Low friction CrN/TiN multilayer coatings prepared by a hybrid high power impulse magnetron sputtering/DC magnetron sputtering deposition technique

High power impulse magnetron sputtering (HIPIMS) has gained increasing scientific and industrial attention as it allows high plasma densities without the drawback of droplet formation. Recently, we showed that by a combination of HIPIMS with dc magnetron sputtering the properties of the coatings are comparable to those prepared solely with HIPIMS, but with the advantage of increased deposition rate.Here, we show that for CrN_HIPIMS/TiN_DCMS multilayered coatings the friction coefficient µ decreases from 0.7 to 0.35 (with an almost constant hardness H around 25 GPa, and modulus of indentation around 375 GPa) when decreasing the bilayer period λ from 7.8 to 6.4 nm, while keeping the CrN_HIPIMS layer thickness constant at 3.2 nm. A further reduction of the friction coefficient at room temperature dry-sliding testing to ∼ 0.25 or 0.05 is obtained when an additional HIPIMS cathode equipped with a Cr or Ti target material, respectively, is added to the process. Contact angle measurements of distilled water drops on as deposited film surfaces were carried out to investigate their wettability. The measurements show, that with increasing contact angle from 70° to 90°, for the individual coatings prepared, also their friction coefficient increases from ∼ 0.05 to ∼ 0.8. The depositions of all coatings were achieved with two- and threefold substrate rotation, which meet the industrial requirements of uniform deposition on complex shaped specimens.     

Antibacterial property of CuCrO2 thin films prepared by RF magnetron sputtering deposition

The present study investigates the antibacterial properties of CuCrO₂ thin film surfaces against Escherichia coli (E. coli) bacteria. Single-phase delafossite type copper-chromium oxide (CuCrO₂) thin films were prepared on glass substrate by radio-frequency (RF) magnetron sputtering, followed by two-step post-deposition annealing at 400 °C with 5% forming gas and at 600 °C in a nitrogen atmosphere. The structure of the CuCrO₂ thin films was confirmed by X-ray diffraction. The transmittance properties were measured by a UV–Vis spectrometer. The ISO 22196 method was utilized to evaluate the colony forming unit (CFU) of E. coli on the CuCrO₂ surface after several hours. The experimental results find the CuCrO₂ surface to exhibit superior antibacterial performance and an optical transparency of >70% in the visible region with a thickness of 100 nm. A novel transparent antibacterial coating has been demonstrated in the present study.     

The influence of oxygen pressure on the growth of CuO nanostructures prepared by RF reactive magnetron sputtering

Copper oxide films were prepared by RF reactive magnetron sputtering at different percentages of oxygen pressure in a Ar:O₂ reactive gas mixture at room temperature. The structural and optical properties of CuO films were investigated by a field emission scanning electron microscope, Raman spectroscopy, X-ray diffraction and UV–Visible spectrophotometer. The structure of the deposited film changed from a mixture of Cu₂O + CuO phases to a pure CuO phase with an increase in oxygen percentage. In addition the crystallite size increased from 12 to 24 nm as the oxygen pressure percentage increased. The optical transmittance significantly increased with the increase of the oxygen pressure percentage and the optical band gap of the film increased from 1.33 to 1.41 eV. The film prepared with 30 and 40 % oxygen pressure showed (002) crystallographic orientation. The I–V characteristic of p-CuO/n-Si heterojunction diode was also found to be dependent on the oxygen pressure percentage.     

The influence of YSZ interlayer on microstructures and dielectric properties of BST thin films prepared by RF magnetron sputtering

(Ba_{1 − x} Sr _x )TiO₃ (BST) thin films were deposited on Pt/Ti/SiO₂/Si and YSZ/Pt/Ti/SiO₂/Si substrates by radio frequency (RF) magnetron sputtering. The influence of YSZ interlayer on microstructures and dielectric properties of BST thin films were investigated by X-ray diffraction, atomic force microscopy, scanning electron microscopy and dielectric frequency spectra. It was found that the preferred orientation of BST thin films could be tailored by insertion of YSZ interlayer and adjusting the thickness of YSZ interlayer. The BST thin films deposited on YSZ interlayer exhibited a more compact and uniform grain structure than that deposited directly on Pt electrode. Dielectric measurement revealed that the BST thin films deposited on 10 nm YSZ interlayer have the largest dielectric constant and a low dielectric loss tangent. The enhanced dielectric behavior is mainly attributed to the YSZ interlayer which serves as an excellent seeding layer to enhance the crystallization of subsequent BST films layer, and a smaller thermal stress field built up at the interface between YSZ interlayer and BST film layer.     

