Barrier Layer Thickness Research Articles

Interface dynamics in ohmic contact optimization on AlGaN/GaN heterostructure by the formation of TiN

We illustrate a systematic approach to reduce the ohmic contact resistance on AlGaN/GaN heterostructure. We have optimized the ohmic contact resistance by varying the thickness of AlGaN barrier layer, Ti layer, Al/Ti ratio, and temperature. We have observed nonlinear dependency on various process conditions. Careful observations on performed experiments bring out the interface dynamics of the metal and semiconductor layers. We have demonstrated a very low typical contact resistance of 0.06 Ω.mm for AlGaN barrier thickness of 13 nm, Ti/Al/Ni/Au of 12/150/40/50 nm, and annealed at 775 °C. The minimum contact resistance is found to be 0.05 Ω mm when measured across devices. This RC value is appropriate for high power RF applications of AlGaN/GaN based high electron mobility transistors. This value of the contact resistance is the lowest among the values reported on AlGaN/GaN heterostructure using alloyed contacts. A lower thickness AlGaN barrier can help to reduce the thermal budget for achieving low ohmic contact resistance. This is achieved at lower critical thickness for Ti which is dependent on the AlGaN barrier thickness. It is also observed that Ti:Al ratio should be increasingly larger for decreasing thickness of Ti. This trend is observed till 7 nm of Ti.

An Index of Aquiclude Destabilization for Mining-Induced Roof Water Inrush Forecasting: A Case Study

Aquiclude plays a critical role in the occurrence of mining-induced roof water inrush in underground coal mines. This paper proposes an assessment index for the evaluation of aquiclude stability and a threshold value of water inrush from the roof, based on a case study of roof water inrush accidents in Cuimu coal mine, China. The relation between roof water inrush and water level variation in the aquifer, and the characteristics of aquiclude deformation, were studied in this assessment. Using the developed assessment criteria, the likelihood of roof water inrush was categorized into different risk levels, which were followed by a proposal for roof water inrush control measures. The main findings of this study are: a) in Cuimu coal mine, the waterbody in the bed separation between the upper aquifer and the aquiclude directly causes the inrush, and inrush occurs after the water level declines in the aquifer; b) tension-induced horizontal strains of aquiclude can be regarded as the index to evaluate the stability of aquiclude affected by underground coal mining—roof water inrush occurs when the maximum horizontal strain reaches a threshold of 10mm/m—c) based on the critical mining height for aquiclude instability, and the different thicknesses of barrier layers, high-risk zones are identified and inrush controls are proposed.

In-situ removal of thick barrier layer in nanoporous anodic alumina by constant current Re-anodization

A novel method for thick barrier layer removal of nanoporous anodic alumina (NAA) based on a constant current re-anodization (third anodization step) is reported. The barrier layer consists of an alumina layer that prevents electrical contact between the inner pore volume and the aluminium substrate. Several methods have been reported for the removal of such alumina layer. However, none of them is applicable to NAA produced under high anodization voltages, for example with phosphoric acid (H3PO4) electrolyte. Herein, NAA is obtained by two-step anodization of aluminium at a constant voltage of 195 V in a H3PO4 electrolyte. The novelty of this study consists of the combination of a reduction of the barrier layer thickness with a partial chemical etching in a H3PO4 solution followed by a constant current re-anodization step. This opens branchings in the barrier layer that permit a complete removal with a final chemical etching step in H3PO4 solution. The best condition for removing the barrier layer in the constant current re-anodization step is to fix a constant density current of 17.0 μA/cm2. We obtain self-ordered NAA substrates without barrier layer, allowing for the establishment of an electrical contact between the aluminium substrate and the interior of the nanopores. These nanoporous-back metal contact structures can be very important for applications in energy generation, energy storage and optoelectronic devices.

Statistical Characterization of the Observed Cold Wake Induced by North Atlantic Hurricanes

This work quantifies the magnitude, spatial structure, and temporal evolution of the cold wake left by North Atlantic hurricanes. To this end we composited the sea surface temperature anomalies (SSTA) induced by hurricane observations from 2002 to 2018 derived from the international best track archive for climate stewardship (IBTrACS). Cold wake characteristics were distinguished by a set of hurricane and oceanic properties: Hurricane translation speed and intensity, and the characteristics of the upper ocean stratification represented by two barrier layer metrics: Barrier layer thickness (BLT) and barrier layer potential energy (BLPE). The contribution of the above properties to the amplitude of the cold wake was analyzed individually and in combination. The mean magnitude of the hurricane-induced cooling was of 1.7 °C when all hurricanes without any distinction were considered, and the largest cooling was found for slow-moving, strong hurricanes passing over thinner barrier layers, with a cooling above 3.5 °C with respect to pre-storm sea surface temperature (SST) conditions. On average the cold wake needed about 60 days to disappear and experienced a strong decay in the first 20 days, when the magnitude of the cold wake had decreased by 80%. Differences between the cold wakes yielded by mostly infrared and merged infrared and microwave remote sensed SST data were also evaluated, with an overall relative underestimation of the hurricane-induced cooling of about 0.4 °C for infrared-mostly data.

