Structural and mechanical properties of Al–C–N films deposited at room temperature by plasma focus device

The Al–C–N films are deposited on Si substrates by using a dense plasma focus(DPF) device with aluminum fitted central electrode(anode) and by operating the device with CH_4/N_2 gas admixture ratio of 1:1. XRD results verify the crystalline Al N(111) and Al_3CON(110) phase formation of the films deposited using multiple shots. The elemental compositions as well as chemical states of the deposited Al–C–N films are studied using XPS analysis, which affirm Al–N, C–C, and C–N bonding. The FESEM analysis reveals that the deposited films are composed of nanoparticles and nanoparticle agglomerates. The size of the agglomerates increases at a higher number of focus deposition shots for multiple shot depositions. Nanoindentation results reveal the variation in mechanical properties(nanohardness and elastic modulus)of Al–C–N films deposited with multiple shots. The highest values of nanohardness and elastic modulus are found to be about 11 and 185 GPa, respectively, for the film deposited with 30 focus deposition shots. The mechanical properties of the films deposited using multiple shots are related to the Al content and C–N bonding.     

Annealing effect on microstructure and mechanical properties of amorphous Al-C-N films

Al-C-N thin films with different Al contents were deposited on Si (1 0 0) substrates by closed-field unbalanced reactive magnetron sputtering in the mixture of argon and nitrogen gases. These films were subsequently vacuum-annealed at 700 °C and 1000 °C, respectively. The microstructures of as-deposited and annealed films were characterized by X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM); while the hardness and elastic modulus values were measured by nano-indention method. The results indicated that the microstructure of both as-deposited and annealed Al-C-N films strongly depended on Al content. For thin films at low Al content, film delamination rather than crystallization occurred after the sample was annealed at 1000 °C. For thin films at high Al content, annealing led to the formation of AlN nanocrystallites, which produced nanocomposites of AlN embedded into amorphous matrices. Both the density and size of AlN nanocrystallites were found to decrease with increasing depth from the film surface. With increasing of annealing temperature, both hardness and elastic modulus values were decreased; this trend was decreased at high Al content. Annealing did not change elastic recovery property of Al-C-N thin films.     

Superhard nanocomposite nc-TiC/a-C:H film fabricated by filtered cathodic vacuum arc technique

Superhard nanocomposite nc-TiC/a-C:H films, with an excellent combination of high elastic recovery, low friction coefficient and good H/E ratio, were prepared by filtered cathodic vacuum arc technique using the C₂H₂ gas as the precursor. The effect of C₂H₂ flow rate on the microstructure, phase composition, mechanical and tribological properties of nanocomposite nc-TiC/a-C:H films have been investigated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), energy disperse spectroscopy (EDS), microindentation and tribotester measurements. It was observed that the C₂H₂ flow rate significantly affected the Ti content and hardness of films. Furthermore, by selecting the proper value for C₂H₂ flow rate, 20 sccm, one can deposit the nanocomposite film nc-TiC/a-C:H with excellent properties such as superhardness (66.4 GPa), high elastic recovery (83.3%) and high H/E ratio (0.13).     

脉冲偏压电弧离子镀C-N-V薄膜的成分、结构与性能

用脉冲偏压电弧离子镀方法在硬质合金基体上制备了一系列不同成分的C-N-V薄膜.用X射线光电子能谱、激光Raman光谱、 X射线衍射(XRD)、透射电子显微镜(TEM)和纳米压痕等方法分别研究了薄膜的成分、结构与性能.Raman光谱,XRD和TEM结果表明,所制备的薄膜为在类金刚石(DLC)非晶基体上匹配有VN晶体的碳基复合薄膜.随V和N含量的增加,薄膜硬度与弹性模量先增加后下降,在N含量为204%,V含量为218%时薄膜硬度与弹性模量具有最大值,分别为368和5697 GPa,高于相同条件下制备的 关键词： C-N-V薄膜 类金刚石薄膜 纳米复合薄膜 电弧离子镀     

Surface characteristics and nanoindentation study of Ni-Mn-Ga ferromagnetic shape memory sputtered thin films

In present paper, the off-stoichiometric Ni-Mn-Ga ferromagnetic shape memory alloy thin films are fabricated using radio frequency magnetron sputtering method. The compositions, microstructures and mechanical properties of the thin films are characterized by energy dispersive X-ray spectrum (EDAX), X-ray photoelectron spectroscopy (XPS), scanning electronic microscope (SEM), atomic force microscope (AFM) and nanoindentation test, respectively. The results show that there is a thinner layer of oxides consisting of NiO, Ga₂O₃ and an unspecified manganese oxidation (Mn_xO_y) at the surface, whereas a small amount of MnO precipitates exist in internal layers of post-annealed Ni-Mn-Ga thin films. The hardness and elastic modulus decrease with increasing film thickness. Nanoindentation tests reveal that the hardness and elastic modulus of the films can be up to 5.5 and 155 GPa, respectively. The Ni-Mn-Ga thin films have remarkably improved the ductility of Ni-Mn-Ga ferromagnetic shape memory alloys bulk materials.     

