Small Deposition Rate Research Articles

Convergence of Solutions to a Convective Cahn–Hilliard-Type Equation of the Sixth Order in Case of Small Deposition Rates

Convergence of Solutions to a Convective Cahn–Hilliard-Type Equation of the Sixth Order in Case of Small Deposition Rates

Study on Organic Matter Enrichment and Reservoir Characteristics of Permian Longtan Formation Shale in Southeast Sichuan

The study of reservoir space development characteristics and the geochemical parameters of the Permian Longtan Formation in the southeast of the Sichuan Basin at Well X1 was analyzed by using core observations, optical thin-section observations, Ar-ion polishing, scanning electron microscopy, and nitrogen adsorption tests. Major and trace elements of samples, the V/Cr, U/T, enrichment coefficients EF (Mo) and EF (U), chemical alteration indexes CIA and Sr/Cu, and Mo, P, and other index values of different samples were calculated based on the test of organic geochemical parameters. The depositional environment of the Longtan Formation in the study area was systematically analyzed. The Longtan Formation was in a warm and humid climate during the deposition period. The main body of the sedimentary water was in an oxygen-depleted state, and a portion of it was in an oxidized state with high biological productivity. Therefore, it had a small deposition rate. The clay mineral content and organic matter content in the sample played a major role in controlling the development of reservoir space. The content of clay minerals in the sample was high, and it was mainly chlorite and a mixed layer of illite/smectite. Under a microscope, it was observed that the mixed layer of flake illite/smectite and chlorite aggregate mostly developed interlayer pores or microfractures, which played a positive role in the specific surface area and pore volume of the sample.

Effects of Plasma and Evaporated Atoms on the Spatial Distribution of Coating Film Thickness for Electron Beam-Induced Material Evaporation

This paper investigates the spatial distributions of electron beam-evaporated atoms and electron beam-induced plasma in the coating process. The materials evaporated by electron beams first form vapour and then a little of plasma is generated in the vapour. The spatial distributions of electron beam-induced atoms and plasma play an important role on the coating uniformity of composition and thickness. The radial distribution of coating deposition thickness of electron beam-evaporated atoms predicted by this study agrees with the available experimental data. The predicted distribution of ion density in the electron beam-induced plasma agrees with the available measured data. The results reveal that the normalized coating thicknesses at the divergence angle of 6 and 14 degrees of vapor source, respectively, are 0.8 and 0.2 of these at divergence angle of 0 degree of vapor source for titanium and aluminum evaporated separately. The similar tendency for the decreasing coating thickness with the radial distance is also obtained for the co-evaporation of aluminum, titanium, and copper. High rotation rate of substrate of vapor source leads to the small deposition rate. Most ions in the electron beam-induced plasma are attracted by electrons of the electon beam and are located at the neighbourhood of the beam region. Therefore, the ion and ion-attracted electron densities rapidly decrease with the increasing radial distance from the electron beam.

Influence of precursor dose and residence time on the growth rate and uniformity of vanadium dioxide thin films by atomic layer deposition

The growth of vanadium dioxide (VO2) thin films using tetrakis (ethyl-methyl) amino vanadium (TEMAV) and H2O by atomic layer deposition (ALD) has been investigated as a function of the exposure dose and residence time. A novel multiple pulse mode has been employed to mitigate the small deposition rate brought about by the low vapor pressure of TEMAV. Compared to the conventional ALD cycle with a single pulse of precursor, the use of multiple pulsing with very short pulse time allows lower consumption of precursor, but larger exposure dose and longer residence time on the growth surface, resulting in a higher growth rate for a low volatility precursor, while maintaining a good film uniformity across 4-in. wafers. The Raman analysis and the electrical resistivity modulation of the VO2 thin films show that the films synthesized by the multiple pulse mode is comparable to the films synthesized by the conventional single pulse mode.

