Dependence Of Surface Roughness Research Articles

Room temperature, ion energy-controlled deposition of silicon nitride films in a SiH4-N2 plasma

In this study, silicon nitride films were deposited in SiH4-N2 plasma using a plasma-enhanced chemical vapor deposition system at room-temperature. The radio frequency bias power impact on the films characteristics (deposition rate, refractive index, and surface roughness) was examined. Ion energy information (energy level, energy flux) collected using an ion energy analysis system was correlated with the film characteristics. Increasing the bias power increased the ion energy, more noticeably with the high ion energy. For the same variations in the bias power, the ion energy flux initially decreased considerably and then varied little. A similar variation was noticed in both film characteristics. Both the deposition rate and the refractive index were strongly correlated with the ratio of high ion energy to low ion energy rather than high or low ion energy. A similar dependency was also observed for the refractive index. The dependency of surface roughness changed from ion energy to ion energy flux. The roles of the ion energy flux were further examined by implicating them in AFM images. The low ion energy flux was identified as a contributor to the extreme peaks that significantly deteriorated the surface roughness. The highest deposition rate, highest refractive index, and smallest surface roughness obtained were 183 A/min, 2.06, and 0.230 nm, respectively.

Effect of Metallic Composition on Electrical Properties of Solution-Processed Indium-Gallium-Zinc-Oxide Thin-Film Transistors

We report the combinatorial study on surface morphology and electrical properties of solution-processed amorphous indium-gallium-zinc-oxide (a- IGZO) thin-film transistors (TFTs). The sol-gel-processed a-IGZO thin films typically have shown an amorphous structure and critical dependence of mobility, carrier concentration, and surface roughness on the In, Ga, and Zn molar ratio in the solution phase. Based on efficient control of the metallic components from the sol-gel process, the solution-processed a- IGZOT FTs with a mobility of 0.5-2 cm2/V ·s, on/off current ratio > 107, and a subthreshold slope of as steep as 1.5 V/dec were obtained.

Investigation of film surface roughness and porosity dependence on lattice size in a porous thin film deposition process

The dependence of film surface roughness and porosity on lattice size in a porous thin film deposition process is studied via kinetic Monte Carlo simulations on a triangular lattice. For sufficiently large lattice size the steady-state value of the expected film porosity has a weak dependence on the lattice size and the steady-state value of the expected surface roughness square varies linearly with lattice size. An analysis of the film morphology based on a stochastic partial differential equation description of the film surface morphology supports and explains the findings of the numerical simulations.

Advanced Modeling and Accurate Characterization of a 16 Gb/s Memory Interface

As the input/output (I/O) data rate increases to several gigabits per second, determining the performance of high-speed interfaces using conventional simulation and measurement techniques is becoming very challenging. The models of the interconnects have to be broadband and accurate to represent high frequency and second-order effects such as frequency dependence of dielectric losses and surface roughness. The large and small signal behaviors of the transmitter and receiver circuitries have to be correctly represented in link analysis. In addition, the system simulation needs to properly capture the interactions between the circuits and interconnect subsystems to optimize the overall system. However, determining the values of the critical link parameters and their correlations can be complicated. Some of the key parameters are not deterministic and some cannot be observed directly. A combined modeling and measurement approach is indispensable to determine the performance of high-speed links. This paper presents the modeling and characterization techniques employed in the design and verification of a 16 Gb/s bidirectional asymmetrical memory interface. Direct frequency and time-domain methods as well as indirect techniques based on bit-error-rate testing are used to model and determine important link parameters. Complex de-embedding procedures are utilized to extract parameters from externally observed data. On-chip measurements are also used to complement off-chip instrumentation and accurately measure the true performance of the link. The modeling and characterization of prototypes are also discussed and model-to-hardware correlations are presented at component and system levels. Based on both simulation and measurement results, the behavioral model of the complete system is constructed and statistical simulation technique is used to predict the yield and performance at low bit error rate.

Structural, morphology and electrical properties of layered copper selenide thin film

Abstract Thin films of copper selenide (CuSe) were physically deposited layer-by-layer up to 5 layers using thermal evaporation technique onto a glass substrate. Various film properties, including the thickness, structure, morphology, surface roughness, average grain size and electrical conductivity are studied and discussed. These properties are characterized by X-ray diffraction (XRD), atomic force microscopy (AFM), ellipsometer and 4 point probe at room temperature. The dependence of electrical conductivity, surface roughness, and average grain size on number of layers deposited is discussed.