Admittance dependences of the mid-wave infrared barrier structure based on HgCdTe grown by molecular beam epitaxy

The admittance of nBn structures based on HgCdTe grown by molecular beam epitaxy (MBE) on GaAs (013) substrates was studied. The measurements were performed in the temperature range of 10–310 K at the frequencies of 0.5–2000 kHz. The content of CdTe in the absorbing layer was 0.36, and the content in the 210 nm thick barrier layer was 0.84. Equivalent circuits of nBn structure for various temperature and voltage ranges are proposed. The calculated frequency dependences of the admittance are in good agreement with the experimental data. The dependences of the values of the equivalent circuit elements on the area of nBn structure and on temperature are established. It is shown that measurements of the capacitance-voltage characteristic of nBn structure based on MBE HgCdTe in a wide range of conditions allow determining dopant concentration in the absorbing layer. At near room temperatures, features of the voltage dependences of the admittance, which related to the defect level recharge near the heterojunction between the absorbing and barrier layers, were found.

Impact of Satellite-Derived Diffuse Attenuation Coefficient on Upper Ocean Simulation Using High-Resolution Numerical Ocean Model: Case Study for the Bay of Bengal

Impact of satellite-derived shortwave attenuation depth and its spatial variability on the upper ocean dynamics has been studied using a numerical ocean model over the Bay of Bengal. We conducted two simulations, differing in the spatial distribution of shortwave attenuation depth for the period 2014–2015. The control run use a constant attenuation depth of 23 m (the default case for Type-I water) while the experimental run (ER) use spatially varying attenuation depths derived from daily climatology of the diffuse attenuation coefficient (). Simulated parameters like sea surface temperature (SST) and mixed-layer depth (MLD) are sensitive to that limits the penetration of downwelling shortwave radiation into the ocean. It has been found that alters the upper ocean thermodynamics significantly. Validation has been performed using satellite, moored-buoy and profile data, for the year 2015. During spring, the errors in SST in the ER are reduced up to 35% at buoy location. The impact of improving shortwave attenuation depth is found to be maximum in the upper ocean (50–150 m). Error in simulated temperature at 100 m depth is reduced by 15% in the ER. MLD, barrier layer thickness, and the depth of 26 °C isotherm also show significant improvements in the ER.

Effects of recess depths on performance of AlGaN/GaN power MIS-HEMTs on the Si substrates and threshold voltage model of different recess depths for the using HfO2 gate insulator

Three types of E-mode AlGaN/GaN MIS-HEMTs with different barrier depths and conventional HEMT were fabricated on the Si substrates. HfO2 gate insulator with a thickness of 30 nm was grown by plasma enhanced atomic layer deposited (PEALD). Characteristics of the four devices with different recess depths are analyzed. The MIS-HEMT with barrier layer thickness of 3 nm features good comprehensive performance. The threshold voltage (Vth) is 1.8 V, the drain current density is 480 mA/mm and the figure of merit (FOM) is 363 MW/cm2. When the barrier thickness is 0 nm, the Vth is up to 3.7 V. A calculation model of threshold voltage for recessed MIS-HEMTs is proposed. When the barrier layer thickness is 6 nm, the calculated value of Vth was 0.3 V which is in good match with the experimental value of 0.4 V. The proposed model provides guidelines for the AlGaN/GaN MIS-HEMTs designs.