Corrosion resistance and in vitro bioactivity of dense and porous titania coatings deposited on 316L SS by spraying method

Titania coatings were deposited on 316L SS by the spraying method. It was found that the hardness, corrosion resistance and in vitro bioactivity of the titania coatings depends strongly on their particle size and the deposition rate. A small particle size and lower deposition rate promote the formation of a flat and more compact coating, which improves the corrosion resistance and hardness. However, a rough and porous structure obtained with a high deposition rate is required for the nucleation and growth of hydroxyapatite. Therefore, hard and corrosion resistant coatings with good bioactive properties can be achieved by the deposition of two layers, firstly depositing a dense layer and then a porous titania layer.

Bipolar HiPIMS for tailoring ion energies in thin film deposition

The effects of a positive pulse following a high-power impulse magnetron sputtering (HiPIMS) pulse are studied using energy-resolved mass spectrometry. This includes exploring the influence of a 200 μs long positive voltage pulse (Urev = 10–150 V) following a typical HiPIMS pulse on the ion-energy distribution function (IEDF) of the various ions. We find that a portion of the Ti+ flux is affected and gains an energy which corresponds to the acceleration over the full potential Urev. The Ar+ IEDF on the other hand illustrates that a large fraction of the accelerated Ar+, gain energies corresponding to only a portion of Urev. The Ti+ IEDFs are consistent with the assumption that practically all the Ti+, that are accelerated during the reverse pulse, originates from a region adjacent to the target, in which the potential is uniformly increased with the applied potential Urev, while much of the Ar+ originates from a region further away from the target over which the potential drops from Urev to a lower potential consistent with the plasma potential achieved without the application of Urev. The deposition rate is only slightly affected and decreases with Urev, reaching ~90% at Urev = 150 V. Both the Ti+ IEDF and the small deposition rate change indicate that the potential increase in the region close to the target is uniform and essentially free of electric fields, with the consequence that the motion of ions inside the region is not much influenced by the application of Urev. In this situation, Ti+ will flow towards the outer boundary of the target-adjacent region, with the momentum gained during the HiPIMS discharge pulse, independently of whether the positive pulse is applied or not. The metal ions that cross the boundary in the direction towards the substrate, and do this during the positive pulse, all gain an energy corresponding to the full positive applied potential Urev.

The semiconducting properties of CdS nanocrystalline thin films prepared by chemical bath deposition. Application to the eosin photodegradation

CdS nanocrystalline thin films were synthesized by chemical bath deposition for different deposition times (10–75 min) and the semiconducting and photo-electrochemical properties were investigated. The results indicate that the deposition rate decreases with the deposition time, due to the depletion of Cd2+ and S2− ions near the glass subtract. The structure is characterized by X-ray diffraction; the films crystallize in a cubic blende structure with (111) as a preferential orientation and the crystallite size varies between 13 and 35 nm. The surface morphology, studied by atomic force microscopy, indicates that the growth process occurs through ion by ion mechanism because of the stability of the complex Cd(NH3)4 (~7), the small deposition rate corroborates this result. The UV visible spectra of the films indicate a high transparency (80%). The transmittance data analysis give a variable forbidden band (2.2–2.4 eV), closely related to the deposition time and agree with the disorder range (230–500 meV). The capacitance–voltage measurement exhibits a linear behavior, characteristic of n type conduction, from which a flat band potential of −0.92 VSCE is determined. The Nyquist plot shows a semicircle assigned to the bulk contribution (=2.5 Ω cm2); the center is located below the real axis (−10°), ascribed to a constant phase element (CPE). A fill factor (FF) of 0.37 and energy conversion of 0.38% are obtained under visible illumination. As application, eosin solution (15 ppm) i oxidized under visible light; the best activity is obtained at pH ~6.3. 80% of eosin disappears after 1 h of exposition and the kinetic obeys to a first order model with a rate constant of 4.5 × 10−2 min−1.

