating stressinduced leakage current. In this work we demonstrate the sensitivity of the corona stressinduced leakage current magnitude to gate oxide integrity defect density. The experimenta results cover three of the most common gate oxide integrity defects, namely: 1 – the defect induced by heavy metals (Fe.Cu) at a practically important low concentration range of 1×1010 to 1×1011 atoms/cm3: 2 – the defects originating from interface roughness and 3–the defects related to crystal originated particles.At low corona stress fluence, these defects play no role in the tunneling characteristics which follow ideal Fowler-Nordheim characteristics for oxides 50Å or thicker and a contribution from a direct tunneling current for thinner oxides. At high corona stress fluences, gate oxide integrity defects control the magnitude of stress-induced leakage current measured at constan oxide field. It is suggested that the gate oxide integrity role is associated with the enhanced rate of the trap generation during stress. It is noted that the present findings employ a novel methodology for gate oxide integrity monitoring based on corona charging and contact potential difference measurement.
Multi-Million Atom Molecular-Dynamics Simulations of Stresses in Si(111)/Si3N4 Nanopixels
Authors: Bachlechner Martina E. , Omeltchenko Andrey , Walsh Phillip , Nakano Aiichiro , Kalia Rajiv K. , Vashishta Priya , Ebbsjö Ingvar , Madhukar Anupam 
Published: April 2011

ABSTRACTThe stress distribution in Si(111)/Si3N4(0001) and Si(111)/a-Si3N4 nanopixels are studied using molecular dynamics simulations on parallel computers. Bulk Si is described by the Stillinger-Weber potential and Si3N4 is represented by a combination of two- and three-body interactions that include steric, charge transfer, polarizability and covalent forces. The charge transfer at the interface is extracted from self-consistent electronic structure calculations. The molecular dynamics simulations for Si(111)/a-Si3N4 nanopixels involve two pixel sizes: 25nm and 54 nm (the systems consist of 3.7 million and 10 million atoms, respectively). In both systems we find stress domains at the interface, which extend into the silicon substrate. The nature of the stress domains is discussed.
Roles of Primary Hot Hole and FN Electron Fluences in Gate Oxide Breakdown
Authors: Li M. F. , He Y. D. , Ma S. G. , Cho Byung Jin , Lo K. F. 
Published: April 2011

ABSTRACTIn this work, we report the link between the primary hot hole and Fowler Nordheim (FN) electron injections in oxide breakdown mechanism. A simple breakdown model is established. The experimental method is carefully designed to measure the primary hot hole fluence and FN electron fluence separately and accurately. The calculation based on our model is in very good agreement with our experiments. Oxide breakdown is stimulated by a combined effect when the sum of the trap density Dpri activated by primary hot hole injection and the trap density Dn activated by FN electron injection reaches a critical value Dcri. The hole is two orders of magnitude more effective than FN electron in causing breakdown. Since primary hot hole injection may occurs under many realistic device operation in the circuit, existing oxide lifetime projected from conventional TDDB measurement by only applying FN stress is overestimated in many cases. The model demonstrated in this work lays the groundwork in approaching a more appropriate way for predicting the oxide reliability and lifetime.
The Effect of Film Thickness on Stress and Transformation Behavior in Cobalt Thin Films
Authors: Hesemann H. Th. , Müllner P. , Kraft O. , Arzt E. 
Published: April 2011

AbstractPure cobalt shows a martensitic transformation from a face-centered-cubic to an hexagonal-close-packed phase. In this work it is chosen as a model-system to investigate the influence of film thickness, film stress and microstructure on the martensitic transformation in thin films.Co films of 0.2 μm to 3.0 μm thickness were sputter-deposited on Si substrates. This paper presents wafer curvature measurements during temperature cycles of these films and results obtained by focused ion beam microscopy. Upon repeated thermocycling, the martensitic transformation was repeatedly observed in 3 μm thick films, whereas it was not found in 0.2 μm Co films. A stress drop on heating as well as on cooling accompanied the martensitic transformation. It was observed that the stress level at which the transformation occurs can be changed by varying the film thickness or maximum temperature of the temperature cycles. As a result, the martensitic start temperature decreases with increasing stress. It is concluded that the film stress is a critical parameter which strongly affects the martensitic transformation.
In-Situ Characterization of Stress Development in Gelatin Film During Controlled Drying
Authors: Lu Mengcheng , Tam Siu-Yue , Schunk P. Randall , Brinker C. Jeffrey 
Published: April 2011

