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The impedance method is developed for the in-situ determination of electroactive RMS roughness of the electrode for different electrochemical systems. Three electrochemical systems are analyzed to show the wider applicability of this method, viz., (i) rough gold electrode in RTIL medium containing ferrocene, (ii) rough platinum electrode in a mixture of glycerol and water containing potassium ferro/ferricyanide, (iii) drop casted rGO/glassy carbon electrode in aqueous sodium nitrate containing potassium ferro/ferricyanide. The electrochemical impedance spectroscopy (EIS) under reversible electron transfer condition on a rough electrode has an intermediate frequency domain with an anomalous Warburg response. When the diffusion length ( D / ω ) becomes equal to the RMS roughness at a characteristic frequency ( ω M ) which is manifested in experimental EIS data as a maximum point in phase angle, where D is the diffusion coefficient of an electroactive species. The frequency range: ( ω M / 50 ≤ ω ≤ 5 ω M ) represents the anomalously enhanced diffusion which is caused by the trapping of diffusing electroactive molecules in rugged landscape. Additional advantage of this method is explored for determination of unknown diffusion coefficient through equation: D 1 / ω M 1 = D 2 / ω M 2 , using same electrode in two different media with diffusion coefficient D 1 and D 2 . Finally, experimental results shows the resilience of this novel in-situ EIS method for the determination of h and D in different media. [ABSTRACT FROM AUTHOR]

In advanced packaging technology, the micro bump has become an important means of chip stacking and wafer interconnection. The reliability of micro bumps, which plays an important role in mechanical support, electrical connection, signal transmission and heat dissipation, determines the quality of chip packaging. Surface morphological defects are one of the main factors affecting the reliability of micro bumps, which are closely related to materials and bonding process parameters. In this paper, the electrodeposition process of preparing gold bumps is simulated at the atomic scale using the Kinetic Monte Carlo method. The differences in surface morphology and roughness of the plated layer are studied from a microscopic perspective under different deposition parameters. The results show that the gold micro bumps prepared by electrodeposition have better surface quality under conditions of lower deposition voltage, lower ion concentration and higher plating temperature, which can provide significant guidance for engineering applications. [ABSTRACT FROM AUTHOR]

In advanced packaging technology, the micro bump has become an important means of chip stacking and wafer interconnection. The reliability of micro bumps, which plays an important role in mechanical support, electrical connection, signal transmission and heat dissipation, determines the quality of chip packaging. Surface morphological defects are one of the main factors affecting the reliability of micro bumps, which are closely related to materials and bonding process parameters. In this paper, the electrodeposition process of preparing gold bumps is simulated at the atomic scale using the Kinetic Monte Carlo method. The differences in surface morphology and roughness of the plated layer are studied from a microscopic perspective under different deposition parameters. The results show that the gold micro bumps prepared by electrodeposition have better surface quality under conditions of lower deposition voltage, lower ion concentration and higher plating temperature, which can provide significant guidance for engineering applications.

The purpose of this work is to investigate the optical constants of ZnO films doped by Cu, Al, and Cu-Al nanoparticles. The reflectance and the transmittance spectra measurements were applied for calculating these optical constants in the range of 200–2500 nm. It can be seen that ZnO films doped with Al nanoparticles have a maximum value nanoparticles size of about 23.73 nm. With increasing annealing temperature for all wavelength range, due to the improvement of crystalline structure and hence decreasing defects, the extinction coefficient of films decreased. The theoretical extrapolation of ε1 versus λ2 at low wavelengths values provides the dielectric constant ε∞ and for the ZnO films doped with Cu nanoparticles, it has a maximum value of 4.61. The ZnO films doped by Al nanoparticles have a minimum value of χ c in all energy range. The dissipation factor tan δ of ZnO films doped by Cu nanoparticles especially in high energy has a maximum value. SEL functions in ZnO films doped by Cu nanoparticles have the maximum value. [ABSTRACT FROM AUTHOR]