Narrow Gap 맞대기 TIG 용접에서 생산성 향상을 위한 연구

Abstract Adoption of narrow gap welding shall be increased for the butt joint of thick plate, because the deformation and welding cost is reduced by decrease of cross-sectional area. However, sometimes narrow gap causes defects such as lack of fusion since it has small groove angle and narrow groove width. Therefore, GMAW, GTAW and SAWprocess shall be adopted to narrow gap welding with small bead hight and low deposition rate. In this study, Super-TIG welding using C-type strip was applied to semi-narrow gap butt joint in order toincrease the welding productivity. High deposition rate 10kg/hr was obtained by high current 600A without undercut, humping bead and other welding defects. Measuring the mean and standard deviation of the meltingdepth to evaluate the developed processes, the fusion line type was determined by measuring the difference betweenmaximum and minium melting depth. Furthermore, a model on arch fusion line and linear fusion line was suggested in order to prevent LF on groove wall in narrow gap butt welding. Key Words : Narrow gap, Butt welding, TIG welding, Super-TIG welding, Deposition rate, Melting depth, Fusion lineISSN 1225-6153Online ISSN 2287-8955

Cylindric high power impulse magnetron sputtering source and its discharge characteristics

High power impulse magnetron sputtering (HiPIMS) is a popular physical vapor deposition (PVD) technology because of the high ionization of the sputtering materials, large coating density, good adhesion, and other favorable properties. However, this technique suffers some disadvantages such as the small deposition rate induced by the high target potential, the metallic droplets produced by the unstable discharge, and different ionizations for different sputtering materials, thereby hampering wider acceptance by the industry. A cylindric HiPIMS source in which the discharge is restricted in the cylinder is described in this paper. By using this source, coatings can be deposited with 100% ions without metallic droplets arising from the unstable discharge, and the unionized sputtered atoms cannot be extracted by the extraction grid with negative potential. Electron oscillation and repetitive sputtering of the unionized atoms occur in the cylinder to enhance collision and ionization. Due to the enlarged discharge area by the cylinder internal surface comparing with the area of the ion outlet (end face of the cylinder), the sputtering ions converge from the inwall to the center of the cylinder target and form an enhanced flow to spray out from the source, which will improve the deposition rate. The structure and discharge characteristics of the novel HiPIMS source are investigated by simulation and experiments. Our results indicate that 8 magnets can provide the reasonable magnetic field and the highest target utilization rate. The distributions of electrons and ions in the target each consist of 8 petals in the optimized magnetic structure, and the highest plasma density happens near the target, which is above 1.31017 m-3. The discharge characteristics confirm that the cylindric sputtering source can be operated under HiPIMS conditions and the evolution of the target currents with target voltage exhibits I-V characteristics typical of HiPIMS. An obvious pre-ionization is observed on the discharge glow and discharge current curves when the extra direct current (DC) is added. The racetrack area is about 60.0% of the target surface. The ion current curves are similar to those of the target currents, but a 40 s delay and about one-tenth current value are observed compared with the target currents. The sputtering is improved by the extra DC, inducing the increased metallic ions and the opposite evolution of gas ions. The results suggest that the cylindric sputtering source can be effectively used to conduct HiPIMS and is a novel way to improve and promote the application of HiPIMS.

Surface structure of yttrium-modified ceria catalysts and reaction pathways from ethanol to propene

The additive effect of 31 metals on activity of ceria catalysts was studied for the conversion of ethanol to propene. Yttrium gave the best results and the propene yield showed a volcano-shaped dependence on the Y amount, being maximized at 20atom% Y to that of Ce. The catalyst was stable due to very small carbon deposition rate which was approximately 1/100 of that on the parent CeO2 catalyst. The water addition increased the propene yield to 30%, decreased the ethene yield to 37%, and did not change the durability. The physicochemical characterization of the Y/CeO2 catalysts indicated that the surface of active catalysts was covered with a solid solution of CeO2 and Y2O3. Pulse experiments of various candidate compounds suggested that the reaction pathways were ethanol→acetaldehyde→ethyl acetate→acetic acid→acetone→2-propanol→propene through Tishchenko reaction, ketonization, and Meerwein–Ponndorf–Verley reduction.