AbstractDrying of gelatin films was studied by an in-situ cantilever beam method combined with spectroscopic ellipsometry, enabling measurement of the stress development, film shrinkage and compositional change during the drying process. Experiments are carried out under different drying conditions (such as drying extent variation, drying rate variation). The film experiences stress relaxation that indicates visco-elastic relaxation or plastic deformation happened during drying process. Plastic deformation is verified by carefully reversing the drying process, however, the plastic deformation accompanied by visco-elastic relaxation complicates the case of finding the value of the yield stress.
Micro-Wear Scan Test on the Carbon Overcoats as Thin as 6 NM or Less
Authors: Wu T. W. , Scharf Thomas W. , Zhang Hong , Barnard John A. 
Published: April 2011

AbstractNitrogen-doped carbon (CNX) overcoats, ranging from 1 to 6nm in thickness, were deposited on magnetic recording disks by a DC-sputtering process. A critical load, based on the first occurrence of coating damage, was used as a semi-quantitative measure of the mechanical strength of these overcoats. It was found that the critical load decreased in a nearly linear manner with the CNX thickness from 6nm down to ∼2nm regime. However, the 1nm thick CNX coating deviated from this trend with a significant decrease in critical load. High-resolution SEM was employed to find the critical loads as well as to reveal the details of the coating wear morphology and the CNX failure mechanism.
Elastic Constants of Diamond Like Carbon Films by Surface Brillouin Scattering
Authors: Ferrari A. C. , Robertson J. , Pastorelli R. , Beghi M. G. , Bottani C. E. 
Published: April 2011

AbstractThe elastic constants of thin Diamond-Like Carbon (DLC) films supply important information, but their measurement is difficult. Standard nanoindentation does not directly measure the elastic constants and has strong limitations particularly in the case of hard thin films on softer substrates, such as tetrahedral amorphous carbon on Si. Surface acoustic waves provide a better mean to investigate elastic properties. Surface Brillouin scattering (SBS) intrinsically probes acoustic waves of the wavelength which is appropriate to test the properties of films in the tens to hundreds of nanometers thickness range. SBS can be used to derive all the isotropic elastic constants of hard-on-soft and soft-on-hard amorphous carbon films of different kinds, with thickness down to less than 10 nm. The results help to resolve the previous uncertainties in mechanical data. The Young's modulus of tetrahedral amorphous carbon (ta-C) turns out to be lower than that of diamond, while the moduli of hydrogenated ta-C (ta-C:H) are considerably lower than those of ta-C because of the weakening effect of C-H bonding.
Nanomechanical Properties of Amorphous Carbon and Carbon Nitride Thin Films Prepared by Shielded Arc Ion Plating
Authors: Tajima N. , Saze H. , Sugimura H. , Takai O. 
Published: April 2011

AbstractHydrogen free amorphous carbon (a-C) and carbon nitride (a-C:N) were synthesized by means of shielded arc ion plating in which a shielding plate was inserted between a target and a substrate in order to reduce macroparticle deposition onto the substrate. Using a graphite target as a cathode, thin films of a-C and a-C:N were prepared in an arc discharge plasma of argon or nitrogen gas, respectively, at a pressure of 1 Pa. Based on nanoindentation, mechanical properties of these films were studied in relation to substrate bias voltage (VS). The a-C films prepared at VS ranging from −50 to −200 V consisted of diamond-like phase and showed hardness higher than 20 GPa with its maximum of 35 GPa at Vs = −100 V. However, hardness of the films deposited at VS < -300 V was less than 7 GPa indicating that the films were converted to graphite-like phase due to excessive ion impact in Ar plasma. Wear resistance of the a-C films was closely related to their hardness. Namely, a harder a-C film was more wear resistant. On the contrary, hardness of the a-C:N films was less dependent on VS. It remained in the range of 10 to 15 GPa and was much lower than the maximum hardness of the a-C films. Nevertheless, the wear resistance of the a-C:N films was comparable to or much better than the a-C films. In particular, the a-C:N film prepared at VS = -300 V was so wear resistant that the film showed no apparent wear when rubbed with a diamond tip less than 100 nm in tip-diameter at a contact force of 20 μN. The presence of β-C3N4 like phase characterized by a Nls XPS peak at 400.5 eV has found to be crucial for high wear resistance of the a-C:N films.
Micromechanics-Based Modeling of Interfacial Debonding in Multilayer Structures
Authors: Klein P. A. , Gao H. , Vainchtein A. , Fujimoto H. , Lee J. , Ma Q. 
Published: April 2011