• Performance optimization of ZnO/PbS solar cells by controlling surface roughness. • The size of ZnO NCs aggregation was tuned by varying binary solvent volume ratio. • ZnO aggregation having surface roughness close to size of PbS QDs performs better. • Enhanced performance is attributed to improved junction interface contact. • This approach of interface engineering can be adopted for other QDs based systems. Effective charge transport through heterojunction interface in Quantum dots (QDs) based solar cells is difficult due to the spherical structure of QDs. Therefore tuning of QDs size for uniform and defect free heterojunction interface becomes very important to get optimum device performance. Here we have optimized the performance of ZnO Nanocrystals (NCs)/lead sulfide (PbS) QDs heterojunction solar cell by controlling the surface roughness of ZnO NCs thin films. The synthesized ZnO NCs aggregation was tuned by varying the binary solvent volume ratio of chloroform and methanol (CF:MeOH), which leads to the different surface roughness. The thin film of ZnO NCs having surface roughness comparable to the size of PbS QDs performs better as compared to those devices having different surface roughness. The optimum device fabricated in an ambient atmosphere with ZnO NCs thin film having surface roughness 4.36 nm, and nanocrystal size 3.32 nm as synthesized with (CF:MeOH) volume ratio of (2:1), shows the highest efficiency of 2.94% among other devices in the same structure due to decreased leakage current and improved junction interface contact between active materials. This work reveals that the controllability of ZnO NCs surface roughness and its correlation with the size of QDs can contribute to further improvement of low cost QDs based solar cells. [ABSTRACT FROM AUTHOR]

• Surface instability in PDMS film in adhesive contact begets self-organized pattern. • Increased RMS roughness in these films engenders selective adsorption of the oil. • Ratio between the pore sizes to oil drop diameter dictates oil adsorption capacity. • Surface columns adsorb oil, of double the weight of the adsorbent. A new, simple, cost effective and facile method of adsorption of oil from oil - water mixture on self-organized patterns formed over a soft thin elastic film has been developed, which is of great ecological importance. Surface corrugations (such as columns, labyrinths and cavities evolved spontaneously due to instability on the surfaces of a thin soft elastic PDMS film in adhesive contact with a contactor) along with the oleophilic nature of the film help in selective adsorption of the oil from the oil-water mixture into the intervening surface spaces. The increase in RMS surface roughness brought about either by increase in adsorbent weight or by formation of a columnar structure (instead of cavities or labyrinths) was found to have a significant incremental effect on the true surface area creation by formation of increased number of oil adsorption sites: leading to higher oil penetration and thus, higher oil adsorption. For 0.3 wt% of adsorbent, adsorption was found to be maximum for columnar structures at 23%, followed by cavities at 15% and minimum with labyrinth at around 12%. The ratio (d p / d d) of the substrate pore size dimension (d p) to the surface oil droplet dimension (d d) in crude oil, motor oil, diesel and petrol were found to be progressively lower and hence the maximum adsorption and penetration in the columnar patterns was recognized in case of crude oil. The different oil morphology on adsorption can be greatly used as a marker to identify different category of oil. The surface columns fabricated by self-organization was found to adsorb double the weight of the adsorbent, and moreover the quantity of the polymeric material required in the present case was much less than that for bulk adsorbents, and also does not involve any additional functionalization or use of any external template material, making this method a very suitable one for selective oil adsorption. [ABSTRACT FROM AUTHOR]

The present study considers finite element analysis of an elastic and elastic-plastic contact between a rigid flat and a real rough surface taking into account the asperities interaction. Numerical modeling and measurement of the normal interfacial stiffness were conducted. Surfaces with different rms roughness values were investigated in the elastic and power-law hardening models to highlight the combined effect of the topography and the strain hardening on the contact characteristics. The influence of the surface roughness on the interaction between neighboring micro-contacts, the residual stress and deformation for the power-law hardening material was analyzed. The obtained results have shown the importance of considering the strain hardening in the modeling of a rough contact especially for rougher surface.