Observations and Mechanism of CaSO4Fouling on Hydrophobic Surfaces

Pool boiling of CaSO4 solution on prepared microscale and nanoscale hydrophobic titania–fluoroalkylsilane (TiO2–FPS) composite coatings on polished AISI304 stainless steel (SS) substrates was carried out to evaluate the antifouling behavior of these surfaces. Lower fouling resistance and looser, slender, and larger CaSO4 crystals on hydrophobic TiO2–FPS coatings were observed compared to those on the TiO2 coatings and SS surfaces. The colloidal interaction energies between crystalline particles and coated surfaces were analyzed by using the extended Dejaguin– Landau–Verwey–Overbeek (XDLVO) theories to explore the possible mechanism of inhibition of fouling. The results of the XDLVO analyses generally agree to the experimental observations. The Lewis acid–base component contributes most of the total XDLVO interaction energy. Low surface free energy and electron donor component of heat transfer surface lead to a low fouling resistance and a small initial deposition rate of CaSO4 fouling. On the basis of the...

Non-equilibrium Phase Diagram for a Model with Coalescence, Evaporation and Deposition

We study a d-dimensional lattice model of diffusing coalescing massive particles, with two parameters controlling deposition and evaporation of monomers. The unique stationary distribution for the system exhibits a phase transition in all dimensions d greater or equal to one between a growing phase, in which the expected mass is infinite at each site, and an exponential phase in which the expected mass is finite. We establish rigorous upper and lower bounds on the critical curve describing the phase transition for this system, and some asymptotics for large or small deposition rates.

Governing processes for reactive nitrogen compounds in the European atmosphere

Abstract. Reactive nitrogen (Nr) compounds have different fates in the atmosphere due to differences in the governing processes of physical transport, deposition and chemical transformation. Nr compounds addressed here include reduced nitrogen (NHx: ammonia (NH3) and its reaction product ammonium (NH4+)), oxidized nitrogen (NOy: nitrogen monoxide (NO) + nitrogen dioxide (NO2) and their reaction products) as well as organic nitrogen compounds (organic N). Pollution abatement strategies need to take into account the differences in the governing processes of these compounds when assessing their impact on ecosystem services, biodiversity, human health and climate. NOx (NO + NO2) emitted from traffic affects human health in urban areas where the presence of buildings increases the residence time in streets. In urban areas this leads to enhanced exposure of the population to NOx concentrations. NOx emissions generally have little impact on nearby ecosystems because of the small dry deposition rates of NOx. These compounds need to be converted into nitric acid (HNO3) before removal through deposition is efficient. HNO3 sticks quickly to any surface and is thereby either dry deposited or incorporated into aerosols as nitrate (NO3−). In contrast to NOx compounds, NH3 has potentially high impacts on ecosystems near the main agricultural sources of NH3 because of its large ground-level concentrations along with large dry deposition rates. Aerosol phase NH4+ and NO3− contribute significantly to background PM2.5 and PM10 (mass of aerosols with an aerodynamic diameter of less than 2.5 and 10 μm, respectively) with an impact on radiation balance as well as potentially on human health. Little is known quantitatively and qualitatively about organic N in the atmosphere, other than that it contributes a significant fraction of wet-deposited N, and is present in both gaseous and particulate forms. Further studies are needed to characterise the sources, air chemistry and removal rates of organic N emissions.

