Resistivity Of Thin Films Research Articles

Influence of Nb and Ta on the corrosion and mechanical properties of CrYN coatings

Barrier coatings are applied to many machine components that are exposed to aggressive/harsh service conditions to prevent corrosion, oxidation, and wear at high temperatures. These coatings are widely used to protect structural components of gas/steam turbines in the energy and aerospace industries against aggressive operating conditions. In this study, Nb and Ta-doped CrYN films were deposited onto 316L stainless steel (SS) using the CFUBMS (Closed Field Unbalanced Magnetron Sputtering) technique. Then, the corrosion resistance, and structural and mechanical properties of the CrYN:Nb/Ta thin films were investigated. SEM, XPS, EDS, nanoindentation and potentiostat tester were used to determine the structural, mechanical and corrosion properties of the thin films, respectively. The highest hardness was found to be 21.4 GPa for CrYN:Nb films and 18.2 GPa for CrYN:Ta films. The results show that the coated specimens (lowest Icorr value 4 nA obtained in all tests) have higher corrosion resistance than the uncoated specimens (substrate Icorr value 1826 nA). In addition, it has been observed that the corrosion resistance of Ta-doped CrYN thin films is somewhat better than the niobium-doped thin films.

A Noncontact Method for Estimating Thin Metal Film Adhesion Strength Through Current-Induced Void Growth

Abstract Studies have reported that the electromigration-induced void growth velocity in metal thin films is inversely related to the adhesion strength of the metal thin film with the base and passivation layers. It was also observed that the contribution of interface adhesion strength to electromigration resistance decreases with an increase in temperature. In this study, an expression is derived for the diffusive void growth velocity induced by electromigration from a generalized thermodynamically consistent continuum-based theory for reaction–diffusion driven solid-state interface evolution. This relation captures the effect of adhesion with the base and passivation layers on electromigration resistance of thin metal films. Electromigration experiments were carried out at elevated temperatures and high current density to induce voiding in thin Cu metal film deposited on a base layer of TiN and passivated with TiN or SiNx. The degradation of interface adhesion strength with temperature is modeled using an Andrade-type of relationship. The void growth rates characterized in these experiments are combined with the expression for void growth rate to estimate the interface adhesion strength for the Cu–TiN and Cu–SiNx interfaces. The methodology for estimating the adhesion strength of the metal-passivation layer interface is validated through comparison with interface adhesion strengths from mechanical de-adhesion tests reported in the literature.

Microstructure evolution and mechanical properties of refractory molybdenum-tungsten nitride coatings

This study focused on the microstructure and the mechanical properties of MoWN coatings fabricated by radio frequency reactive co-sputtering technique. The modulation of input power, which was kept at 150 W for Mo and adjusted from 25 to 125 W for W target, was manipulated. The Ar/N2 inlet gas flow and the background temperature were set at 12/8 sccm/sccm and 350 °C, respectively. The MoWN possessed a multiphase polycrystalline structure featured with Mo(110), MoN2(200), B1-MoN(111) and δ-WN(100) phases. With the increase of W input power, the content of W rose from 4.1 to 24.2 at. %, and a gradual growth of the δ-WN(100) phase was observed. The 150/100 W/W deposited MoWN coating possessed 20.1 at. % W and was dominated by δ-WN(100) phase. From TEM analysis, the longer and wider nano columnar WN(100) grains could be confirmed. The growth of δ-WN(100) phase elevated the compressive residual stress in MoWN films from −4.25 to −7.18 GPa and enhanced the hardness of coatings from 19.7 to 25.7 GPa. This phenomenon also improved the wear resistance of thin film. The wear track maintained smooth and intact after a tribological test of 100 m wear length for MoWN films. Both mechanical and tribological properties were significantly improved, as compared to the MoN film. This could be attributed to the addition of W, which caused the phase transformation and competition between B1-MoN(111) and δ-WN(100) phases. The 150/100 W/W manufactured MoWN exhibited a highest hardness of 25.7 GPa and showed a superior anti-wear behavior with least damage on wear track.