A platinum catalyst undergoes complex deterioration process during its operation as a cathode in a proton exchange membrane fuel cell. By using in situ electrochemical atomic force microscopy (EC-AFM) with super-sharp probes, we quantitatively describe the roughening of platinum thin films during electrochemical cycling to different upper potentials, which simulate critical operation regimes of the proton exchange membrane fuel cell. The comprehensive quantitative analysis of morphology changes obtained using common roughness descriptors such as the root mean square roughness, the correlation length and the roughness exponent is correlated with cyclic voltammetry performed simultaneously. [ABSTRACT FROM AUTHOR]

As an emerging technique for surface smoothing, solution deposition planarization (SDP) has recently drawn more attention on the fabrication of the second generation high temperature superconducting (2G-HTS) tapes. In our work, a number of amorphous oxide layers were deposited on electro-polished or mirror-rolled metallic substrates by chemical solution route. Topography evolution of surface defects on these two types of metallic substrates was thoroughly investigated by atomic force microscopy (AFM). It was showed that root mean square roughness values (at 50 × 50 μm 2 scanning scale) on both rough substrates reduced to ∼5 nm after coating with SDP-layer. The smoothing effect was mainly attributed to decrease of the depth at grain boundary grooving on the electro-polished metallic substrate. On the mirror-rolled metallic substrates, the amplitude and frequency of the height fluctuation perpendicular to the rolling direction were gradually reduced as depositing more numbers of SDP-layer. A high J c value of 4.17 MA cm −2 (at 77 K, s.f. ) was achieved on a full stack of YBCO/CeO 2 /IBAD-MgO/SDP-layer/C276 sample. This study enhanced understanding of the topography evolution on the surface defects covered by the SDP-layer, and demonstrated a low-cost route for fabricating IBAD-MgO based YBCO templates with a simplified architecture. [ABSTRACT FROM AUTHOR]

This study quantified roughness for individual wavebands in the long wavelength range in pavement longitudinal profiles. Particularly, the roughness was related with quantified plausible factors associated with those wavebands. Root Mean Square (RMS) roughness defined under the Power Spectral Density (PSD) profile in the frequency domain was used as a quantified index that can reflect detailed roughness information for a specific waveband. A method to interpret the quantified roughness in terms of the International Roughness Index (IRI) was also developed. It was demonstrated that the RMS roughness evaluated in individual wavebands under the PSD function can be technically interpreted in terms of IRI. Thus, the interpreted IRI could be directly explained by the quantified plausible factors. It was concluded that the demonstrated method can contribute to improved roughness prediction models the Mechanistic-Empirical Pavement Design Guide (MEPDG) with smoothness characteristics in detailed wavelengths underpinnings in future generations of pavement design models. [ABSTRACT FROM AUTHOR]

When composition and crystallographic structure remain constant, film properties mainly depend on microstructure and surface morphology. In this case, the proper modeling of a growing film allows linking the final surface features with the operating conditions at the reactor scale which in turn enables the control of the properties of the final film. In this work, an experimentally supported, coarse-grained, multiscale framework is applied for the modeling of the surface roughness of aluminum thin films processed by chemical vapor deposition from dimethylethylamine alane. The multiscale framework is developed by linking macroscopic transport phenomena based on continuum mechanics models with nanoscale surface events which are simulated stochastically. The model reproduces experimental data successfully, thus validating the method with good statistics. Finally, modeling of surface roughness enables the estimation of the electrical resistivity in good agreement with corresponding measurements. [ABSTRACT FROM AUTHOR]

The present study considers finite element analysis of an elastic and elastic-plastic contact between a rigid flat and a real rough surface taking into account the asperities interaction. Numerical modeling and measurement of the normal interfacial stiffness were conducted. Surfaces with different rms roughness values were investigated in the elastic and power-law hardening models to highlight the combined effect of the topography and the strain hardening on the contact characteristics. The influence of the surface roughness on the interaction between neighboring micro-contacts, the residual stress and deformation for the power-law hardening material was analyzed. The obtained results have shown the importance of considering the strain hardening in the modeling of a rough contact especially for rougher surface. [ABSTRACT FROM AUTHOR]