Alkaline Corrosion-Resistant Anodic Aluminum Oxide Formed By Etidronic Acid Anodizing

A newly discovered electrolyte for anodizing aluminum, etidronic acid (CH3C(OH)[PO(OH)2]2), operates at high voltages of more than 200 V, and ordered porous alumina measuring 400-670 nm in cell diameter (interpore distance) can be fabricated via constant voltage anodizing. Because such porous alumina film formed at high voltages possesses a thick barrier layer, etidronic acid anodizing may be useful for corrosion protection of aluminum. Here, we describe the alkaline corrosion-resistant porous alumina formed by high voltage anodizing in an etidronic acid solution, and its hydration behavior in boiling water was investigated. Highly pure aluminum plates (99.999 wt%) were anodized in 0.3 M sulfuric acid, 0.3 M oxalic acid, 0.3 M citric acid, and 0.3 M etidronic acid solutions (293 K) at a constant current density of 30 Am-2 or a constant voltage of 250 V. The anodized specimens were immersed in a 2.5 M NaOH solution (293 K). The nanostructural changes were examined by electrochemical impedance spectroscopy (EIS). The anodized specimens were immersed in boiling water to seal the pores in the porous alumina film. The surface and cross-section of the specimens were characterized by field-emission scanning electron microscopy (FE-SEM) The plateau voltages during anodizing aluminum at a constant current density of 30 Am-2 in sulfuric and etidronic acid solutions exhibited approximately 16 V and 197 V, respectively. As the specimen anodized in sulfuric acid was immersed in a 2.5 M sodium hydroxide solution, H2 gas evolution was observed from the surface at the beginning of immersion, and the amount increased with the immersion time. In contrast, the specimen anodized in etidronic acid did not result in hydrogen gas evolution during immersion until 8 min. Here, the capacitance (Cb ) is inversely proportional to the thickness of the barrier layer. Figure 1 shows the changes in the reciprocal Cb with the immersion time, ti . Complete dissolution of porous alumina formed in etidronic acid takes 15 times longer than dissolution of the alumina formed by sulfuric acid anodizing due to the formation of a thick barrier layer. As the porous alumina formed by etidronic acid anodizing is immersed in boiling water, plate-like hydroxides were formed at the bottom of the pores in the initial immersion stage. The thickness of the hydroxide layer increased with the immersion time, and the nanopores are completely sealed by long-term immersion. Figure 1

The response of ocean parameters to tropical cyclones in the Bay of Bengal

AbstractThe Bay of Bengal (BoB) exhibits notable seasonal variations in tropical cyclone heat potential (TCHP), barrier layer thickness (BLT) and sea‐surface temperature (SST). These parameters also undergo profound changes in the presence of tropical cyclones (TCs). The composite structures of these ocean parameters as a function of the season of TC formation, intensity, and translation speed are unknown and are developed in the present study. Composite structures are examined based on 1,222 instantaneous samples from 83 TCs during 2003–2016 using INCOIS‐GODAS analyses. A BLT of 10–30 m and TCHP of 40–80 kJ/cm2 favours TC intensification in the central BoB. The multivariate regression of BLT and TCHP appears to be better for TC intensity up to 64 knots and is highly underestimated for the stronger TCs (>64 knots). The TC right‐rear sector experiences significant changes in TCHP anomaly (TCHPA) as the intensity increases. The TCHPA ranges ∼10–15, ∼20–25 and ∼25–30 kJ/cm2 when a TC is at Cyclone Storm (CS), Severe Cyclonic Storm (SCS) and Very SCS (VSCS) stages respectively. The maximum TCHPA is generally aligned along the TC track during the post‐monsoon season. Slow‐moving TCs produce maximum TCHPA cooling of ∼20 kJ/cm2 within 250 km storm radius in the rear sector, while it is less and away from the storm centre for normal and fast‐movers. The seasonal changes showed opposite relations between BLT and TCHP from pre‐ to post‐monsoon seasons during the TC intensification. TC‐induced SST cooling is maximum (∼0.5–1.2 °C) in the inner core for the strong (VSCS and above) and slow‐moving TCs. The cooling decreases with an increase in the translation speed and is more pronounced in the pre‐monsoon season. This study provides a baseline to verify and understand the limitations of the models, and also develop a climatological perspective of BoB TCs.

