Structural properties of TiN films grown on stainless steel substrates by a reactive radio-frequency sputtering technique at low temperature

TiN thin films were grown on stainless steel substrates by using the reactive radio-frequency magnetron-sputtering technique at relatively low temperature (200°C) using Ti and N₂. The deposition rate of the TiN film increased linearly with increasing applied radio-frequency power, and it decreased with increasing partial-pressure ratio of the N₂ gas to the Ar gas. Scanning electron microscopy (SEM) showed that the surfaces of the TiN films had very smooth morphologies. The TiN thin film had good stoichiometry for a partial-pressure ratio of 0.05. The stoichiometry of the TiN films and the interface qualities of the TiN/stainless steel heterostructures were investigated by Auger electron spectroscopy (AES) measurements. Auger depth profiles indicated that the compositions of the as-grown films consisted of titanium and nitrogen uniformly distributed throughout the films and that the films exhibited smooth interfaces. The interface quality of the TiN films to the stainless steel substrates were improved by annealing. These results indicate that annealed TiN thin films grown on stainless steel substrates hold promise for potential applications in advanced ceramic devices.     

Surface engineering of biomedical metallic materials by plasma-based low-energy ion implantation

Plasma-based low-energy ion implantation, including plasma source ion nitriding/carburizing and plasma source low-energy ion enhanced deposition of thin films, for surface engineering of metallic materials was emerged as low-temperature, low-pressure surface modification technique. Plasma source ion nitriding onto AISI 316L austenitic stainless steel produced a high nitrogen face-centered-cubic phase (γ_N) layer about 10 μm thick at the temperature of 380 °C during 4 h with the high microhardness of HK_0.1 N 22.0 GPa. The microhardness of the nitrided surface from the titanium nitride phase [(Ti, Al, V)N] layer on Ti6Al4V alloy at 750 °C during 4 h achieved up to about HK_0.1 N 15.5 GPa. No pitting corrosion in the Ringer’s solution at 37 °C was detected by electrochemical polarization measurement for the nitrided AISI 316L stainless steel and Ti6Al4V alloy, respectively. Plasma source ion nitriding of the metallic materials provided the engineering surfaces with combined improvement in hardness and corrosion resistance.     

On the interface between iron and thin films of titanium and titanium nitride

Very thin films of TiN and Ti/TiN were prepared by physical vapor deposition on iron at 500°C to investigate the phenomena occurring at the coating/substrate interface during deposition. By means of depth selective Mössbauer spectroscopy, it was found that preliminary depositions of Ti films lead to the formation of α-Fe(Ti) solid solutions. Depending on the amount of deposited Ti, the α-Ti(Fe) solid solution and Fe?Ti intermetallic compounds can form. The influence of interfacial phases on the film adhesion is discussed.     

PIIID复合强化处理轴承钢表面TiN膜层的XPS表征

用等离子体浸没离子注入与沉积(PIIID)复合强化新技术在AISI52100轴承钢基体表面成功合成了硬而耐磨的氮化钛薄膜。膜层表面的化学组成和相结构分别用X射线衍射(XRD)和X射线光电子能谱(XPS)表征;膜层表面的原子力显微镜(AFM)形貌显示出TiN膜结晶完整,结构致密均匀。XRD测试结果表明,TiN在(200)晶面衍射峰最强,具有择优取向。Ti(2p)的XPS谱峰泰勒拟合分析揭示出,Ti(2p_1/2)峰和Ti_2p3/2峰均有双峰出现,表明氮化物中的Ti至少存在不同的化学状态;N(1s)的XPS谱峰在396.51, 397.22和399.01 eV附近出现了三个分峰,分别对应于TiNO_y,TiN和N—N键中的氮原子。结合O(1s)的XPS结果,证实膜层中除生成有稳定的TiN相外,还有少量钛的氧化物和未参与反应的单质氮。整个膜层是由TiN,TiO₂,Ti—O—N化合物和少量单质氮组成的复合体系。     

