Deposition and Adhesion Characterization of Ti(BN:MoS2) Based Composite Thin Films Prepared by Closed-Field Unbalanced Magnetron Sputtering

Composite structured solid thin films were deposited on 52100 tool steel by co-sputtering from BN, TiB₂, MoS₂ and Ti targets using a closed-field unbalanced magnetron sputtering process (CFUBMS). The structural and mechanical properties of the composite structured coatings were investigated. The composition and morphology of the films were investigated using X-ray diffraction and scanning electron microscopy (SEM). The adhesion properties of the films were characterized by the use of a Revetest-scratch tester. The adhesion test results indicated that bias voltage was the most effective coating parameter related to the critical load.     

Different nanostructures identified in boron nitride thin films grown on Si (100) by rf magnetron sputtering

Boron nitride (BN) thin films grown on Si (100) substrates by radio frequency magnetron sputtering, with varying growth parameters, are studied by high-resolution transmission electron microscopy (HRTEM). The HRTEM study reveals the presence of several interesting nanostructures in the BN films. Nanotube-like configurations, nanoarches and nanohorns are observed, as well as well-orientated cubic BN nanocrystals. It is found that several configurations of the turbostratic BN planes (properly orientated or curved) can act, in the same film, as nucleation sites for the growth of the cubic phase.     

Physical properties of Al-doped ZnO films deposited on nonwoven substrates by radio frequence magnetron sputtering

In this study, the polyethylene terephthalate (PET) spunbonded nonwoven materials were used as substrates for creating electro-optical functional nanostructures on the fiber surfaces. A magnetron sputter coating was used to deposit Al-doped ZnO (AZO) films onto the nonwovens. The influences of the deposition time on the structural, optical, and electrical properties of AZO films were investigated. Atomic force microscopy (AFM) was employed to examine the topography of the fibers. The AFM observation revealed a significant difference in the morphology of the fibers before and after the AZO sputter coating. The examination by UV–visible spectrophotometer analysis showed that the nonwovens deposited with transparent nanostructure AZO films had better UV absorption, and an average transmittance was approximately 50% in the visible light wavelength region. The surface conductivity of the materials was analyzed using a four-probe meter, and it was found that electrical resistance was significantly decreased as the sputtering time increased.     

Room temperature sputtering deposition of high-haze Ga-doped ZnO transparent conductive thin films on self-textured bio-based poly(ethylene 2, 5-furandicarboxylate) substrates

In this work, bio-based poly(ethylene 2,5-furandicarboxylate) (PEF) films were prepared by drop-casting method and used as substrates for depositing Ga-doped ZnO (GZO) transparent conductive thin films. Results showed that the 300-nm GZO thin films deposited on PEF substrates exhibited haze values above 65% at 550 nm without post-treatment. The high haze value was because of the large surface roughness of PEF films. The total optical transmittance and electrical properties of GZO thin films on PEF were comparable to those of GZO thin films on PET. The present study provides a simple way for the sputtering deposition of high-haze transparent conductive thin films on flexible substrates.     

Annealing effects on the microstructure and magnetic properties of Y3Fe5O12 films deposited on Si/SiO2 substrates by RF magnetron sputtering

Crack-free Yttrium iron garnet (Y₃Fe₅O₁₂, YIG) thin films were successfully deposited on Si/SiO₂ substrates by RF magnetron sputtering, through controlling the annealing temperature and cooling rate during post-annealing process. The annealing condition dependences of crystallinity, microstructures and magnetic properties of YIG films were investigated. With the increase of the annealing temperature, the saturation magnetization of YIG films increases and the coercive field decreases, while the ferromagnetic resonance (FMR) linewidth becomes wider. The films annealed at 750 °C with cooling rate of 1 °C/min are crack-free and present excellent comprehensive performances, the corresponding coercive field is 32 Oe and the FMR linewidth is 57 Oe at 9.4 GHz. These results indicate that high-quality crack-free YIG films with excellent magnetic properties can be achieved on Si/SiO₂ substrates by controlling the annealing process, which makes it more convenient to fabricate low-loss microwave integrated devices.     