Effects of Salinity Variability on Recent El Niño Events

Ocean salinity variability provides a new way to study the evolution of the the El Niño-Southern Oscillation (ENSO). Comparisons between the salinity variation and related processes responsible for sea surface temperature anomaly (SSTA) were extensively examined for the two strong El Niño (EN) events in 1997/1998 and 2015/2016, and a special EN event in 2014/2015. The results show that the development of EN is significantly correlated with a sea surface salinity anomaly (SSSA) in the tropical western-central Pacific. In the spring of 1997 and 2015 with strong EN events, the western-central equatorial Pacific exhibited significant negative SSSA that propagated eastward to the west of the dateline. The negative SSSA induced increased barrier layer thickness (BLT) which enhanced sea surface temperature (SST) warming in the tropical central Pacific. In contrast, although a negative SSSA occurred during April of the 2014/2015 weak EN event in the western-central equatorial Pacific, this SSSA was mainly confined to between 160° E and 180° E without significant eastward movement, resulting in a weakened BLT thickening process and a weak modulation effect on SST. We also confirm that the surface forcing associated with fresh water flux (FWF: evaporation (E) minus precipitation (P)) plays a prominent role in the surface salinity tendency in the tropical Pacific during EN events. Moreover, the negative FWF anomaly leads a strong negative SSSA by two months. Compared with the two strong ENs, the early negative FWF anomaly in the weak 2014/2015 EN did not present distinct development and eastward propagation and weakened rapidly in the summer of 2015. We demonstrate that change in salinity can modulate the ENSO, and the variation of SSSA and associated physical processes in the tropical western-central Pacific and could be used as an indicator for predicting the development of ENSO.

Characterization of Ba-Introduced Thin Gate Oxide on 4H-SiC

A thickness of Ba-introduced gate oxide was controlled with the oxygen concentration and a barrier layer thickness at a post-deposition annealing. The oxidation rate becomes slower with the low oxygen concentration and the thick barrier layer, and the thin oxide of 12 nm was realized with O2 5% and 9 nm of the barrier layer. This Ba-introduced thin gate oxide resulted in the field effect mobility of 13 cm2/Vs and the interface state density of 2×1011 cm-2eV-1 at 0.25 eV below the conduction band edge of 4H-SiC.

Surface chlorophyll-a variations in the Southeastern Tropical Indian Ocean during various types of the positive Indian Ocean Dipole events

ABSTRACT Surface chlorophyll-a (chl-a) variation in the Southeastern Tropical Indian Ocean (SETIO) shows different patterns in response to the various types of the Indian Ocean Dipole (IOD) events. Thirteen years of remotely sensed surface chl-a data from the Moderate-resolution Imaging Spectroradiometer (MODIS) were used to evaluate interannual surface chl-a variation in the SETIO. During the period of analysis (January 2003-December 2015), there were three canonical positive IOD (pIOD) and four pIOD Modoki events. It is found that the spatial patterns of surface chl-a variation were coherent with the pattern of surface wind anomaly, and the sea surface temperature anomaly (SSTA). During canonical pIOD events, high chl-a concentrations were observed in the vicinity of the Sunda Strait and along the coast of western tip of the Java Island around the Cilacap region. Meanwhile, during pIOD Modoki event, surface chl-a concentration was relatively higher and distributed wider than those observed during canonical pIOD event. The analysis shows that relatively weak upwelling event indicated by a deep isothermal layer depth (ILD) during pIOD Modoki events combined with thin barrier layer thickness (BLT) and deep mixed layer provides a favourable condition for an increase in surface chl-a in the SETIO region. Meanwhile, strong upwelling as indicated by shallow ILD combined with thick BLT and shallow mixed layer prevents surface chl-a to increase during canonical pIOD events.

Decadal Variability of the Barrier Layer and Forcing Mechanism in the Bay of Bengal

AbstractUsing Simple Ocean Data Assimilation data set for 1951–2010, we analyze the decadal variability of barrier layer thickness (BLT) and its forcing mechanisms in the Bay of Bengal (BoB). The decadal variability of BLT shows a close connection with the Pacific Decadal Oscillation (PDO). The PDO‐induced spatial distribution of BLT is similar to its first Empirical Orthogonal Function mode, showing a meridional dipolar pattern. PDO can exert an influence on the decadal variations in the Walker circulation to indirectly modulate decadal variations in BLT. Weakened southwesterly winds over the BoB associated with a positive PDO phase enhance shoreward Ekman transport along the eastern and northern boundary of the BoB and therefore deepen isothermal layer depth, which further induces positive BLT anomalies along the eastern and northern coast of the BoB. On the other hand, the weakened winds decrease oceanic heat loss; meanwhile, the enhanced upwelling driven by positive wind stress curl anomalies shoals the isothermal layer depth and thus decreases the BLT over the southeastern BoB. The opposite is true for the negative PDO phase. Using an ocean mixed layer model, we diagnose the relative contribution of different forcing terms to BLT variations on decadal timescales. It is found that horizontal advection and freshwater flux‐induced entrainment dominate the decadal BLT variability in the northern BoB, whereas heat and freshwater flux‐induced entrainment play a dominant role in the southern BoB.