Effect of Chromium on Structure and Tribological Properties of Hydrogenated Cr/a-C:H Films Prepared via a Reactive Magnetron Sputtering System

Hydrogenated Cr-incorporated carbon films(Cr/a-C:H) are deposited successfully by using a dc reactive magnetron sputtering system.The structure and mechanical properties of the as-deposited Cr/a-C:H films are characterized systematically by field-emission scanning electron microscope,x-ray diffraction,Raman spectra,nanoindentation and scratch.It is shown that optimal Cr metal forms nanocrystalline carbide to improve the hardness,toughness and adhesion strength in the amorphous carbon matrix,which possesses relatively higher nano-hardness of 15.7GPa,elastic modulus of 126.8 GPa and best adhesion strength with critical load(L_c) of36 N for the Cr/a-C:H film deposited at CH_4 flow rate of 20 sccm.The friction and wear behaviors of as-deposited Cr/a-C:H films are evaluated under both the ambient air and deionized water conditions.The results reveal that it can achieve superior low friction and anti-wear performance for the Cr/a-C:H film deposited at CH_4 flow rate of 20 sccm under the ambient air condition,and the friction coefficient and wear rate tested in deionized water condition are relatively lower compared with those tested under the ambient air condition for each film.Superior combination of mechanical and tribological properties for the Cr/a-C:H film should be a good candidate for engineering applications.     

Specific features of the determination of the mechanical characteristics of thin films by the nanoindentation technique

The hardness and the elastic modulus of Cu thin films on Si, Ti, Cu, and Al substrates are investigated. It is demonstrated that the use of the Oliver-Pharr method in combination with the technique for evaluating the true hardness makes it possible to determine uniquely the hardness of Cu thin films at different ratios between the hardnesses of the film and the substrate. The elastic modulus of thin films can be correctly measured by the Oliver-Pharr method only in the case where the film and the substrate exhibit identical elastic properties. In order to determine the elastic moduli of films with the use of the parameter P/S ², the film and the substrate should have close values of both the hardness and the elastic modulus.     

Influence of annealing temperature on the structural, optical and mechanical properties of ALD-derived ZnO thin films

ZnO thin films grown on Si(1 1 1) substrates by using atomic layer deposition (ALD) were annealed at the temperatures ranging from 300 to 500 °C. The X-ray diffraction (XRD) results show that the annealed ZnO thin films are highly (0 0 2)-oriented, indicating a well ordered microstructure. The film surface examined by the atomic force microscopy (AFM), however, indicated that the roughness increases with increasing annealing temperature. The photoluminescence (PL) spectrum showed that the intensity of UV emission was strongest for films annealed at 500 °C. The mechanical properties of the resultant ZnO thin films investigated by nanoindentation reveal that the hardness decreases from 9.2 GPa to 7.2 GPa for films annealed at 300 °C and 500 °C, respectively. On the other hand, the Young's modulus for the former is 168.6 GPa as compared to a value of 139.5 GPa for the latter. Moreover, the relationship between the hardness and film grain size appear to follow closely with the Hall-Petch equation.     

磁控溅射(Ti,N)/Al纳米复合薄膜的微结构和力学性能

采用Al和TiN靶通过磁控共溅射方法, 制备了一系列Ti:N≈1的不同(Ti, N) 含量的铝基纳米复合薄膜, 利用X射线能量分散谱仪、X射线衍射仪、透射电子显微镜和纳米力学探针表征了薄膜的成分、 微结构和力学性能, 研究了(Ti, N)含量对复合薄膜微结构和力学性能的影响. 结果表明: Ti, N原子的共同加入使复合薄膜形成了同时具有置换固溶和间隙固溶特征的"双超过饱和固溶体", 薄膜的晶粒随着溶质含量的增加逐步纳米化, 并进一步形成非晶结构, 晶界区域形成溶质原子的富集区. 相应地, 复合薄膜的硬度在含1.8 at.%(Ti, N) 时就可迅速提高到3.9 GPa; 随着TiN含量的增加, 薄膜的硬度进一步提高到含17.1 at.%(Ti, N)时的8.8 GPa. 以上结果显示出Ti和N"双超过饱和固溶"对Al薄膜极其显著的强化效果.     