Diffraction equations for weak scattering reflective surface

In order to investigate the surface roughness dependence of speckle patterns, the complex-amplitude distribution of the speckle field should be obtained first. In previous studies, most investigators have treated this problem using the Fresnel or Fraunhofer diffraction equation. But for a weakly scattering reflective surface, when the observation plane is not parallel to the object plane, the Fresnel and Fraunhofer diffraction equations become inapplicable. Therefore, a reflective surface diffraction model (RSDM) is formed. When the difference between the RSDM and the transmission aperture diffraction model (TADM) is considered, then a general diffraction equation is presented. Considering the variations of the near-field approximation caused by coordinate system rotation, the near-field diffraction equation is derived. By introducing the far-field approximation, the far-field diffraction equation is obtained. The physical meanings of factors in the new equations are interpreted. Comparisons between the Fresnel and Fraunhofer diffraction equations and the newly derived ones show that the former are just the special cases of the latter. Finally, an application of these new diffraction equations is proposed.

Surface and electrical properties of NiCr thin films prepared by DC magnetron sputtering

Several batches of NiCr alloy thin films with different thickness were prepared in a multi-targets magnetron sputtering apparatus by changing sputtering time while keeping sputtering target power of Ni and Cr fixed. Then the as-deposited films were characterized by energy-dispersive X-Ray spectrometer (EDX), Atomic Force Microscope (AFM) and four-point probe (FPP) to measure surface grain size, roughness and sheet resistance. The film thickness was measured by Alpha-Step IQ Profilers. The thickness dependence of surface roughness, lateral grain size and resistivity was also studied. The experimental results show that the grain size increases with film thickness and the surface roughness reaches the order of nanometer at all film thickness. The as-deposited film resistivity decreases with film thickness.

Experiments and validation of a model for microparticle detachment from a surface by turbulent air flow

This work presents a revised model for microparticle detachment from a surface by turbulent air flow. The model accounts for the dependence of the effective surface roughness at the microparticle/surface interface on the contact radius. This dependence is quantified by surface scanning using atomic force microscopy. A series of detachment experiments of glass microparticles, ranging from 30 to 110 μ m in diameter, from a glass substrate, was conducted to validate the revised model. The model and data were found to agree at the 95% confidence level. The model sensitivity to five different physical factors was analyzed using design-of-experiments methodology with a full-factorial-design layout. The uncertainty in the threshold-detachment free-stream velocity that arose from the inherent variability in the model inputs was quantified using Monte Carlo simulations. The uncertainty that occurs in the threshold-detachment free-stream velocity when there is no specific information on surface roughness was estimated.

Non-monotonous dependences of thin film surface roughness on substrate temperature and deposited atom flux

Experimentally observed non-monotonous dependences of thin films surface roughness on substrate temperature and flux of deposited atoms are analysed by kinetic rate equation model. The modelling results show good qualitative agreement with the experiment and explain an unusual phenomenon of surface roughness. It is shown that non-monotonous dependence of surface roughness on substrate temperature and deposition flux is determined by the size of islands and diffusivity of atoms on the surface. From present analysis it follows that the formation mechanisms of non-monotonous dependences of the surface roughness on temperature and deposition flux are of different origin. The mechanisms are qualitatively analysed in the presentpaper. Keywords: surface roughness, island films deposition, surface diffusion, kinetic modelling

Evaluation of Ocean-Wave Dependence of Sea Surface Roughness Using Wave-Boundary Layer Model

Ocean-wave dependence of sea surface roughness is investigated using a wave boundary layer model, which is based ona recently obtained knowledge of air-sea interaction. The momentum flux is estimated by solving the model with meteorologicaland ocean wave information, which is obtained by carrying out the WRF and WWIII simulations. When windwaveis predominant, the results show clear relationships between Charnock coefficient and the wave age, between theroughness normalized by significant wave height z0/Hs and the wave age, and between the z0/Hs and the wave steepness.On the other hand, when swell is predominant, the results do not show clear dependence of Charnock coefficient on thewave age, and that of z0/Hs on the wave steepness, although that of z0/Hs on the wave age is observed.