Thermochromic properties of ZnO/VO2/ZnO films on soda lime silicate glass deposited by RF magnetron sputtering

A smart window based on VO₂ is a promising thermochromic (TC) glass that can regulate heat flow through windows by solar modulation near room temperature. TC glasses with high visible-light transmittance and large difference in infrared transmittance between high- and low-temperature VO₂ phases are required to save large amounts of energy in buildings. VO₂-based multilayer films with a buffer layer and/or an anti-reflective (AR) layer are used when the films are deposited by sputtering. In this study, VO₂-based multilayer films were prepared on soda lime glass using ZnO as both the buffer and the AR layers. The structure of the multilayer film was simulated using the optical constants measured from the deposited films. The effect of buffer and AR layers on the TC properties of VO₂-based multilayer films prepared by sputtering was investigated by simulation of the multilayer structure and deposition of the films with the simulated structure. The TC properties were measured and compared with the calculated properties. Improved TC properties (luminous transmittance (T_lum) of ～50%/46% (30 °C/80 °C) and solar modulation ability (ΔT_sol) of ～14%), compared to those without the buffer and AR layer, were obtained from the ZnO/VO₂/ZnO film deposited on glass. The calculated transmittances agree better with the measured ones when the optical constants measured directly from the deposited films are used and the roughnesses of the surface/interface of the multilayer films are considered in the calculation of the optical constants.     

Effect of substrate temperature on the structural,electrical, and optical properties of GZO/ZnO films deposited by radio frequency magnetron sputtering

Ga-doped ZnO (GZO)/ZnO bi-layered films were deposited on glass substrates by radio frequency magnetron sputtering at different substrate temperatures of 100, 200 and 300 °C to investigate the effects of substrate temperature on the structural, electrical, and optical properties of the films. Thicknesses of the GZO and ZnO buffer layer were kept constant at 85 and 15 nm by controlling the deposition times.     

Effect of deposition temperature and quality of free-standing diamond substrates on the properties of RF sputtering ZnO films

Highly c-axis oriented ZnO film is often deposited on diamond substrates by RF magnetron sputtering and widely used for high frequency surface acoustic wave (SAW) devices. Deposition temperature is a key factor affecting the quality of the ZnO film. Different quality polished free-standing diamond films prepared by DC Arc Plasma Jet were used as the substrates to deposit ZnO films at different temperatures. Effect of the deposition temperature and the quality of the diamond films on the properties of the ZnO films were investigated by means of scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results show that highly c-axis oriented ZnO films can be much easier deposited on the optical-grade diamond films with < 111> preferred orientation than the tool-grade diamond films with < 220> preferred orientation. The optimal deposition temperature is 200 °C for highly c-axis oriented and lower roughness ZnO films. Acoustic phase velocity of more than 10,000 m/s for the SAW devices based on the ZnO/optical-grade free-standing diamond films was obtained.     

Effect of Fe-doping on the structural,optical and magnetic properties of ZnO thin films prepared by RF magnetron sputtering

In this paper, we report the fabrication and systematic characterization of Fe Doped ZnO thin Films. Fe_xZn_1−x O (x=0<0.05) films were prepared by RF magnetron sputtering on Si (400) substrate. Influence of Fe doping on structural, optical and magnetic properties has been studied. The X-ray diffraction (XRD) analysis shows that Fe doping has affected the crystalline structure, grain size and strain in the thin films. The best crystalline structure is obtained for 3% Fe Doping as observed from Atomic Force Microscopy (AFM) and X-ray diffraction (XRD). The magnetic properties studied using Vibrating Sample Magnetometer reveals the room temperature ferromagnetic nature of the thin films. However, changing the Fe concentration degrades the magnetic property in turn. The mechanism behind the above results has been discussed minutely in this paper.     

Effect of the substrate temperature on the physical characteristics of amorphous carbon films deposited by d.c. magnetron sputtering

The growth rate, composition, electrical resistivity, mass density, refractive index and microstructure of amorphous carbon (a-C) films prepared by direct current (d.c.) magnetron sputtering were investigated as functions of the substrate temperature (50–350°C). The hydrogen content determined by elastic recoil detection analysis (ERDA) and the electrical resistivity of films were found to be dependent on both the base pressure in the deposition chamber and substrate temperature. For films deposited below 200°C, the hydrogen content was less than 2 at.% and the substrate temperature was the only parameter which affected their electrical resistivity. The electrical resistivity decreased from 0.2 to 0.03 Ωcm as the substrate temperature increased from 50 to 200°C. The mass density of films evaluated from Rutherford backscattering (RBS) data and film thickness decreased from 2.2 to 1.4 g cm⁻³ with increasing substrate temperature. A linear relationship between the refractive index and the mass density of a-C films was clearly established. From the optical measurements, the decrease in mass density was correlated to an increase in porosity of films with increasing substrate temperature. The decrease in electrical resistivity with increasing substrate temperature was attributed to a graphitization of a-C films. This modification of the microstructure of a-C films as the deposition temperature was varied from 50 to 350°C was observed by examination of the cross-section of samples by transmission electron microscopy and Raman spectroscopic analyses of a-C films.     