Preparation and photoaging resistance of single-walled carbon nanotubes transparent conductive thin films for electrostatic dust removal of photovoltaic panels

A single-walled carbon nanotubes transparent conductive film for electrostatic dust removal of photovoltaic panels was prepared by a rod coating method and subjected to xenon lamp aging experiments at different irradiance (300 W/m2, 150 W/m2, 50 W/m2, 2000 h) to investigate the photoaging resistance of the film. After aging, the light transmittance decreased from 91.34% to a minimum of 90.39%, the sheet resistance increased from 0.325 * 105 Ω/□ to a maximum of 4.753 * 105 Ω/□, the surface energy decreased, and the adhesive strength of the film at an irradiance of 300 W/m2 decreased from a class 5B to a class 4B. The film was used as the surface material of photovoltaic panels and was subjected to electrostatic dust removal experiments, which showed that the final dust removal rate of different aging types of films was between 97.5% and 98.5%, the power generation efficiency of photovoltaic panels can reach 93.5%− 97.8% of that of ordinary photovoltaic panels in the dust-free state on the surface, and excellent application results are achieved. The results of the study are conducive to expanding the application scenarios of single-walled carbon nanotubes transparent conductive films from indoor or air-isolated areas to outdoor ones.

Offset Voltage Reduction in Two-Stage Folded-Cascode Operational Amplifier Using High-Precision Source Degeneration

The demand for CMOS precision operational amplifiers for critical applications has continuously increased over time due to higher accuracy and sensitivity requirements. Trimming or chopper architectures are advanced solutions that reduce the offset voltage and improve the circuit’s parameters, but the complexity and the increased chip die size are serious downsides. An efficient solution is a source degeneration configuration to control the transistor’s current-mirror transconductance, which impacts the offset voltage, with cost savings and a die area reduction also obtained. This paper focuses on designing and implementing such an approach in a two-stage folded-cascode operational amplifier. State-of-the-art thin-film resistors that use silicon–chromium as the metallic alloy were implemented to reduce mismatch variations between these passive components. Distinct methods that control the offset voltage parameter are also discussed and established. A comparison between the offset voltage standard deviation obtained using different types of resistors and that achieved with the innovative high-precision resistors was also carried out. The source degeneration’s impact on the common-mode rejection ratio, power supply rejection ratio, bandwidth and phase margin was also analyzed, and a comparison between the proposed design and the classical one was performed. The process variation’s influence on the circuit functionality was studied. A pre-layout ±1.273 mV maximum offset voltage at T = 27 °C was achieved using vector/array notations for the amplifier with the best overall performance. Post-layout simulations that included parasitic effects were performed, with a ±1.254 mV maximum offset voltage reached at room temperature.

Humidity induced resistive switching and negative differential resistance in α-Fe2O3 porous thin films

Humidity induced resistive switching and negative differential resistance in α-Fe2O3 porous thin films

Advanced Process Monitoring Through Fault Detection and Classification for the Process Development of Tantalum Nitride Thin-Film Resistors

This paper discusses the optimization of an advanced process monitoring scheme with interdicting fault detection and classification (FDC) capabilities that improved the control over the process development of Tantalum Nitride thin film resistors (TaN TFR). Its implementation in a high-volume manufacturing environment resulted in a reduction of misprocessed wafers, shorter equipment downtime, higher throughput, enhanced process visibility, and yield improvement. Along with optimizing FDC capabilities, implementing a short loop sampling plan reduced the turnaround time for early electrical characterization by a factor of four; this allowed for timely inline adjustments within the fabrication process to tighten the statistical process control (SPC) over the distribution of the process control monitor (PCM) TaN resistor value and improve thin film uniformity.