Adjusting chemical bonding of hard amorphous CSixNy thin films by N*-plasma-assisted pulsed laser deposition

Hard amorphous carbon silicon nitride thin films have been grown by pulsed laser deposition (PLD) of various carbon silicon nitride targets by using an additional nitrogen RF plasma source on [100] oriented silicon substrates at room temperature. The influence of the number of laser shots per target site on the growth rate and film surface morphology was studied. Up to about 30 at. % nitrogen and up to 20 at. % silicon were found in the films by Rutherford backscattering spectroscopy (RBS) and X-ray photoelectron spectroscopy (XPS). The XPS of the films showed a clear correlation of binding energy to the variation of PLD parameters. The films show a universal hardness value up to 23 GPa (reference value for silicon substrate 14 GPa) in dependence on target composition and PLD parameters. The results emphasise the possibility of variation of chemical bonding and corresponding properties, such as nanohardness, of amorphous CSi_xN_y thin films by the plasma-assisted PLD process.     

Hydrogenated amorphous carbon thin films deposited by plasma-assisted chemical vapor deposition enhanced by electrostatic confinement: structure,properties, and modeling

Hydrogenated amorphous carbon (a-C:H) is a state-of-the-art material with established properties such as high mechanical resistance, low friction, and chemical inertness. In this work, a-C:H thin films were deposited by plasma-assisted chemical vapor deposition. The deposition process was enhanced by electrostatic confinement that leads to decrease the working pressure achieving relative high deposition rates. The a-C:H thin films were characterized by elastic recoil detection analysis, Rutherford backscattering spectroscopy, scanning electron microscopy, Raman spectroscopy, and nanoindentation measurements. The hydrogen content and hardness of a-C:H thin films vary from 30 to 45 at% and from 5 to 15 GPa, respectively. The hardness of a-C:H thin films shows a maximum as a function of the working pressure and is linearly increased with the shifting of the G-peak position and I _D/I _G ratio. The structure of a-C:H thin films suffers a clustering process at low working pressures. A physical model is proposed to estimate the mean ion energy of carbonaceous species arriving at the surface of a-C:H thin films as a function of processing parameters as pressure and voltage and by considering fundamentals scattering events between ion species and neutral molecules and atoms.     

Synthesis of composite TiN/Ni3N/a-Si3N4 thin films using the plasma focus device

Composite films of TiN/Ni₃N/a-Si₃N₄ were synthesized using the Mather-type plasma focus device with varying numbers of focus deposition shots (5, 15, and 25) at 0° and 10° angular positions. The composition and structural analysis of these films were analyzed by using Rutherford backscattering (RBS) and X-ray diffraction (XRD). Scanning electron microscope and atomic force microscope were used to study the surface morphology of films. XRD patterns confirm the formation of composite TiN/Ni₃N/a-Si₃N₄ films. The crystallite size of TiN (200) plane is 11 and 22 nm, respectively, at 0° and 10° angular positions for same 25 focus deposition shots. Impurity levels and thickness were measured using RBS. Scanning electron microscopy results show the formation of net-like structures for multiple focus shots (5, 15, and 25) at angular positions of 0° and 10°. The average surface roughness of the deposited films increases with increasing focus shots. The roughness of the film decreases at higher angle 10° and the films obtained are smoother as compared with the films deposited at 0° angular positions.     

High strain rate sensitivity of hardness in quinary Ti-Zr-Hf-Cu-Ni high entropy metallic glass thin films

Quinary Ti-Zr-Hf-Cu-Ni high-entropy metallic glass thin films were produced by magnetron sputter deposition. Nanoindentation tests indicate that the deposited film exhibits a relatively large hardness of 10.4±0.6 GPa and a high elastic modulus of 131±11 GPa under the strain rate of 0.5 s⁻¹. Specifically, the strain rate sensitivity of hardness measured for the thin film is 0.05, the highest value reported for metallic glasses so far. Such high strain rate sensitivity of hardness is likely due to the high-entropy effect which stabilizes the amorphous structure with enhanced homogeneity.     

Experimental and numerical approach on interfacial properties of W/Al bilayer films for electronic devices manufacturing

The aim of this article is to provide a systematic method for performing experimental tests and theoretical evaluations on interfacial adhesion properties of the W/Al bilayer thin films interface. Samples W/Al bilayer thin films assembly is deposited on the quartz glass by using radio frequency magnetron sputtering. Based on the analysis of the experimental indentation data, the elastic modulus and hardness of the sample are investigated. The test results show that both of the values are easily influenced by the indentation depth. At the meantime, a finite element model is built to simulate the interface mechanical properties. The analysis shows that stress is mainly centralized close to the indenter and the maximum stress occurs in the lower layer Al film, not in the upper W film. The comparison between the experiment and the simulation shows the validity of the test and the modeling of each other to a certain extent. The investigation builds a basis for future work such as the fabrication of W/Al bilayer thin films for micro/nano manufacturing.     