Performance enhancement of UV quantum well light emitting diode through structure optimization

In this paper, an extensive study is carried out via theoretical simulation to determine the electrical and optical characteristics of AlGaN based multi-quantum well near-ultra violet light emitting diodes (MQW-UV-LED) for the emission wavelength of 353 nm. The structure and characteristics of epitaxial layers used in UV-LEDs play a significant role in the performance of the device. We have studied dependence of device output characteristics on its layer structure and optimized the structure properties to improve the performance of the device. During the optimization process, thickness of quantum well layers, thickness of barrier layers, composition of electron blocking layer (EBL) and composition of barrier layer have been changed to their optimal values. In order to calculate the wavefunction, carrier densities, and discrete energy levels within the quantum well, a 6 × 6 Kohn–Luttinger Hamiltonian has been solved. A final structure with optimized values has been proposed in the end. The optimal values for quantum well thickness and barrier thickness are found to be 3.5 nm and 6 nm respectively. Optimum values from aluminium concentration in EBL and barriers are found to be 40% and 22% respectively. The output characteristics of the final device have been simulated and results are demonstrated. The performance of final device for varying temperature have also been simulated and displayed. The results achieved n this work may be beneficial to the entire opto-electronics community.

On the possibility of faster detection of magnetic flux changes in a single-photon counter by RF SQUID with MoRe–Si(W)–MoRe junction

The nonhysteretic mode of a RF SQUID with a MoRe–Si(W)–MoRe Josephson junction is analyzed in order to detect the states of a single-photon counter based on a superconducting quantum interferometer with a discrete Hamiltonian. The absorption of a photon with 10 GHz frequency brings the counter to the excited level causing tunnelling into the adjacent potential well and a change in the magnetic flux in the interferometer, which can be detected by the SQUID magnetometer. Measurement of a quantum system requires minimization of the back action of the signal read-out channel at the counter, high sensitivity, and speed of the magnetometer. The MoRe–Si(W)–MoRe contacts are optimized for various concentrations of tungsten (W) in silicon (Si) and barrier layer thickness. It is shown that using MoRe–Si(W)–MoRe contacts with a tungsten concentration of approximately 11% for the RF SQUID at excitation frequencies of ∼1 GHz makes it practically an ideal parametric upward frequency shifter with noise determined by the cooled amplifier.

The Influence of Oceanic Barrier Layers on Tropical Cyclone Intensity as Determined through Idealized, Coupled Numerical Simulations

AbstractThe connection relating upper-ocean salinity stratification in the form of oceanic barrier layers to tropical cyclone (TC) intensification is investigated in this study. Previous works disagree on whether ocean salinity is a negligible factor on TC intensification. Relationships derived in many of these studies are based on observations, which can be sparse or incomplete, or uncoupled models, which neglect air–sea feedbacks. Here, idealized ensemble simulations of TCs performed using the Weather Research and Forecasting (WRF) Model coupled to the 3D Price–Weller–Pinkel (PWP) ocean model facilitate examination of the TC–upper-ocean system in a controlled, high-resolution, mesoscale environment. Idealized vertical ocean profiles are modeled after barrier layer profiles of the Amazon–Orinoco river plume region, where barrier layers are defined as vertical salinity gradients between the mixed and isothermal layer depths. Our results reveal that for TCs of category 1 hurricane strength or greater, thick (24–30 m) barrier layers may favor further intensification by 6%–15% when averaging across ensemble members. Conversely, weaker cyclones are hindered by thick barrier layers. Reduced sea surface temperature cooling below the TC inner core is the primary reason for additional intensification. Sensitivity tests of the results to storm translation speed, initial oceanic mixed layer temperature, and atmospheric vertical wind shear provide a more comprehensive analysis. Last, it is shown that the ensemble mean intensity results are similar when using a 3D or 1D version of PWP.

Opto-electronic properties of anodized TiO2 nanotube arrays investigated using electron energy loss spectroscopy

A study of the nanoscale crystallinity of anodized TiO2 nanotubes is reported with the aim of demonstrating its influence on the localized optical and electronic properties of the structure. By employing scanning transmission electron microscopy, coupled with electron energy loss spectroscopy, x-ray diffraction and electron energy filtered jump-ratio imaging to probe changes in the electron near edge fine structure of the Ti L3,2 ionization edge, it is found that nanotubes annealed at 450 °C in air for 3 h crystallize in the anatase polymorph along their walls, with the underlying thick oxide barrier layer being predominantly rutile. An increase in annealing temperature to 600 °C results in the co-existence of anatase and rutile along the nanotube length with the nanotube top and bottom showing crystallization in anatase and rutile, respectively. Valence EELS shows that the localized energy band-gap is inconsistent along the nanotube length, deviating between that typically measured for anatase (3.2 eV) and rutile (3.0 eV). The obtained band-gap of 3.21 eV at the nanotube top and 3.44 eV at nanotube bottom is attributed to the co-existence of anatase and rutile phases even at a low annealing temperature of 450 °C.