617 コンロッド軸受の弾性流体潤滑における表面粗さと潤滑油粘度の圧力依存性(GS-7 排ガス計測・後処理・潤滑)

617 コンロッド軸受の弾性流体潤滑における表面粗さと潤滑油粘度の圧力依存性(GS-7 排ガス計測・後処理・潤滑)

Influence of buffer layers on the texture and magnetic properties of Co/Pt multilayers with perpendicular anisotropy

AbstractA study on the buffer layer dependence of film texture, surface roughness, and magnetization reversal mechanism in Co/Pt multilayers is presented. Four different buffers are used: (A) 10 nm Cu, (B) 5 nm Ta/10 nm Cu, (C) 5 nm Ta/10 nm Cu/5 nm Ta, and (D) 5 nm Ta/10 nm Cu/5 nm Ta/10 nm Cu. The growth of [2 nm Pt/0.5 nm Co]5/2 nm Pt on top of these buffer layers results in a large variation of film textures and surface morphologies. Samples with a Cu buffer (A) exhibit a low degree of film texture and are relatively rough. MOKE and MFM measurements on these films reveal that the magnetization reverses by the nucleation of numerous small domains due to a large dispersion of the activation energy barrier. Buffer layer structures where the first layer consists of Ta, on the other hand, result in (111)‐textured Co/Pt multilayers with a more regular surface morphology. In these samples, magnetization reversal proceeds by fast domain wall movement. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Microstructure and surface morphology of YSZ thin films deposited by e-beam technique

In present study yttrium-stabilized zirconia (YSZ) thin films were deposited on optical quartz (amorphous SiO 2), porous Ni–YSZ and crystalline Alloy 600 (Fe–Ni–Cr) substrates using e-beam deposition technique and controlling technological parameters: substrate temperature and electron gun power which influence thin-film deposition mechanism. X-ray diffraction, scanning electron microscopy (SEM), and atomic force microscopy (AFM) were used to investigate how thin-film structure and surface morphology depend on these parameters. It was found that the crystallite size, roughness and growth mechanism of YSZ thin films are influenced by electron gun power. To clarify the experimental results, YSZ thin-film formation as well evolution of surface roughness at its initial growing stages were analyzed. The evolution of surface roughness could be explained by the processes of surface mobility of adatoms and coalescence of islands. The analysis of these experimental results explain that surface roughness dependence on substrate temperature and electron gun power non-monotonous which could result from diffusivity of adatoms and the amount of atomic clusters in the gas stream of evaporated material.

Influence of Structural Non-Stationarity of Surface Roughness on Morphological Characterization and Mechanical Deformation of Rock Joints

Structural non-stationarity of surface roughness affects accurate morphological characterization as well as mechanical behaviour of rock joints at the laboratory scale using samples with a size below the stationarity threshold. In this paper, the effect of structural non-stationarity of surface roughness is investigated by studying the scale dependence of surface roughness and mechanical behaviour of rock joints. The results show that the structural non-stationarity mainly affects the accurate characterization of the surface roughness of the fracture samples. It also controls the amount and location of the contact areas during shear tests, which in turn affects the mechanical properties and asperity degradation of the samples. It is concluded that for accurate determination of the morphological and mechanical properties of rock joints at laboratory and field scales, samples with size equal to or larger than the stationarity threshold are required.

Quantitative description of polychloroprene and piperylene–styrene blend films surface morphology

AbstractSurface morphology of polychloroprene (CR) and piperylene–styrene copolymer (PSC) blend films was investigated by atomic force microscopy. The dependence of the blend films surface roughness on PSC content was studied with both fractal and correlation analyses. Gaussian profiles for the height distribution upon blend composition were observed. The topographical images of CR/PSC blends have been characterized by root‐mean‐square roughness, lateral parameter, and fractal dimension values. The analysis showed that quantitative description of surface roughness leads to the differentiation components of polymers blends. Lateral parameter and fractal dimension values of CR films were similar to those of CR/PSC 60/40 wt% blend films. This effect is associated with CR enrichment at the blend film surface. POLYM. ENG. SCI., 47:824–829, 2007. © 2007 Society of Plastics Engineers