Effect of stiff substrates on enhancing the fracture resistance of Barium Titanate thin films

Damage tolerance of a thin film attached to a substrate is dependent on several parameters such as film thickness, film orientation, residual stresses, nature of interfaces, microstructure and defects present. Here we study the fracture resistance and crack growth trajectory in BaTiO3 thin films attached to elasticially stiff substrates using micromechanical experiments and finite element modeling. Microcantilever fracture tests are carried out on bi-layered systems of BaTiO3 film on Pt-Si and SrTiO3 substrates to study the effect of interfaces, texture and elastic mismatch on fracture toughness. The substrates in the bi-layers are chosen to force the crack to experience a shielding effect in terms of a decrease in the crack driving force. Experiments revealed an unexpectedly large increase in fracture toughness when the crack tip is closer to a stiffer substrate, qualitatively matching the predictions from the numerical model. The bi-layered films attached to the substrate showed 125% (on Pt-Si) and 160% (on SrTiO3) increase in fracture toughness compared to the free-standing films, for the first time, revealing the significant effect of elastic modulus of the substrate on improving the fracture resistance at such micrometer length scales.

Magnetic domain structure and magneto-transport properties of laser ablated Co40Fe40B20 thin films

We report the magnetic domain structure, and electrical and magnetoresistance properties of laser ablated Co40Fe40B20 (CoFeB) (6 to 36 nm) thin films deposited on SiO2 / Si(001) substrates. Magnetic force microscopy performed on annealed CoFeB thin films revealed larger magnetic domains, which are formed due to strong exchange coupling between the grains. The temperature-dependent sheet resistance of as-deposited thin films revealed that the observed non-metallic behavior is due to intragrain-tunneling and SiO2 inclusions in the amorphous matrix. The metallic behavior of annealed CoFeB thin films is due to electron scattering from grain boundaries and granularity correlated to the formation of nano-crystallites. Thickness and field-dependent magneto-transport studies show higher magnetoresistance values for thinner annealed CoFeB films due to more scattering events upon crystallization, which is consistent with the granular nature of the annealed thin films.

Solution processed multi-layered thin films of Ge20Sb5S75 and Ge20Sb5Se75 chalcogenide glasses

Solution processed non-toxic Ge20Sb5Se75 chalcogenide glass thin films were deposited using spin-coating method from n-propylamine—methanol solvent mixture in specular optical quality. Optical properties, composition, structure, and chemical resistance were studied in dependence on the annealing temperature. Significant increase of refractive index and chemical resistance caused by thermoinduced structural polymerization and release of organic residua were observed. The high chemical resistance of hard-baked thin films allowed repeated direct depositions by spin-coating, increasing total thickness. Multilayered thin films of amorphous Ge20Sb5Se75 and Ge20Sb5S75 were also successfully prepared by direct deposition for the first time. Solution based deposition of non-toxic Ge20Sb5Se75 thin films in specular optical quality significantly widens the applicability of solution processed chalcogenide glass thin films. Moreover, solution based direct deposition of different glasses on hard-baked thin films opens the way to simple and cost-effective preparation of more sophisticated optical elements (e.g. beam splitters, photonic mirrors).

Annealing-induced changes in wear resistance and nanomechanical properties of CuZr metallic glass thin films

Over recent years, metallic glass thin films (MGTFs) have found extensive applications in advanced micro-engineering systems. Consequently, there is a need to thoroughly assess the nanomechanical and tribological behaviors of MGTFs to optimize the design of efficient components. In this study, we employed the nanoindentation technique in various modes to investigate the elastic heterogeneity, tribological response, and mechanical properties of CuZr amorphous films. Before conducting the mechanical tests, annealing treatments at 500 K and 600 K were performed to create samples with different stored energies. The thermal history analysis revealed that the annealing process reduced the stored energy in the microstructure. Furthermore, the pre-annealing treatment resulted in increased hardness and Young’s modulus of the thin films. Additionally, higher annealing temperatures significantly improved the wear resistance of the MGTFs. Observing the serration dynamics in the scratching test, we noticed that the annealing treatment induced larger shear bands on the wear track side. Moreover, the increase in annealing temperature led to a reduction in elastic heterogeneity, which was consistent with the enthalpy relaxation values in the samples. This suggests that the annealing temperature enhanced the densely packed atomic structure, leading to the stabilization of the thin films.