We report the morphological changes on Ge surfaces upon 50 keV Ar+ and 100 keV Kr+ beam irradiation at 60° angle of incidence. The Ge surfaces having three different amorphous-crystalline (a/c) interfaces achieved by the pre-irradiation of 50 keV Ar+ beam at 0°, 30° and 60° with a constant fluence of 5 × 1016 ions/cm2 were further processed by the same beam at higher fluences viz. 3 × 1017, 5 × 1017, 7 × 1017 and 9 × 1017 ions/cm2 to understand the mechanism of nano-scale surface patterning. The Kr+ beam irradiation was carried out only on three fresh Ge surfaces with ion fluences of 3 × 1017, 5 × 1017 and 9 × 1017 ions/cm2 to compare the influence of projectile mass on surface patterning. Irrespective of the depth of a/c interface, the nanoscale surface patterning was completely missing on Ge surface with Ar+ beam irradiation. However, the surface patterning was evidenced upon Kr+ beam irradiation with similar ion fluences. The wavelength and the amplitude of the ripples were found to increase with increasing ion fluence. In the paper, the mass redistribution at a/c interface, the incompressible solid flow through amorphous layer, the angular distribution of sputtering/backscattering yields and the generation of non-uniform stress across the amorphous layer are discussed, particularly in analogy with low energy experiments, to get better understanding of the mechanism of nanoscale surface patterning by the ion beams. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Introduction: Various works have shown that diamond-like carbon (DLC) coatings are able to improve the cells adhesion on prosthesis material and also cause protection against the physical wear. On the other hand there are reports about the effect of substrate polishing, in evidence of that roughness can enhance cell adhesion. In order to compare and quantify the joint effects of both factors, i.e, polishing and DLC coating, a commonly prosthesis material, the Ti-6Al-4V alloy, was used as raw material for substrates in our studies of macrophage cell adhesion rate on rough and polished samples, coated and uncoated with DLC. Methods: The films were produced by PECVD technique on Ti-6Al-4V substrates and characterized by optical profilometry, scanning electron microscopy and Raman spectroscopy. The amount of cells was measured by particle analysis in IMAGE J software. Cytotoxicity tests were also carried out to infer the biocompatibility of the samples. Results: The results showed that higher the surface roughness of the alloy, higher are the cells fixing on the samples surface, moreover group of samples with DLC favored the cell adhesion more than their respective uncoated groups. The cytotoxity tests confirmed that all samples were biocompatible independently of being polished or coated with DLC. Conclusion: From the observed results, it was found that the rougher substrate coated with DLC showed a higher cell adhesion than the polished samples, either coated or uncoated with the film. It is concluded that the roughness of the Ti-6Al-4V alloy and the DLC coating act complementary to enhance cell adhesion. [ABSTRACT FROM AUTHOR]

We report various SF 6 /Ar plasma textured periodic glass surface morphologies with high transmittance, haze ratio, and root mean square (rms) roughness of ITO:Zr films for amorphous silicon thin film solar cells (a-Si TFSCs). SF 6 /Ar plasma textured glass surface morphologies contain micro- and nano-textured features that help to scatter the light in visible and near infra-red (NIR) wavelength regions. We designed the textured glass surface morphologies with big square craters to smaller pyramids for various glass etching times from 30 to 75 min. Magnetron sputtered ITO:Zr (∼210 nm) films were deposited on textured glass surface morphologies and showed higher transmittance and haze ratio of 88.48% and 77.61%, respectively, in the visible-NIR (400–1100 nm) wavelength region. The sheet resistance and resistivity of ITO:Zr films decreased with the increase of etching time, due to high rms roughness and better step coverage. A passivation AZO (30 nm) layer was added to the ITO:Zr films, due to its better stability against hydrogen plasma exposure. The ITO:Zr/AZO films were employed as a front TCO layer and the current density–voltage (J–V) characteristics of a-Si TFSCs increased by light scattering effect, without any reduction in either the open circuit voltage (V OC ) or the fill factor (FF). Relative to flat glass substrate, J SC and the efficiency of a-Si TFSCs were enhanced by 7.51% and 19.39%, respectively, for textured glass surface morphology. [ABSTRACT FROM AUTHOR]