Properties of films obtained from aqueous polymer dispersions: study of drying rate and particle polydispersity effects

The formation of polymer films obtained from latexes and their structural features have been investigated with the aid of a Monte Carlo simulation modelling and atomic force microscopy. The effects of particle size polydispersity and solvent drying rate on film structure, permeability and roughness have been studied. It has been shown that slow drying permits the formation of films with relatively low porosity and smooth surfaces. Polydispersity in the particle size leads to a weakening of the particle layering and thereby to a reduction in film barrier properties. Theoretical calculations indicate the existence of a local nonlinear dependence of film surface roughness on drying velocity. The correlation between film surface roughness and porosity has also been established.

Growth of AlGaN Epitaxial Film with High Al Content byMetalorganic Chemical Vapour Deposition

A high-Al-content AlGaN epilayer is grown on a low-temperature-depositedAlN buffer on (0001) sapphire by low pressure metalorganic chemicalvapour deposition. The dependence of surface roughness, tiltedmosaicity, and twisted mosaicity on the conditions of the AlGaN epilayerdeposition is evaluated. An AlGaN epilayer with favourable surfacemorphology and crystal quality is deposited on a 20 nmlow-temperature-deposited AlN buffer at a low V/III flow ratioof 783 and at a low reactor pressure of 100 Torr, and the adduct reactionbetween trimethylaluminium and NH3 is considered.

MD simulation of sputtering on surface index and surface roughness dependence

Low-energy sputtering is studied through molecular dynamics (MD) and binary-collision approximation (BCA) simulations. First, MD simulations as a preliminary study are performed for 5 keV Ar impacts on a Cu target. When random numbers gave the direction of the target crystal axis for each impact, the total sputtering yield almost agreed with the experimental yield of a polycrystalline Cu target. Second, we performed MD and BCA simulations for self-sputtering of W with an incident energy of 100 eV and incident angles of 0°–85°. We found that the many-body collision results in high-yield sputtering at grazing incidence. The incident angle dependence of sputtering yields fade out for an MD result with a rough surface.

An alternative approach to sea surface aerodynamic roughness

The dependence of sea surface roughness on the wave parameters was investigated using measurements from the Humidity Exchange over the Sea Main Experiment (HEXMAX). This site was 18 m of water depth and was 9 km offshore in the North Sea. We examined the relationships among wave height (Hs), friction velocity (u*) and wave age (cp/u* or cp/U10N) using regression analysis and explored the relationship between dimensionless variables u*(gTp)−1 and U10N2(gHs)−1 by dimensional analyses, where g is the acceleration due to gravity (for which we use 9.81 m s−2); Tp is period of the waves at the peak of the wave spectrum, defined as Tp = 2πcp/g where cp is the phase velocity of the peak wave spectrum; and U10N is horizontal wind speed at 10‐m height under the neutral condition. When the derived results are combined with the neutral wind profile equation, we find that the relationship among friction velocity (u*), neutral 10‐m wind speed (U10N) and phase velocity (cp) is u* = a2/3U10N4/3/cp1/3 where a is an empirical constant, and a = 6.7 × 10−3 for this site. The relationship between aerodynamic roughness length (z0) and wave age and the relationship between the neutral drag coefficient (CDN) and wave age are derived accordingly. The present parameterization schemes were tested using an independent data set, and they work in moderate wind speed.

Surface roughness and material removal in fluid jet polishing

Based on experiments, the dependence of material removal and surface roughness on the characteristics of abrasive particles, on the workpiece, and on other process parameters such as working pressure and incidence angle in fluid jet polishing (FJP) technology were investigated. Experimental results show a volume removal rate that is approximately proportional to the square root of the Young's modulus (E) and inversely proportional to the square of the Knoop hardness (Hk) of glass. Similarly, surface roughness is also determined in FJP by elastic stiffness E and plastic parameter Hk. The influence of the incidence angle on surface roughness and material removal were studied, and a linear dependence of material removal on the working pressure was obtained. Further, it was found that an optical-quality surface can be achieved by use of Cerox 1650 abrasive particles in FJP and can satisfy the requirements of modern optical manufacturing.