Aerosol and precipitation chemistry measurements in a remote site in Central Amazonia: the role of biogenic contribution

Abstract. In this analysis a 3.5 years data set of aerosol and precipitation chemistry, obtained in a remote site in Central Amazonia (Balbina, (1°55' S, 59°29' W, 174 m a.s.l.), about 200 km north of Manaus) is discussed. Aerosols were sampled using stacked filter units (SFU), which separate fine (d < 2.5 μm) and coarse mode (2.5 μm < d < 10.0 μm) aerosol particles. Filters were analyzed for particulate mass (PM), Equivalent Black Carbon (BCE) and elemental composition by Particle Induced X-Ray Emission (PIXE). Rainwater samples were collected using a wet-only sampler and samples were analyzed for pH and ionic composition, which was determined using ionic chromatography (IC). Natural sources dominated the aerosol mass during the wet season, when it was predominantly of natural biogenic origin mostly in the coarse mode, which comprised up to 81% of PM10. Biogenic aerosol from both primary emissions and secondary organic aerosol dominates the fine mode in the wet season, with very low concentrations (average 2.2 μg m-3). Soil dust was responsible for a minor fraction of the aerosol mass (less than 17%). Sudden increases in the concentration of elements as Al, Ti and Fe were also observed, both in fine and coarse mode (mostly during the April-may months), which we attribute to episodes of Saharan dust transport. During the dry periods, a significant contribution to the fine aerosols loading was observed, due to the large-scale transport of smoke from biomass burning in other portions of the Amazon basin. This contribution is associated with the enhancement of the concentration of S, K, Zn and BCE. Chlorine, which is commonly associated to sea salt and also to biomass burning emissions, presented higher concentration not only during the dry season but also for the April–June months, due to the establishment of more favorable meteorological conditions to the transport of Atlantic air masses to Central Amazonia. The chemical composition of rainwater was similar to those ones observed in other remote sites in tropical forests. The volume-weighted mean (VWM) pH was 4.90. The most important contribution to acidity was from weak organic acids. The organic acidity was predominantly associated with the presence of acetic acid instead of formic acid, which is more often observed in pristine tropical areas. Wet deposition rates for major species did not differ significantly between dry and wet season, except for NH4+, citrate and acetate, which had smaller deposition rates during dry season. While biomass burning emissions were clearly identified in the aerosol component, it did not present a clear signature in rainwater. The biogenic component and the long-range transport of sea salt were observed both in aerosols and rainwater composition. The results shown here indicate that in Central Amazonia it is still possible to observe quite pristine atmospheric conditions, relatively free of anthropogenic influences.

Modeling SiH4/O2/Ar Inductively Coupled Plasmas Used for Filling of Microtrenches in Shallow Trench Isolation (STI)

AbstractModeling results are presented to gain a better insight in the properties of a SiH4/O2/Ar inductively coupled plasma (ICP) and how it interacts with a silicon substrate (wafer), as applied in the microelectronics industry for the fabrication of electronic devices. The SiH4/O2/Ar ICP is used for the filling of microtrenches with isolating material (SiO2), as applied in shallow trench isolation (STI). In this article, a detailed reaction set that describes the plasma chemistry of SiH4/O2/Ar discharges as well as surface processes, such as sputtering, oxidation, and deposition, is presented. Results are presented on the plasma properties during the plasma enhanced chemical vapor deposition process (PECVD) for different gas ratios, as well as on the shape of the filled trenches and the surface compositions of the deposited layers. For the operating conditions under study it is found that the most important species accounting for deposition are SiH2, SiH3O, SiH3 and SiH2O, while ${\rm SiH}_{{\rm 2}}^{{\rm + }} $, ${\rm SiH}_{{\rm 3}}^{{\rm + }} $, ${\rm O}_{2}^{ + } $ and Ar+ are the dominant species for sputtering of the surface. By diluting the precursor gas (SiH4) in the mixture, the deposition rate versus sputtering rate can be controlled for a desired trench filling process. From the calculation results it is clear that a high deposition rate will result in undesired void formation during the trench filling, while a small deposition rate will result in undesired trench bottom and mask damage by sputtering. By varying the SiH4/O2 ratio, the chemical composition of the deposited layer will be influenced. However, even at the highest SiH4/O2 ratio investigated (i.e., 3.2:1; low oxygen content), the bulk deposited layer consists mainly of SiO2, suggesting that low‐volatile silane species deposit first and subsequently become oxidized instead of being oxidized first in the plasma before deposition. Finally, it was found that the top surface of the deposited layer contained less oxygen due to preferential sputtering of O atoms, making the top layer more Si‐rich. However, this effect is negligible at a SiH4/O2 ratio of 2:1 or lower. magnified image