Highlights: [•] Electrochemical polishing of copper foils at elevated temperature in H3PO4 electrolytes. [•] Copper foils electropolished at 65°C in 2.17M H3PO4 exhibited a lower surface roughness. [•] New prospects for the preparation of copper foils before the growth of high quality graphene layers. [ABSTRACT FROM AUTHOR]

The visible luminescence from Ge nanoparticles and nanocrystallites has generated interest due to the feasibility of tuning band gap by controlling the sizes. Germanium (Ge) quantum dots (QDs) with average diameter ~16 to 8 nm are synthesized by radio frequency magnetron sputtering under different growth conditions. These QDs with narrow size distribution and high density, characterized using atomic force microscopy (AFM) and field emission scanning electron microscopy (FESEM) are obtained under the optimal growth conditions of 400 °C substrate temperature, 100 W radio frequency powers and 10 Sccm Argon flow. The possibility of surface passivation and configuration of these dots are confirmed by elemental energy dispersive X-ray (EDX) analysis. The room temperature strong visible photoluminescence (PL) from such QDs suggests their potential application in optoelectronics. The sample grown at 400 °C in particular, shows three PL peaks at around ~2.95 eV, 3.34 eV and 4.36 eV attributed to the interaction between Ge, GeOx manifesting the possibility of the formation of core-shell structures. A red shift of ~0.11 eV in the PL peak is observed with decreasing substrate temperature. We assert that our easy and economic method is suitable for the large-scale production of Ge QDs useful in optoelectronic devices. [ABSTRACT FROM AUTHOR]

Research on diamond-like carbon (DLC) films has been devoted to find both optimized conditions and characteristics of the deposited films on various substrates. In the present work, we investigate the quality of the DLC films grown on stainless steel substrates using different thickness of the nickel nanoparticle layers on the surface. Nickel nanoparticles were sputtered on the stainless steel substrates at 200 °C by a DC-sputtering system to make a good adherence between DLC coating and steel substrates. Atomic Force Microscopy was used to characterize the surface roughness and distribution function of the nickel nanoparticles on the substrate surface. Diamond like carbon films were deposited on stainless steel substrates coated by nickel using pure acetylene and C2H2/H2 with 15% flow ratio by DC-Plasma Enhanced Chemical Vapor Deposition (PECVD) systems. Microstructural analysis by Raman spectroscopy showed a low intensity ratio ID/IG for DLC films by increasing the Ni layer thickness on the stainless steel substrates. Fourier Transforms Infrared spectroscopy (FTIR) evidenced the peaks attributed to C-H bending and stretching vibration modes in the range of 1300-1700 cm-1 and 2700-3100 cm--1, respectively, in good agreement with the Raman spectroscopy and confirmed the DLC growth in all samples. [ABSTRACT FROM AUTHOR]

This work deals with the effect of surface roughness parameters on the frictional properties of nanowire-based lubrication systems (NBLS) across Cu surfaces with various topographies. The friction coefficient was discussed in the context of surface roughness parameters including the rms height, inter-island separation and a combined roughness parameter related to the pressure experienced by each nanowire. It was concluded that the rms height of asperity should not be lower than the radius of nanoparticles for effective lubrication. In addition, when the inter-island separation is an integer multiple of the nanowire length, nanowires perform as effective lubricants. Furthermore, the friction coefficient increased when the mean pressure experienced by the nanowires increased. The results obtained in this original study offer some interesting insights into the frictional properties of NBLS as a function of surface roughness parameters. This could lead to a great impact on the selection of nanoparticle-based lubricant aimed at reducing wear and energy losses for various applications. [ABSTRACT FROM AUTHOR]