43‐2: Optical Characteristics of Curved Flexible Light Sources (FLSs) with Small Radius and Metrology Issues

Planar flexible light sources (FLSs) have a variety of features that give a boost to their applications. In this paper, we studied the effect of curvature radius on optical characteristics of convex FLS. For this purpose the properties of a cylindrical OLED as an FLS were studied theoretically and experimentally. The most fundamental characteristic of a FLS is the total luminous flux, the radiation pattern and the spectrum. Two OLED samples with barrier layer thickness of 100 nm and 150 nm were fabricated and their characteristics were measured at curvature radii of R0=∞ mm (flat), R2=143mm (curved) and R5=56.7 mm (curved). Furthermore, the measurement field contours were calculated for non‐tilted and tilted flat planes, and on inner and outer surfaces of a cylindrical FLS. Finally, the metrology issues of the curved FLS were discussed.

Data assimilation of Soil Moisture and Ocean Salinity (SMOS) observations into the Mercator Ocean operational system: focus on the El Niño 2015 event

Abstract. Monitoring sea surface salinity (SSS) is important for understanding and forecasting the ocean circulation. It is even crucial in the context of the intensification of the water cycle. Until recently, SSS was one of the less observed essential ocean variables. Only sparse in situ observations, mostly closer to 5 m depth than the surface, were available to estimate the SSS. The recent satellite ESA Soil Moisture and Ocean Salinity (SMOS), NASA Aquarius SAC-D and Soil Moisture Active Passive (SMAP) missions have made it possible for the first time to measure SSS from space and can bring a valuable additional constraint to control the model salinity. Nevertheless, satellite SSS still contains some residual biases that must be removed prior to bias correction and data assimilation. One of the major challenges of this study is to estimate the SSS bias and a suitable observation error for the data assimilation system. It was made possible by modifying a 3D-Var bias correction scheme and by using the analysis of the residuals and errors with an adapted statistical technique. This article presents the design and the analysis of an observing system experiment (OSE) conducted with the 0.25∘ resolution Mercator Ocean global analysis and forecasting system during the El Niño 2015/16 event. The SSS data assimilation constrains the model to be closer to the near-surface salinity observations in a coherent way with the other data sets already routinely assimilated in an operational context. This also shows that the overestimation of E–P is corrected by data assimilation through salting in regions where precipitations are higher. Globally, the SMOS SSS assimilation has a positive impact in salinity over the top 30 m. Comparisons to independent salinity data sets show a small but positive impact and corroborate the fact that the impact of SMOS SSS assimilation is larger in the Intertropical Convergence Zone (ITCZ) and South Pacific Convergence Zone (SPCZ) regions. There is little impact on the sea surface temperature (SST) and sea surface height (SSH) error statistics. Nevertheless, the SSH seems to be impacted by the tropical instability wave (TIW) propagation, itself linked to changes in barrier layer thickness (BLT). Finally, this study helped us to progress in the understanding of the biases and errors that can degrade the SMOS SSS data assimilation performance.

Structure and properties of TiSiN/Cu multilayer coatings deposited on Ti6Al4V prepared by arc ion plating

The TiSiN/Cu nano-multilayer coatings were deposited on Ti6Al4V substrate by multi-arc ion plating. The distribution and diffusion of Cu were controlled by the designed thickness of Cu layer and TiSiN barrier layer. Anti-bacterial behaviors and anti-fouling properties of TiSiN/Cu multilayer coatings were investigated. The TiSiN/Cu multilayer coating consists of nano-crystalline TiN and amorphous Si3N4. The metallic copper presents as nanosize clusters. When the copper layer thickness is 97.10 nm, the TiSiN/Cu coating with the maximum hardness 40.39 ± 0.77 GPa has the best antifouling behavior with the reduction rate of 79.36%, 66.21% and 41.37% for the P. triceratium, N. closterium and chlorella, respectively. Meanwhile, the TiSiN/Cu multilayer coatings have an excellent anti-bacterial behavior against Escherichia coli and Bacillus sp.