On a Higher Order Convective Cahn--Hilliard-Type Equation

A higher order convective Cahn--Hilliard-type equation that describes the faceting of a growing surface is considered with periodic boundary conditions. By using a Galerkin approach, the existence of weak solutions to this sixth order partial differential equation is established in $L^2(0,T;\dot{H}^3_{per})$. Additionally, stronger regularity results are derived. These are used to prove uniqueness of the solutions. Furthermore a numerical study shows that the transition from coarsening to roughening leads to multidomain-wall stationary and traveling states in a small deposition rate regime and to chaotic surfaces for increased rates. A characteristic length scale decreases logarithmically with increasing deposition rate.

Preparation and Characterization of ZnO: In Transparent Conductor by Low Cost Dip Coating Technique

Transparent conducting oxide (TCO) based on indium doped zinc oxide films in the nano scale were successfully prepared using combination between dip coating and thermal decomposition process. Structural investigations confirm the polycrystalline ZnO hexagonal wurtzite phase grown along the c-axis with nano crystallite size about 10 nm. Morphology investigation shows that ZnO films consist of fine grains of average size 40 nm. This indicates that each grain contains several crystallites with different orientations. Cross sectional image presents good adhesion of the films with the substrate and the film thickness has been determined. Compositional analysis detects the indium content in the host ZnO matrix, the In/Zn ratio is close to the calculated concentration ratios of the precursor. The optical transmittance shows that the films are transparent in the UV and VIS-IR spectral region and interference fringes were observed to be thickness dependent. Preparation parameters were investigated and optimized such as dipping rate, number of deposition cycles, precursor concentration, annealing process and In/Zn ratio. Optimization process was investigated for low resistivity, high optical spectral window transmission and easy preparation process. Dipping rate in the range 2 - 38 mm/s is the most suitable range for good film quality while dipping rate range 30 - 38 mm/s produces thicker films in lower deposition cycles. The higher dipping rate produces films with lower transparency (milky films) while the small deposition rate rate requires large number of deposition cycles in order to increase the thickness. Besides, the higher dipping rate reflects lower resistivity of the deposited films. Precursor molar concentration was observed to have an essential effect on the film thickness, film quality and transparency. Lower precursor concentration requires also large number of deposition cycles for thickening the films. The higher concentration results also milky films (high scattering process by powder film). Precursor concentrations in the range 0.7 - 0.9 mol/liter were found to be the optimal for better quality and for faster deposition process. The resistivity of the films has been reduced from the range 1.5 - 2.5 kW?cm to the range 100 - 400 W.cm as the molar concentration reaches the range 0.07 - 0.09 mol/liter. The resistivity of films increases from 330 to 1686 .cm as the decomposition temperature increases from 200C to 350C. Annealing at 450C process after completing the decomposition at 200?C results the lowest resistivity with annealing time in the range 1.5 - 2 h. In/Zn percentage in the range 1.5% - 5% produces the lowest electrical resistivity. The absorption edge of the deposited films was observed to be critical affected by the preparation parameters. The band gap change was discussed through the degenerate semiconductors as well as nanostructured semiconducting materials of the energy gap confinement effect. Deposition of TCO based on ZnO:In was optimized depending on all deposition parameters forwide area, the lower cost and good performance TCO films.