Improvement structure and electrical properties of ITO thin films by annealing treatment

In this paper present, the improvement of ITO thin films properties by thermal annealing treatment by various temperature. The process for this investigation various temperature 100–500 °C under nitrogen environment, control time for 23 mins. The films crystallization improves after annealing process by XRD results show strong peak after post-annealing and resistivity of thin films shows significant reduced from 1996 to 706 O-cm. The films crystallization shows small peak after thin film growth, however treatment process induced strong peak (222) and (441). The optimization point of treatment process can improve thin films properties that can apply thin films for low energy photodiode.

Effects of Post-Annealing on the Properties of ZnO:Ga Films with High Transparency (94%) and Low Sheet Resistance (29 Ω/square).

This study presents gallium-doped zinc oxide (ZnO:Ga, GZO) thin films. GZO thin films with both high transparency and low sheet resistance were prepared by RF sputtering and then post-annealed under nitrogen and hydrogen forming gas. With post-annealing at 450 °C, the proposed films with a film thickness of 100 nm showed high transparency (94%), while the sheet resistance of the films was reduced to 29 Ω/square, which was comparable with the performances of commercial indium tin oxide (ITO) samples. Post-annealing under nitrogen and hydrogen forming gas enhanced the films' conductivity while altering the thin-film composition and crystallinity. Nitrogen gas played a role in improving the crystallinity while maintaining the oxygen vacancy of the proposed films, whereas hydrogen did not dope into the thin film, thus maintaining its transparency. Furthermore, hydrogen lowered the resistance of GZO thin films during the annealing process. Then, the detailed mechanisms were discussed. Hydrogen post-annealing helped in the removal of oxygen, therefore increasing the Ga3+ content, which provided extra electrons to lower the resistivity of the films. After the preferable nitrogen/hydrogen forming gas treatment, our proposed films maintained high transparency and low sheet resistance, thus being highly useful for further opto-electronic applications.

A selective NH3 gas sensor based on (Ag2O)1-x(SnO2)x nanocomposites thin films at various operating temperatures

تم استخدام تقنية ترسيب الليزر النبضي (PLD) للتحضير الأغشية الرقيقة (Ag2O)1-x(SnO2)x النانوية المركبة بنسب مختلفة من x=(0, 0.2,0.4) من النسب الوزنية المرسبة على قواعد زجاجية. تم تلدين الأفلام بعد ذلك في الهواء لمدة ساعتين عند 300 درجة مئوية. تم تأكيد تشكيل المركب (Ag2O)1-x(SnO2)x من خلال تحقيق حيود الأشعة السينية(XRD). وفقًا للفحص المجهري الإلكتروني الماسح (FESEM) ، كانت جزيئات (Ag2O)1-x(SnO2)x التي تم إنشاؤها كروية الشكل. تم أستخدم تحليل مطياف تشتت الاشعة السينية (EDX) لتأكيد العناصر الموجودة في الأفلام المركبة.اظهر تحليل القوة الذرية المجهري (AFM) أن الأفلام الناتجة لها حجم حبيبي بين 37.68 -49.57 نانومتر وخشونة متوسط الجذر التربيعي (RMS ) من 4.92 إلى 8.22 نانومتر. تحتوي الأفلام المحضرة على فجوة طاقة مباشرة بين 2.06 و 3.36 الكترون فولت ، وفقاً لبيانات لبيانات المطياف المرئي للأشعة فوق البنفسجية (UV-Vis) . تم اختبار الأفلام لاستشعار NH3 تحت درجات حرارة تشغيل مختلفة. الاختلافات الملحوظة في مقاومة الغشاء الرقيق لاستجابة استشعار الغاز تدل على الموصلية من النوع n او النوع p عند الغازالمختزل ، تزداد مقاومة أفلام (Ag2O)1-x(SnO2)x عندما تكون x=0, 0.2wt ، مما يشير إلى أن الأفلام من النوع p ، ومع ذلك ، فإن الفيلم الرقيق يعرض السلوك العكسي عندما x = 0.4wt ، مما يشير إلى أنه من النوع n بالإضافة إلى ذلك ، أظهرت جميع الأفلام التي تم إنتاجها حساسية لغاز NH3 بتركيز 95 جزء في المليون. يمتلك الغشاء الرقيق Ag2O حساسية بنسبة 50.5٪ عند درجة حرارة تشغيل 200 درجة مئوية مع أوقات استجابة واسترداد تبلغ 22.5 و 39.6 ثانية على التوالي.علاوة على ذلك أظهرت الأغشية الرقيقة المركبة حساسية أكبرمن الأغشية الرقيقة المصنوعة من أوكسيد الفضة النقي.