Abstract: (In,Ga)2Se3 thin films were deposited on Mo-coated glass substrates by a conventional MBE system. To control the preferred orientation of Cu(In,Ga)Se2 (CIGS) layers, the deposition temperature dependence T depo of the (In,Ga)2Se3 layer was investigated including observations of both surface morphology and cross-sectional structure, Raman scattering and preferred orientation in the range 50–500°C. γ-phase (In,Ga)2Se3 films exhibited (110) and (300) X-ray diffraction lines with a little or no (006) line contribution for T depo>300°C. It was revealed that a (300) preferred orientation of the (In,Ga)2Se3 layer could promote a (220/204) orientation of subsequently grown CIGS films, which were obtained only at the moderate temperatures of 300–400°C during (In,Ga)2Se3 deposition. [Copyright &y& Elsevier]

• Growth of ripple patterns on Si (1 0 0) for two projectile masses of Ar+ and Kr+. • Higher sputtering yield for Kr+ ions favours higher amplitude of ripples. • Higher penetration range of Ar+ favours the longer wavelength of ripples. • Ripples growth are controlled by ion beam sputtering and solid flow. Control over the dimensions of nanoscale patterns on macroscopic areas of solid surfaces by varying ion beam parameters has been useful in electronic, optic and optoelectronic applications. This work presents a comparative study on projectile's (Ar and Kr) mass-dependent growth of ripples as a function of the incidence angle. Oblique implantation produces ripples between 50°-70° with highest ordering at ∼ 60°. Heavy mass implantation (Kr+) produces higher amplitude of ripples with shorter wavelength as compared to lighter Ar+ ion, and vice versa. Compositional study shows that the broader near surface damage for Ar+ under higher penetration range produces longer ripple wavelength as compared to Kr+. [ABSTRACT FROM AUTHOR]

Abstract: In the field of biomaterials surfaces, the ability of the atomic force microscope (AFM) to access the surface structure at unprecedented spatial (vertical and lateral) resolution, is helping in a better understanding on how topography affects the overall interaction of biological cells with the material surface. Since cells in a wide range of sizes are in contact with the biomaterial surface, a quantification of the surface structure in such a wide range of dimensional scales is needed. With the advent of the AFM, this can be routinely done in the lab. In this work, we show that even when it is clear that such a scale-dependent study is needed, AFM maps of the biomaterial surface taken at different scanning lengths are not completely consistent when they are taken at the same scanning resolution, as it is usually done: AFM images of different scanning areas have different point-to-point physical distances. We show that this effect influences the quantification of the average (R a) and rms (R q) roughness parameters determined at different length scales. This is the first time this inconsistency is reported and should be taken into account when roughness is measured in this way. Since differences will be in general in the range of nanometres, this is especially interesting for those processes involving the interaction of the biomaterial surface with small biocolloids as bacteria, while this effect should not represent any problems for larger animal cells. [Copyright &y& Elsevier]

In order to show that surface area is not always a quantity proportional to the surface roughness, we have constructed simple surfaces consisting of boxes of the same height equally spaced, and rms roughness and surface area have been computed. We have shown how we can get examples of surface configurations for which an increment in the surface roughness corresponds to a decrease in the surface area, although this is observed only for surfaces having similar rms roughness. We have also shown that even in the more intuitive situations where an increase in the surface roughness leads to an increase in the surface area, this increase is not necessarily equivalent. Analogous conclusions have been found when roughness was evaluated through the average roughness. These results could be interesting when analyzing interfacial phenomena such as cell adhesion, especially from a microscopic point of view, where the exact contact area between interacting phases governs these phenomena, and an exact-as-possible approximation to its real value is desirable. Also, the results of this paper could be of interest in various biomedical applications where the modulation of material surface-by-surface roughness may play a significant role. It can be concluded that care should be taken when using roughness parameters as estimators or indicators of the contact area between phases, since the relationship is not always simple. [Copyright &y& Elsevier]