Nanoindentation of hydrogenated amorphous silicon

Nanoindentation was carried out on thin films of hydrogenated amorphous silicon (a-Si:H) prepared by plasma-enhanced chemical vapor deposition. The composite values of elastic (Young's) modulus, E _c, and hardness, H _c, of the film/substrate system were evaluated from the load–displacement curves using the Oliver–Pharr approach. The film-only parameters were obtained employing the extrapolation of the depth profiles of E _c and H _c. Scanning probe microscopy was employed to image the nanoindenter impressions and to estimate the effect of film roughness and material pile-up on the testing results. It was established that the elastic modulus of thin a-Si:H films is in the range 117–131 GPa, which is lower than for crystalline silicon. In contrast, the values of hardness are in the range 12.2–12.7 GPa, which is comparable to crystalline silicon and higher than for hydrogen-free amorphous silicon. It is suggested that the plastic deformation of a-Si:H proceeds through plastic flow and it is the presence of hydrogen in the amorphous matrix that leads to a higher hardness.     

A measurement of elastic moduli for tungsten films on polymer substrate using wrinkling analysis

The elastic moduli of ultra thin tungsten (W) films on polymers were assessed with wrinkling analysis. Thin W films with a range of thickness between 17 and 100 nm were deposited on compliant polymers and Si strips using DC magnetron sputtering method, causing the tensile stress in a few GPa scale with respect to the thickness of W films. By applying lateral compression on polymer, wrinkle patterns were developed in the W thin film with well-defined amplitude and wavelength. Using a simple equation on wrinkle analysis, the range of elastic moduli was estimated with increasing the thickness. It was found that the elastic modulus and the tensile stress decreased with increasing the film thickness.     

衬底温度对类金刚石薄膜力学性能的影响

 采用脉冲激光沉积方法在不同衬底温度下制备了最高硬度与弹性模量分别达45 GPa和290 GPa,且表面十分光滑的类金刚石薄膜。在相对湿度为80%的条件下,薄膜最低的摩擦系数与磨损率分别为0.045与5.74×10^-10 mm³·N^-1·m^-1。实验结果表明,硬度与弹性模量随衬底温度升高而降低,摩擦系数与磨损率随衬底温度升高而增大。拉曼光谱表明:在室温下制备的薄膜为典型类金刚石结构,sp³含量高达76.8%,而随温度升高,薄膜结构逐渐经无定形碳结构向纳米晶石墨结构方向发展,sp³含量也随之降低,力学性能变差。     

掺硅类金刚石膜的制备与力学性能研究

用脉冲电弧离子镀技术,通过调整掺硅石墨靶和纯石墨靶的数量,制备了一系列不同硅含量的类金刚石薄膜样品.研究发现：当硅含量达6.7at.%时,类金刚石薄膜的应力从4.5GPa降低到3.1GPa,薄膜的硬度还保持在3600Hv,和没有掺杂的类金刚石薄膜的硬度相比,基本保持不变;当硅含量小于6.7at.％时薄膜的摩擦系数相对于未掺杂的类金刚石薄膜也保持不变,为0.15.当薄膜中硅含量继续增加时,薄膜中C—Si键的含量增多,导致薄膜硬度和应力都有较大幅度地减小、摩擦系数增大、磨损性能也变差了. 关键词： 类金刚石膜 掺硅 应力 硬度     

Nanocomposite TiC/a-C：H film prepared on titanium aluminium alloy substrates by PSII assistant MW-ECRCVD

Thin films of titanium carbide and amorphous hydrogenated carbon have been synthesized on titanium aluminium alloy substrates by PSII assisted MW-ECRCVD with a mirror field. The microstructure, chemical composition and mechanical property were investigated. Using XPS and TEM, the films were identified to be a-C：H film containing TiC nanometre grains （namely, the so-called nanocomposite structure）. The size of TiC grains of nanocomposite TiC/DLC film is about 5 nm. The nanocomposite structure has obvious improvement in the mechanical properties of DLC film. The hardness of a-C：H film with Ti is enhanced to 34 G Pa~ while that of a-C：H film without Ti is about 12 G Pa, and the coherent strength is also obviously enhanced at the critical load of about 35N.     

Nanoindentation measurements on modified diamond-like carbon thin films

In the present study, we explored the effect of metallic interlayers (Cu and Ti) and indentation loads (5-20 mN) on the mechanical properties of plasma produced diamond-like carbon (DLC) thin films. Also a comparison has been made for mechanical properties of these films with pure DLC and nitrogen incorporated DLC films. Introduction of N in DLC led to a drastic decrease in residual stress (S) from 1.8 to 0.7 GPa, but with expenses of hardness (H) and other mechanical properties. In contrast, addition of Cu and Ti interlayers between substrate Si and DLC, results in significant decrease in S with little enhancement of hardness and other mechanical properties. Among various DLC films, maximum hardness 30.8 GPa is observed in Ti-DLC film. Besides hardness and elastic modulus, various other mechanical parameters have also been estimated using load versus displacement curves.