Chemistry of thin film formation and stability during praseodymium oxide deposition on Si(111) under oxygen-deficient conditions

The growth of thin praseodymium oxide films on silicon (111) using small deposition rates under oxygen-deficient conditions was investigated in the range from submonolayer up to six monolayers coverage by transmission electron microscopy (TEM) and photoemission spectroscopy (PES). A detailed analysis of the silicon 2p and oxygen 1 s core level and valence band spectra reveals chemical reactions between deposited species, substrate, and the growing film. Silicate, silicide and oxide species are coexisting over the entire range of coverages investigated. Cross sectional TEM shows silicide inclusions extending from the surface several nanometers into the substrate and affecting the substrate band bending at the interface. The reactivity of the praseodymia overlayer leads to reactions in the as-deposited film even at room temperature and render it unstable. The article aims at providing a coherent picture of the chemistry proceeding during interface formation and film growth at low rates of deposition (0.06 nm/min). The results will be discussed in comparison to studies using higher rates, emphasizing the possibility of growth rate dependent reactions between substrate and deposited material and, consequently, distinctly different film compositions and structures for different rates of deposition.

Growth of Nano Size Grains in CuInSe<SUB>2</SUB> Thin Films Using E-Beam Deposition Technique

Crystalline defects, such as the density of voids, grain boundaries and dislocations in copper based ternary/multinary semiconducting compounds/alloys such as CulnSe2 and Culn(x)Ga(1-x)Se2 absorber layers depend on the fabrication conditions and determine to a large extent the efficiency of photo-voltaic devices. The material properties, however, can be improved significantly by using the optimized deposition conditions. This paper reports the results of studies carried out on growth and characterisation of CulnSe2 thin films. Coatings of thickness less than one micron were grown using an electron-beam evaporation technique onto glass slides at various substrate temperatures. The structure, surface morphology and electro-optical properties of the films have been investigated using a number of analytical techniques. The effects of the substrate temperature deposition rate, deposition time and type of the target material (a loose powder and single crystal) on the properties of the films have also been examined. In the as-grown films, X-ray diffraction (XRD) analysis revealed a strong preferred orientation with the (112) plane parallel to the substrate. Results from energy dispersive analysis with X-rays (EDAX) indicated a deficiency of selenium and/or copper in some of the samples, otherwise the composition was comparable with the starting polycrystalline material. Scanning electron micrographs showed almost no grains in the films prepared at deposition temperature less than 150 degrees C with small deposition rate of 10 angstroms/sec. However, a nano-scale grain structure (approximately 60-80 nm) was observed in the films grown at elevated temperatures (> or = 200 degrees C) with larger deposition rate of 20 angstroms/sec. The values of the crystallite size calculated from the profile of the main (112) peak using Scherrer formula were in the range of 10-20 nm. Electrical measurements revealed both n- and p-type conductivities with surface resistivity values in the range of 10(-1) to 10(4) omega-cm.

Structure and mechanical properties of CrN/TiN multilayer coatings prepared by a combined HIPIMS/UBMS deposition technique

CrN and TiN coatings are known for their high hardness and good wear resistance. The structure and the mechanical properties of such coatings can be improved by increasing the ion bombardment during film growth. As high power impulse magnetron sputtering (HIPIMS) is known to allow high ion densities in the plasma, with a small deposition rate, we study the structure and mechanical properties of CrN/TiN multilayer coatings deposited by combining HIPIMS with conventional unbalanced magnetron sputtering (UBMS). Our results demonstrate that the microstructure of TiN coatings prepared by UBMS changes from dense columnar to open voided if a one fold substrate rotation is used where the films periodically leave and enter the plasma region in front of the target. Hence, also the hardness decreases from ~ 28 to 12 GPa if a one fold substrate rotation is used. This drawback can be overcome if the coatings are prepared by HIPIMS, resulting in hardness values of ~ 39 and 34 GPa without and with a one fold substrate rotation, respectively. Recently, we reported a corresponding behaviour of CrN coatings. In a multilayer arrangement of TiN and CrN, where the TiN layers are prepared by UBMS and the CrN layers are prepared by HIPIMS the hardness with around 26 GPa is also much higher as compared to 11 GPa of the TiN single layer deposited by UBMS. Hence, HIPIMS also influences the plasma conditions in front of the cathode operated by UBMS.