Abstract: Surface roughening of boron -doped Si samples under low energy (0.5 keV/ , 44 and 54, and 1.0 keV/ , 48) bombardment at oblique incidence with and without oxygen flooding was studied with atomic force microscopy (AFM) and secondary ion mass spectrometry (SIMS). The erosion rate, the surface topography and the depth resolution as a function of depth have been measured. Changes in secondary ion yields have been correlated with changes in surface topography. It is found that the surface roughness depends on impact energy and incidence angle without flooding. The roughness decreases with decreasing impact energy. For the same energy (0.5 keV/ ), the wavelength increases slightly with increasing angle of incidence and the roughness increases with increasing angle of incidence. With flooding, the roughness can be efficiently avoided. The best conditions to avoid roughness when analysing ultra shallow profiles with our magnetic sector instrument is 0.5 keV/ , 44 with flooding. A procedure for the depth calibration of the profiles revealed that surface roughness causes an erosion rate change as measured using the shift of the position of the measured B peaks with and without flooding. The consequences of the roughness in terms of depth resolution of the profiles are analysed with and without flooding. Moreover, we show that the value of the Gaussian broadening parameter of the depth resolution function is closely related to the final dispersion of the heights in the crater bottom. [Copyright &y& Elsevier]

Abstract: Effects of mass analyzed low energy O2 + ion implantation in Al thin films on the hardening and microstrucure have been studied by nanoindenting atomic force microscopy (AFM). The fluence range was 1×1017–1×1018 Oatoms/cm2. A maximum increase of hardness about 90% of the implanted samples is observed. Apparently there is no significant variation in the hardness values within the range of ion fluences investigated here. Finally, the surface roughness is found to decrease considerably by oxygen irradiation. [Copyright &y& Elsevier]

Abstract: In this paper, the SIMS beam induced roughness (BIR) in monocrystalline Si in presence of initial surface or bulk defects of nanometric size is studied. We follow the development of the BIR by monitoring the increase of Si2+ and SiO2 + signals during SIMS sputtering. The topography of the crater bottoms is measured at different steps of the evolution of the roughness using an atomic force microscope (AFM). We show that in presence of nanometric sized defects on the surface or in the bulk, the BIR develops far more rapidly than usual. It appears as soon as the crater reaches the defects and, as reported on Si free from any treatment, the same morphology evidencing waves perpendicular to the sputtering beam develops rapidly. This study of the behaviour of the BIR in presence of voluntarily introduced defects allows us to better understand the basic physical phenomena involved in its apparition. [Copyright &y& Elsevier]

To achieve the integration of self-alignment connection between single-mode fiber and rib waveguide in a silicon-on-insulator (SOI) wafer, a three-mask lithography process was used. Micrographs revealed uniform U-grooves and accurate self-alignment between the U-groove and the rib waveguide. An atomic force microscope with an ultrasharp tip was used to directly measure the endface profile of the SOI rib waveguide etched using inductively coupled plasma reactive ion etching (ICPRIE). The rms roughness of the SOI rib waveguide endface was compared with that of a conventional chemical mechanical polishing endface. As an attractive single layer antireflection coating on silicon substrate, HfO2 film reduced the Fresnel reflection losses from 2.55 to 0.022 dB. After depositing HfO2 films onto waveguide endfaces, the rms roughness difference between the two SOI rib waveguides was also investigated. The rms endface roughness was influenced by the highly directional waveguide endface etched by ICPRIE. The results indicated that the three-mask lithography ICPRIE process is easy, cost-effective, and acceptable in a mass production environment. [ABSTRACT FROM PUBLISHER]

The microstructure of BaTiO3 (BTO)/SrTiO3 (STO) superlattice grown on (001) STO substrate by laser molecular beam epitaxy (L-MBE) was investigated. The microstructural parameters of BTO/STO superlattice, such as the total film thickness, superlattice period, surface and interface root-mean-square (rms) roughness were obtained by computer simulation of the small-angle X-ray diffraction spectra. The results show that the interfaces and surface of the superlattice are very smooth; their rms roughness is about 2 A˚. The experimental examination of atomic force microscopy has proved the smoothness of the surface of the superlattice. There exists a little correlation along 〈001〉 direction of the surperlattice. The growth mechanism of the superlattice is discussed. By modified Bragg's law, the total thickness of the superlattice is calculated, and is consistent with that of the simulation of small-angle X-ray reflectivity. [Copyright &y& Elsevier]