The high power impulse magnetron sputtering discharge as an ionized physical vapor deposition tool

Various magnetron sputtering tools have been developed that provide a high degree of ionization of the sputtered vapor referred to as ionized physical vapor deposition (IPVD). The ions can be controlled with respect to energy and direction as they arrive to the growth surface which allows for increased control of film properties during growth. Here, the design parameters for IPVD systems are briefly reviewed. The first sputter based IPVD systems utilized a secondary plasma source between the target and the substrate in order to generate a highly ionized sputtered vapor. High power impulse magnetron sputtering (HiPIMS) is a recent sputtering technique that utilizes IPVD where a high density plasma is created by applying high power pulses at low frequency and low duty cycle to a magnetron sputtering device. A summary of the key experimental findings for the HiPIMS discharge is given. Measurements of the temporal and spatial behavior of the plasma parameters indicate electron density peak, that expands from the target with a fixed velocity. The discharge develops from an inert sputtering gas dominated to a sputtered vapor dominated during the pulse. The high electron density results in a high degree of ionization of the deposition material.     

Effects of heat treatment on properties of ITO films prepared by rf magnetron sputtering

Indium tin oxide (ITO) films were deposited on glass substrates by rf magnetron sputtering using a ceramic target (In₂O₃-SnO₂, 90-10 wt%) without extra heating. The post annealing was done in air and in vacuum, respectively. The effects of annealing on the structure, surface morphology, optical and electrical properties of the ITO films were studied. The results show that the increase of the annealing temperature improves the crystallinity of the films, increases the surface roughness, and improves the optical and electrical properties. The transmittance of the films in visible region is increased over 90% after the annealing process in air or in vacuum. The resistivity of the films deposited is about 8.125×10⁻⁴ Ω cm and falls down to 2.34×10⁻⁴ Ω cm as the annealing temperature is increased to 500°C in vacuum. Compared with the results of the ITO films annealed in air, the properties of the films annealed in vacuum is better.     

The high power impulse magnetron sputtering discharge as an ionized physical vapor deposition tool

Various magnetron sputtering tools have been developed that provide a high degree of ionization of the sputtered vapor referred to as ionized physical vapor deposition (IPVD). The ions can be controlled with respect to energy and direction as they arrive to the growth surface which allows for increased control of film properties during growth. Here, the design parameters for IPVD systems are briefly reviewed. The first sputter based IPVD systems utilized a secondary plasma source between the target and the substrate in order to generate a highly ionized sputtered vapor. High power impulse magnetron sputtering (HiPIMS) is a recent sputtering technique that utilizes IPVD where a high density plasma is created by applying high power pulses at low frequency and low duty cycle to a magnetron sputtering device. A summary of the key experimental findings for the HiPIMS discharge is given. Measurements of the temporal and spatial behavior of the plasma parameters indicate electron density peak, that expands from the target with a fixed velocity. The discharge develops from an inert sputtering gas dominated to a sputtered vapor dominated during the pulse. The high electron density results in a high degree of ionization of the deposition material.     

Structural properties of Eu-doped GaN films prepared by RF magnetron sputtering

Films of Eu-doped GaN (GaN:Eu) were grown on c-plane of sapphire (c-Al₂O₃), GaAs(1 0 0), Si(1 0 0) and glass substrates by RF magnetron sputtering method. The X-ray diffraction (XRD) measurement of the sputtered film was carried out. For GaN:Eu and undoped GaN, the lattice constants c and a of as-grown films were larger than those of the bulk GaN. After annealing, the lattice constants c and a of the films decreased.     