Structural and mechanical investigations of magnetron sputtering TiO<Subscript>2</Subscript>/Ti/TiN multilayer films on Si(100) substrate

TiO₂/Ti/TiN multicompositional coating was prepared by DC reactive magnetron sputtering (MS) at a temperature of 150°C using a combination of a Ti metal target and a pure Ar, an Ar–O₂ mixture, or an Ar–N₂ mixture discharge gas, onto a Silicon(100) substrate. This system represents nano-structured multilayer substrate model for biomedical application as well as substrate models to reproduce the bulk titanium surface. This substrate model (Ti/TiN/Si(100)) makes possible and easy mechanical and microscopic characterization in particular for transmission electron microscopy after biocompatible test. The model multilayer TiO₂/Ti/TiN/(100) was obtained after preparation of two intermediate samples: TiN/Si(100) and Ti/TiN/Si(100). Structural (X-ray diffraction), morphological (scanning electron and atomic force microscopy) as well as mechanical (hardness and elastic modulus) studies of the MS films were performed.     

Characteristics of highly (001) oriented (K,Na)NbO3 films grown on LaNiO3 bottom electrodes by RF magnetron sputtering

(K,Na)NbO₃ ferroelectric films were grown on LaNiO₃ coated silicon substrates by RF magnetron sputtering. The conductive LaNiO₃ films acted as seed layers and induced the highly (001) oriented perovskite (K,Na)NbO₃ films. Such films exhibit saturated hysteresis loops and have a remnant polarization (2P_r) of 23 μC/cm², and coercive field (2E_c) of 139 kV/cm. The films showed a fatigue-free behavior up to 10⁹ switching cycles. A high tunability of 65.7% (@300 kV/cm) was obtained in the films. The leakage current density of the films is about 6.0×10^?8 A/cm² at an electric field of 50 kV/cm.     

Cracking and loss of adhesion of Si3N4 and SiO2:P films deposited on Al substrates

Tensile tests in a scanning electron microscope have been performed to study the mechanical stability of different film/substrate systems consisting of films of Si₃N₄ and SiO₂ :4.5 wt% P deposited on Al substrates. Successive stages of crack development were observed: transverse through-thickness cracking of the film precedes its loss of adhesion and buckling, induced by the transverse contraction of the substrate. It was observed that the presence of a thermally grown Al₂O₃ interlayer improved the adhesion of the films by delaying the de-adhesion process. The influence of roughness on the interfacial strength was analysed from the observation of the de-adhesion of a SiO₂ :4.5 wt% P film deposited on a scratched Al substrate. The critical strain for the through-thickness cracking of each film was calculated. Then the multiple film cracking was analysed through the evolution of the crack density with the longitudinal strain. Finally, by using the point at which the film de-adhered, an interfacial fracture energy was calculated for each system.     

Characterization of single crystalline a-TiO2 films on MgAl2O4(100) substrates by MOCVD

Anatase phase TiO₂ (a-TiO₂) films have been deposited on MgAl₂O₄(100) substrates at the substrate temperatures of 500–650 °C by the metal organic chemical vapor deposition (MOCVD) method using tetrakis-dimethylamino titanium (TDMAT) as the organometallic (OM) source. The structural analyses indicated that the TiO₂ film prepared at 600 °C had the best single crystalline quality with no twins. The out-of-plane and in-plane epitaxial relationships of the film were a-TiO₂(001)||MgAl₂O₄(100) and TiO₂[100]||MgAl₂O₄[100], respectively. A uniform and compact surface with stoichiometric composition was also obtained for the 600 °C-deposited sample. The average transmittance of all the TiO₂ films in the visible range exceeded 91% and the optical band gap of the films varied from 3.31 to 3.41 eV.     

A low temperature preparation of Sr0.7Bi2 x.Ta2O9 thin films on SiO2/Si by pulsed laser deposition for application of metal-ferroelectric-insulator-semiconductor structure

Preferentially (105)-oriented Sr_0.7B1_2.8Ta₂O₉ thin films on SiO₂/n-Si(100) have been prepared by Pulsed Laser Deposition (PLD) at low temperature as low as 350°C, which is the lowest process temperature for growing Sr_xBi_yTa₂O₉(SBTO) ferroelectric thin films. Insulating properties of the SBTO film have been improved by lowering the process temperature or by increasing Sr/Bi atomic ratio from 0.7/2.8 to 0.7/2.0. After applying the low leakage SBTO films to Metal-Ferroelectric-Insulator-Semiconductor diode structures, it is finally observed that their C-V curves have counterclockwise dielectric hysteresis that indicates the films' ferroelectric hysteresis sufficiently control the Si surface potential. A low temperature process in preparing ferroelectric thin film and Sr-deficient and Bi-excess SBTO thin film by PLD method are very effective and promising for realizing an excellent MFIS FET structure.     