AbstractClassical approaches to modeling fracture have proved successful in applications for which the highly deformed region near a crack tip is small compared to any other relevant dimensions in the structure. The classical theory relies on phenomenological criteria for material failure that lack a physics-based description of the fracture process itself. Small scale, thin film structures pose difficulties for analysis by these approaches because they contain complicated geometry and many interfaces within the fracture process zone itself. Moreover, plastic flow in metal layers is often severely constrained by the surrounding structure, causing the plastic dissipation part of the overall fracture energy consumed by debonding to be a strong function of geometry. Therefore, it can no longer be regarded as an intrinsic material property. To improve the fracture characterization of these structures, one must develop a physically sound methodology capable of separating the contribution of plastic flow, and other sources of dissipation, from the work of adhesion consumed at the crack tip. In this study, we investigate the parameters affecting energy dissipation by interfacial debonding in a multilayered structure. Interlayer decohesion is modeled using the Virtual Internal Bond constitutive model. We compare our predicted variations in the macroscopic fracture energy with experimental results for varying layer geometry. We also characterize the effect of variations in material properties and other experimental uncertainties in the resulting debonding behavior.
Effect of Annealing on Microstructure and Properties of Al-Ti Multilayered Films
Authors: Mitra R. , Madan A. , Hoffman R. A. , Chiou W. A. , Weertman J. R. 
Published: April 2011

AbstractAl-Ti multilayered films were deposited by magnetron sputtering of Al and Ti targets on to Si (100) or NaCl substrates. The bi-layer thickness was 16 nm with Ti constituting 12% of the total thickness. The films were subsequently annealed in vacuum at 400°C for periods between 2 and 24 h. In the course of the annealing, interdiffusion and chemical reaction between Al and Ti layers led to the precipitation of Al3Ti particles. Plan view and cross-section TEM examination of as-deposited and annealed films were performed to study the microstructural evolution, and to estimate the Al grain and AI3Ti particle size distributions. Cross-section TEM and X-ray diffraction showed a well-defined layered structure in the as-deposited films. The microstructure was found to be metastable in the first 6 h of annealing, with Al-Ti multilayers being gradually replaced by an AI-AI3Ti composite structure. The Al3Ti particles were uniformly distributed throughout the film. X-ray and electron diffraction analyses showed that Al3Ti possessed the ordered DO22 structure. The hardness of the Al-Ti films in as-deposited and annealed conditions was determined using a nanoindenter and the data have been correlated with the microstructural changes with annealing.
Microbridge Testing of Thin Films Under Small Deformation
Authors: Zhang T. Y. , Su Y. J. , Qian C. F. , Zhao M. H. , Chen L. Q. 
Published: April 2011

AbstractThe present work proposes a novel microbridge testing method to simultaneously evaluate the Young's modulus, residual stress of thin films under small deformation. Theoretic analysis and finite element calculation are conducted on microbridge deformation to provide a closed formula of deflection versus load, considering both substrate deformation and residual stress in the film. Silicon nitride films fabricated by low pressure chemical vapor deposition on silicon substrates are tested to demonstrate the proposed method. The results show that the Young's modulus and residual stress for the annealed silicon nitride film are respectively 202 GPa and 334.9 MPa.
Evaluation of Conductive Region in PZT film Induced by Low Temperature Hydrogen Treatment on PT/PZT/PT Capacitor
Authors: Kanaya Hiroyuki , Kumura Yoshinori , Kunishima Iwao , Tanaka Shin-Ichi , Iwamoto Tsuyoshi , Takahagi Yukio 
Published: April 2011