Independent microscale sensing of phase interface and surface temperature during droplet evaporation

Despite the important and pervasive nature of evaporative heat transfer phenomena, fundamental questions still remain about the microscopic processes that occur in and around individual droplets on a surface. In order to understand the underlying physics behind evaporative heat transfer, it is critical to have information at the individual droplet level regarding the surface temperature distribution with time as well as the location and speed of the moving multiphase contact line (MCL). In this work, a multifunctional microscale device comprised of a resistance heater, an array of spatially distributed thin-film resistance temperature detectors, and a phase interface sensing capacitance micro-sensor array has been utilized to measure the local heat transfer characteristics and MCL behavior simultaneously for the evaporation of individual sessile water droplets on a horizontal heated surface. The resistance- and capacitance-based operating principles of the micro-device means that it is capable of detecting temperature changes and tracking MCL at the microscale in real time even for applications with limited or no visibility such as within thermal management hardware or processing equipment. Importantly, having knowledge of the MCL’s location and speed with microscale precision allows for its influence on surface temperature and heat transfer to be directly studied rather than inferred. Results show that the MCL passage precedes the change in local surface temperature and the duration of the time difference between these events depends on the MCL’s speed. In addition, the passage of the MCL accounts for more than 70% of the overall temperature change during the evaporation process.

Microstructure, creep properties, and electrical resistivity of magnetron sputtering deposited SAC305 thin films

This paper investigates the surface morphology, mechanical properties, and electrical resistivity of 96.5Sn–3.0Ag–0.5Cu (SAC305) thin films deposited on Si and SiO2 substrates through RF magnetron sputtering. Various deposition parameters were tested using both DC and RF power sources at different pressures and powers to produce robust continuous films. The most optimal surface morphology, with an average grain size of ∼1 μm and a thickness of ∼2.2 μm, was accomplished at a pressure of 2.4 mTorr and 200 W power. After polishing, a uniform thickness of 1800 nm with a mean roughness (Ra) of 14.9 nm was obtained. The samples contained polycrystalline β-Sn grains at (200) diffraction planes with a preferred orientation 2θ of 30.70°. Although the XRD pattern did not indicate any Ag peaks, weak peaks of Ag3Sn were observed at 2θ of 37.60° and 39.59°, corresponding to diffraction planes (020) and (211), respectively. The electrical resistivity of the SAC305 thin film deposited on the SiO2 substrate and of the bulk SAC305 samples were measured as 19.6 and 13.7 μΩ cm, respectively. It was noted that changes in hold time at peak loads or the rate of loading in the creep experiments did not significantly influence the creep properties of the SAC305 bulk or thin film material.

High-temperature oxidation resistance of CrAlN thin films prepared by DC reactive magnetron sputtering

CrAlN thin films were prepared by using the reactive DC unbalanced magnetron sputtering method from the single alloy target on a silicon substrate. The effect of annealing temperature in the air which ranges from 500℃ to 900℃ for 1 h on phase structure, film composition, surface morphology, microstructure, and hardness was investigated by XRD, EDS, FE-SEM, and Nanoindentation techniques, respectively. The high-temperature (up to 900℃) oxidation resistance of the thin film was also evaluated. The result shows that solid solutions of (Cr,Al)N with (111), (200), and (220) planes for the as-deposited film and no oxide phase were found after annealing with different temperatures. The O content slightly increases with an increase in the annealing temperature with various Cr, Al, and N contents found by the EDS. From the FE-SEM result, as increased annealing temperature, the evolution of cross-sectional morphology from dense to compact columnar structure was exhibited but the oxides layer was not detected. These results concluded that the as-deposited thin film showed good oxidation resistance when annealed in air at an elevated temperature reaching 900℃. Moreover, the film’s hardness decreased from 61.19 GPa to 50.11 GPa with increasing the annealing temperature observed by the Nanoindentation technique.