Effects of modulation ratio on the microstructure,mechanical and tribological properties of WB2/Cr multilayer films deposited by magnetron sputtering

WB₂/Cr multilayer films with different modulation ratios (λ = 1, 3, 5, 7, 12, and 20) were deposited by a combination of direct-current and pulse direct-current magnetron sputtering, and the number of bilayers was fixed at ten. The effect of the modulation ratio on the microstructure, mechanical and tribological properties of the multilayer films was investigated in detail. X-ray diffraction demonstrates that a preferred orientation of WB₂ (101) and Cr (110) exists, and WB₂ (101) dominates the film's growth with increasing of modulation ratio. The TEM results show that the multilayer films consist of nanograins dispersed in an amorphous matrix in WB₂ layers and polycrystalline grains in Cr layers. The hardness increases with the increasing modulation ratio, and the maximum hardness (31.1 GPa) is obtained at λ = 20. The indentation toughness presents an opposite changing trend, and the maximum indentation toughness (1.264 MPa m^1/2) is obtained in S1 at λ = 1 which conforms to the rule of mixture due to the relatively thick bilayer thickness (Λ = 160–192 nm). The wear mechanism is investigated, and the results suggest that the multilayer film with λ = 7 possesses the best wear resistance (2.06 × 10^?7 mm³/Nm), benefiting from the balance of hardness and indentation toughness.     

Effect of Ar:N2 flow rate on morphology,optical and electrical properties of CCTO thin films deposited by RF magnetron sputtering

Calcium copper titanate (CCTO) thin films were deposited on indium tin oxide (ITO) substrates using radio frequency (RF) magnetron sputtering, at selected Ar:N₂ flow rates (1:1, 1:2, 1:4, and 1:6 sccm) at ambient temperature. The effect of Ar:N₂ flow rate on the morphology, optical and electrical properties of the CCTO thin films were investigated using FESEM, XRD, AFM, Hall effect measurement, and UV–Vis spectroscopy. It was confirmed by XRD analysis that the thin films were produced is CCTO with cubic crystal structure. As the flow rate of Ar:N₂ increased up to 1:6 sccm, the thin film thickness reduced from 87 nm to 35 nm while the crystallite size of CCTO thin film decreased from 27 nm to 20 nm. Consequently, the surface roughness of thin film was halved from 8.74 nm to 4.02 nm. In addition, the CCTO thin films deposited at the highest Ar:N₂ flow rate studied, at 1:6 sccm; are having the highest sheet resistivity (13.27 Ω/sq) and the largest optical energy bandgap (3.68 eV). The results articulate that Ar:N₂ flow rate was one of the important process parameters in RF magnetron sputtering that could affect the morphology, electrical properties and optical properties of CCTO thin films.     

Influence of N2/Ar gas mixture ratio and annealing on optical properties of SiCBN thin films prepared by rf sputtering

Optical properties of amorphous thin films of silicon carbon boron nitride (Si–C–B–N) obtained by reactive sputtering has been studied. Compositional variations were obtained by changing the nitrogen and argon gas mixture ratio in the sputtering ambient. The effect of gas ratios and annealing on the optical properties was investigated. It was found that the transmittance of the films increases with nitrogen incorporation. Annealing at higher temperatures leads to considerable increase in transmittance. Optical energy gap (Tauc gap) calculated from absorption data is influenced by annealing temperatures and reactive process gas mixture. Changes in optical properties were correlated to the chemical modifications in the films due to annealing, through X-ray photoelectron spectroscopy. Studies reveal that the carbon and nitrogen concentrations in the films are highly sensitive to temperature. Annealing at higher temperatures leads to broken C–N bonds which results in the loss of C and N in the films. This is believed to be the primary cause for variations in optical properties of the films.     

Preparation of ZrO2 on flat,conducting SiO2/Si(100) model supports by wet chemical techniques; X-ray photoelectron spectroscopy and Auger depth profiling

Model supports consisting of a thin layer of SiO₂ on a silicon single crystal have been used to study ZrO₂/SiO₂/Si model catalysts made by wet chemical preparation methods. Auger depth profiling and angle-dependent X-ray photoelectron spectroscopy show that catalysts prepared by a surface reaction between zirconium ethoxide and hydroxyl groups on the SiO₂ contain a highly dispersed zirconium phase that is converted to ZrO₂ upon calcination.