AbstractA conductivity difference in a PZT film in a Pt/PZT/Pt capacitor was found by novel charged-up SIMS analyses for the first time. The charged-up SIMS technique was useful for evaluating the conductivity profile in the PZT film. It was found that the conductive region existed in an as-prepared PZT film near the bottom Pt electrode. After hydrogen plasma treatment at 45°C, the conductive region increased in the PZT film near the top electrode. Electrical measurements showed that the leakage current of the capacitor increased after hydrogen treatment. The hydrogen was expected to reduce PZT both at grain boundaries and the electrode-PZT interfaces, and to form the conductive region, which induced an increase in leakage current.
Relationships Between Bi/Ti Composition Ratio and O2 Concentration for Orientation Control of Bi4Ti3O12 Thin Film Using Mocvd Method
Authors: Kijima Takeshi 
Published: April 2011

AbstractPt/Bi2SiO5/Si (MIS) and Pt/200nm-Bi4Ti3O12/Pt/30nm-Bi2SiO5/Si (MFMIS:Metal/ Ferroelectric/ Metal/Insulator/Semiconductor) structures were prepared by MOCVD. Oxygen concentration and the Bi/Ti composition ratio determine Bi4Ti3O12 orientation and Bi4Ti3O12 volume in the film, respectively. When the oxygen concentration and the Bi/Ti composition ratio was 33% and 0.65, (001) Bi4Ti3O12 film with the dielectric constant of 40 was obtained. In addition, the capacitance-vs-voltage (C-V) measurement of the Pt/Bi2SiO5/Si structure exhibits normal MIS C-V characteristics. The C-V characteristics of Pt/Bi4Ti3O12/Pt/ Bi2SiO5/Si structure have ferroelectric switching properties with a memory window of about 2.OV Moreover, it is found that the capacitance at zero-bias remains constant for over 24 h.
Displacement Charge Patterns and Ferroelectric Domain Wall Dynamics Studied by In-Situ Tem
Authors: Krishnan A. , Treacy M. M. J. , Bisher M. E. , Chandra P. , Littlewood P. B. 
Published: April 2011

AbstractWe have observed the growth of domains in ferroelectric barium titanate and potassium niobate using a transmission electron microscope. When domains move in response to electric fields we see a scaling effect where the fine scale domain structure is activated first, followed by larger length-scale patterns. Curvature and tilting of domain walls leads to local uncompensated displacement charge and external fields can interact with these charged walls. In this paper, we posit that the presence of displacement charge on domain walls is important for polarization switching. Charge-neutral domain configurations are in a lower energy state and are harder to switch. We argue that the number of charge-neutral, low energy domain configurations can increase with time. This mechanism provides an intrinsic contribution to ferroelectric fatigue.
Electrical Properties of Low-Temperature Processed PZT Thin Films with Preferred Orientations
Authors: Suzuki H. , Kondo Y. , Kaneko S. , Hayashi T. 
Published: April 2011

AbstractFerroelectric Pb(Zr0.53Ti0.47)O3 (PZT) thin films with preferred orientations were successfully deposited on the Pt/Ti/SiO2/Si wafer at low temperature of 525°C by the chemical solution deposition from molecular-designed precusor solution with 20 mol % excess lead than a stoichiometric composition. The composition of the resultant PZT thin films showed slightly lead excess than a stoichiometric composition. In addition, orientation of the resultant PZT thin films could be controlled by changing the pre-annealing temperature or insertion of thin PbO layer, which affected the interfacial state between Pt electrode and PZT thin films. The electrical properties of the resultant PZT thin films were also affected by the orientation of the resultant films. As a result, orientation of the low-temperature processed PZT thin films had large effect on the electrical properties of the resultant films.