射频磁控溅射硅薄膜的制备与结构研究

采用拉曼光谱、光学显微镜、透射电镜研究了不同衬底温度、腔体气压对射频磁控溅射法制备的不含氢硅薄膜相结构和形貌的影响.结果表明430℃时薄膜中出现微晶相,平均晶粒尺寸2.8nm.腔体内杂质及衬底表面的显微缺陷会诱发薄膜针孔、凹坑等缺陷的产生.低温、高压会导致薄膜中空洞缺陷的密集.     

Comparison of chromium nitride coatings deposited by DC and RF magnetron sputtering

Chromium nitride coatings were deposited by DC and RF reactive magnetron sputtering on AISI 304 stainless steels without substrate heating. A Cr₂N phase was formed in the RF sputtered coatings with a low N₂ flow content ranging within 30-50%. A NaCl type CrN_x phase was obtained by DC magnetron sputtering with different N₂ flow contents. The coating hardness increased with the increase of the N₂ flow content. When the coatings deposited with the same N₂ flow content were compared, the hardness of the RF sputtered CrN_x was higher than that of the DC sputtered CrN_x, which was mainly due to the distinct difference between the dense structure (RF process) and the porous structure (DC process). The RF sputtered CrN_x coatings showed an excellent adhesion strength as compared to the DC sputtered coatings. By selecting the deposition method and optimizing the N₂ flow content, CrN_x coatings with a preferred microstructure could be obtained, which would be a candidate material for research and applications in nano-science.     

Comparison between the effects of CdCl2 heat treatment on CdTe films prepared by RF magnetron sputtering and close spaced sublimation methods

CdTe films were prepared on Fluorine-doped tin oxide substrate by RF magnetron sputtering and close spaced sublimation (CSS) methods, respectively. These CdTe films were then treated with a wet CdCl₂ heat process at different temperatures. The structural and optical properties of CdTe films were investigated by X-ray diffraction, scanning electron microscope and UV–Visible spectrophotometer. The results reveal that both types of CdTe films have a better crystalline and larger grain size after CdCl₂ heat treatment. However, the (422) peak has a more preferential orientation than (511) peak after CdCl₂ activation for CdTe films prepared by sputtering method, while these two peaks almost have the same intensity for CSS-prepared CdTe films. The transmittance of CdTe films prepared by CSS is apparently lower than sputtered CdTe films. Correspondingly, the efficiency of solar cells with CSS-prepared CdTe is 7.3, 2.6 % of sputtered CdTe films.     

溅射功率对磁控溅射ZnO∶Al(ZAO)薄膜性能的影响

采用射频磁控溅射工艺,以高密度氧化锌铝陶瓷靶为靶材,衬底温度控制在室温,在玻璃基底上制备了透明导电Zn O∶Al(ZAO)薄膜。利用X射线衍射仪(XRD)、原子力显微镜(AFM)、紫外-可见光谱仪和范德堡法,系统研究了不同溅射功率对薄膜的结构、形貌及光电特性的影响。结果表明,不同溅射功率对薄膜的光透射率影响不大,而对薄膜结晶和电学性能影响较大。XRD表明薄膜为良好的c轴择优取向;可见光区(400~600 nm)平均透过率达到85%以上;在120W下沉积的薄膜电学性能达到了最佳。     

TiNx coatings prepared by d.c. reactive magnetron sputtering

In this paper we describe an investigation of the correlation between the microstructure, morphology and microhardness of non-stoichiometric TiN_x films prepared by reactive d.c. magnetron sputtering in a narrow interval of partial pressure p_N2 of nitrogen. It was found that TiN_x films sputtered at p_N2 < p_N2crit have a quasi-amorphous microstructure and are extremely hard. The results of a detailed experimental study of the films' microstructure, morphology, microhardness and deposition rate are given. It is shown that reactive d.c. magnetron sputtering makes possible the production of TiN_x films with the high deposition rate of 0.5microm min⁻¹.     

射频磁控溅射纳米SiC薄膜及其拉曼和红外分析

用射频磁控溅射法在玻璃衬底上制备出一系列衬底温度不同的纳米碳化硅薄膜,衬底温度分别为室温,200、400、600、700℃,并对样品进行了Raman和傅立叶红外测试分析.结果表明,随衬底温度的升高,薄膜结晶度提高,其晶粒尺寸为纳米数量级.通过FTIR不仅观察到SiC的TO声子在红外被激活,而且LO声子在粒径很小或薄膜很薄时也能在红外被激活,体现了纳米SiC较强的红外吸收特性.     