Effects of HfO2 addition on the plasma resistance of Y2O3 thin films deposited by e-beam PVD

Ceramic Y2O3 thin films are often used to coat the inner walls of etching equipment during semiconductor manufacturing to protect them from bombardment by high-energy plasma ions, which can degrade the equipment and cause semiconductor contamination. In this study, the effects of HfO2 addition to the Y2O3 thin film on the plasma resistance were investigated. Thin films were fabricated using electron beam-physical vapor deposition. The addition of HfO2 maintained the cubic Y2O3 crystalline structure while substantially improving the etch resistance during fluorine-based plasma etching. X-ray photoelectron spectroscopy analysis of the etched surface showed that HfO2 addition resulted in a lower F/(O + F) ratio, thus promoting the formation of more Y–O bonds that are more resistant to physical sputtering. Additionally, the analysis indicated that Hf4+ was more likely to be removed from the etched surface than Hfx+ (x < 4). This novel strategy is expected to aid in the development of improved plasma-resistant ceramic materials.

Improved Ballistic Impact Resistance of Nanofibrillar Cellulose Films with Discontinuous Fibrous Bouligand Architecture.

Natural protective materials offer unparalleled solutions for impact-resistant material designs that are simultaneously lightweight, strong, and tough. Particularly, the Bouligand structure found in the dactyl club of mantis shrimp and the staggered structure in nacre achieve excellent mechanical strength, toughness, and impact resistance. Previous studies have shown that hybrid designs by combining different bioinspired microstructures can lead to enhanced mechanical strength and energy dissipation. Nevertheless, it remains unknown whether combining Bouligand and staggered structures in nanofibrillar cellulose (NFC) films, forming a discontinuous fibrous Bouligand (DFB) architecture, can achieve enhanced impact resistance against projectile penetration. Additionally, the failure mechanisms under such dynamic loading conditions have been minimally understood. In our study, we systematically investigate the dynamic failure mechanisms and quantify the impact resistance of NFC thin films with DFB architecture by leveraging previously developed coarse-grained models and ballistic impact molecular dynamics simulations. We find that when nanofibrils achieve a critical length and form DFB architecture, the impact resistance of NFC films outperforms the counterpart films with continuous fibrils by comparing their specific ballistic limit velocities and penetration energies. We also find that the underlying mechanisms contributing to this improvement include enhanced fibril sliding, intralayer and interlayer crack bridging, and crack twisting in the thickness direction enabled by the DFB architecture. Our results show that by combining Bouligand and staggered structures in NFC films, their potential for protective applications can be further improved. Our findings can provide practical guidelines for the design of protective films made of nanofibrils.

Tailoring flake size and chemistry to improve impact resistance of graphene oxide thin films

Multilayered graphene oxide (MLGO) possesses high elastic modulus and strength, as well as enhanced resistance to inter-layer sliding from functional groups. This makes it a promising candidate for impact-resistant thin films and nanocomposites. However, the effects functionalization and flake size on the physics of MLGO failure under high-strain rate impact remains to be fully understood. While laser induced projectile impact tests (LIPIT) have enabled microballistic characterization of MLGO, the dynamics of interlayer sliding processes cannot be accurately studied in physical experiments due to resolution challenges of existing techniques. Here we utilize systematically coarse-grained molecular dynamics to simulate MLGO under high-rate microballistic impact, explicitly accounting for functional group distributions while approaching micron-size specimen dimensions. In doing so, we evaluate the effects of oxidation level on the thin films’ ability to dissipate ballistic energy. We additionally explore effects of varying flake size on these systems, improving on studies that only consider infinite flake dimensions. The primary failure mechanism of these thin films (consisting of relatively small flakes) is found to be sliding of the GO flakes as no bonds were broken. We discover that elevated levels of oxidation increase the amount of energy required to penetrate the film, as do larger GO flake sizes as they increase energy dissipation via friction between sliding flakes. These findings illustrate the potential for MLGO films to be tailored for maximum ballistic energy dissipation, providing a starting point to design impact-resistant GO materials for diverse applications.