反应RF磁控溅射法制备非晶氧化硅薄膜及其特性研究

在氧气和氩气的混合气体中,在没有额外加热的条件下用反应射（RF）溅射硅靶制备了非晶氧化硅（a-SiO2)薄膜,并测试分析了薄膜的结构和电特性与O2／Ar流量比的关系。当固定氩气流量,改变氧气流量时,薄膜沉积速率先急剧减少,再增大,然后又减少。当O2／Ar≥0．075时,得到满足化学配比的氧化硅薄膜。并且,随着O2／Ar流量比的增大,薄膜的电阻,电场击穿强度都有所增大,而在HF缓冲溶液（BHF）中的腐蚀速率下降,所有的样品中无明显的H－OH水分子的红外吸收峰。比较发现反应射频（RF）磁控溅射法制备的a-SiO2薄膜具有良好的致密性和绝缘性。     

Heating of polymer substrate by discharge plasma in radiofrequency magnetron sputtering deposition

The substrate used for the thin film deposition in a radiofrequency magnetron sputtering deposition system is heated by the deposition plasma. This may change drastically the surface properties of the polymer substrates. Deposition of titanium dioxide thin films on polymethyl methacrylate and polycarbonate substrates resulted in buckling of the substrate surfaces. This effect was evaluated by analysis of atomic force microscopy topography images of the deposited films. The amount of energy received by the substrate surface during the film deposition was determined by a thermal probe. Then, the results of the thermal probe measurements were used to compute the surface temperature of the polymer substrate. The computation revealed that the substrate surface temperature depends on the substrate thickness, discharge power and substrate holder temperature. For the case of the TiO₂ film depositions in the radiofrequency magnetron plasma, the computation indicated substrate surface temperature values under the polymer melting temperature. Therefore, the buckling of polymer substrate surface in the deposition plasma may not be regarded as a temperature driven surface instability, but more as an effect of argon ion bombardment.     

Structural and optical properties of yttrium trioxide thin films prepared by RF magnetron sputtering

Yttrium trioxide (Y₂O₃) thin films have been deposited on silicon (111) at different RF powers and the sputtering pressures by RF magnetron sputtering. The influences of the RF power and the sputtering pressures on the structural and optical properties of Y₂O₃ thin films were investigated by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), atomic force microscope (AFM) and spectroscopic ellipsometer (SE). The results show that chemical composition of as-deposited Y₂O₃ film is apparently close to the stoichiometric ratio and it is crystallized but crystallinity is poor. The monoclinic and cubic fluorite-like structure can coexist in as-deposited Y₂O₃ film. A four-layer-structured optical model consisting of silicon substrate, silicon dioxide (SiO₂) interlayer, Y₂O₃ layer and a surface roughness (SR) layer is built for interpreting preferably the results measured by spectroscopic ellipsometry. With the increase of RF power or decrease of sputtering pressure, the refractive index and optical bandgap of sputtered Y₂O₃ film is increased and the extinction coefficients is decreased.     

Structural and optical properties of yttrium trioxide thin films prepared by RF magnetron sputtering

Yttrium trioxide (Y₂O₃) thin films have been deposited on silicon (111) at different RF powers and the sputtering pressures by RF magnetron sputtering. The influences of the RF power and the sputtering pressures on the structural and optical properties of Y₂O₃ thin films were investigated by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), atomic force microscope (AFM) and spectroscopic ellipsometer (SE). The results show that chemical composition of as-deposited Y₂O₃ film is apparently close to the stoichiometric ratio and it is crystallized but crystallinity is poor. The monoclinic and cubic fluorite-like structure can coexist in as-deposited Y₂O₃ film. A four-layer-structured optical model consisting of silicon substrate, silicon dioxide (SiO₂) interlayer, Y₂O₃ layer and a surface roughness (SR) layer is built for interpreting preferably the results measured by spectroscopic ellipsometry. With the increase of RF power or decrease of sputtering pressure, the refractive index and optical bandgap of sputtered Y₂O₃ film is increased and the extinction coefficients is decreased.