Growth of TiN films at low temperature

Thermodynamic analysis on growth of TiN films was given. The driving force for deposition of TiN is dependent on original Ti(g)/N(g) ratio and original partial pressure of N(g). TiN films were deposited by ion beam assisted electron beam evaporation system under suitable nitrogen gas flow rate at 523 K while the density of plasma varied with diverse discharge pressure had been investigated by the Langmuir probe. TiN films were characterized by means of Fourier transform infrared absorption spectrum (FTIR), X-ray diffraction (XRD) and observed by means of atom force microscopy (AFM). The results of these measurements indicated preferential TiN(1 1 1) films were deposited on substrate of Si(1 0 0) and glass by ion beam assisted electron beam evaporation system at low temperature, and it was possible for the deposition of TiN films with a preferential orientation or more orientations if the nitrogen gas flow rate increased enough. Sand Box was used to characterize the fractal dimension of surface of TiN films. The results showed the fractal dimension was a little more than 1.7, which accorded with the model of diffusion limited aggregation (DLA), and the fractal dimension of TiN films increased with increase of the temperature of deposition.     

Synthesis of titanium nitride thin films deposited by a new shielded arc ion plating

Thin films of titanium nitride (TiN) were deposited on stainless steel substrates by a modified deposition technique, double-layered shielded arc ion plating with vicarious circular holes (DL-SAIP). The results show that the TiN film with the distance of 10 mm between the double-layered shield plates had the least droplets. The deposition rate of the films prepared with the new technique was more homogeneous than that of all the other shielded arc ion plating. The film/substrate adhesion and microhardness values of the TiN films were higher than 40 N and 18 GPa, respectively. Thus such TiN thin films can be expected in applications.     

Au/TiN复合薄膜制备及其表面增强拉曼光谱研究

表面增强拉曼散射光谱(SERS)已用于环境监测、生物医药、食品卫生等领域,而高活性SERS基底是表面增强拉曼散射光谱技术应用的关键。TiN作为新型等离子材料具有较强的SERS性能,同时化学稳定性及生物相容性较好,但其SERS性能不如贵金属金强。该研究采用氨气还原氮化法和电化学沉积法,在TiN薄膜表面沉积贵金属Au纳米颗粒制备出Au/TiN复合薄膜。在Au/TiN复合薄膜中单质Au和TiN两种物相共存;随着电化学沉积时间延长,TiN薄膜表面单质金纳米颗粒数量逐渐增多,金纳米颗粒尺寸增大,颗粒间距减小。由于金与TiN两者的本征表面等离子共振耦合作用,Au/TiN复合薄膜的共振吸收峰发生了偏移。利用罗丹明6G为拉曼探针分子,对Au/TiN复合薄膜进行SERS性能分析,发现Au/TiN复合薄膜上的R6G探针分子的拉曼峰信号强度随沉积时间延长呈现先增大后减小的规律;当电化学沉积时间为5 min时,R6G拉曼信号峰较高,复合薄膜样品的SERS活性最大。将Au/TiN复合薄膜和Au薄膜分别浸泡在10-3,10-5,10-7,10-8及10-9 mol·L-1 R6G溶液5 min,进行检测限分析,发现Au/TiN复合薄膜检测极限达10-8 mol·L-1,增强因子达到8.82×105,与Au薄膜和TiN薄膜相比,Au/TiN复合薄膜上对R6G探针分子SERS活性最高。这得益于Au/TiN复合膜中表面等离子体产生的耦合效应,使得局域电磁场强度增强,从而引起R6G探针分子拉曼信号增强。通过2D-FDTD模拟电场分布发现Au/TiN,Au及TiN薄膜具有电场增强作用,其中Au/TiN复合薄膜的增强作用尤为显著,这也证实了氮化钛与金纳米颗粒之间存在耦合效应。另外发现TiN与Au之间可能存在电荷转移,促进了4-氨基苯硫酚氧化反应,进而证实了TiN与Au薄膜的协同作用。此外,Au/TiN复合薄膜均匀性较好,相对平均偏差仅为7.58%。由此可见,采用电化学沉积制备的Au/TiN复合薄膜具有作为SERS基底材料的应用潜力。     

金属管件内壁栅极增强等离子体源离子注入的轴向特性研究

栅极增强等离子体源离子注入(GEPSII)一种新的金属管件内壁处理方法，该方法能够均匀地对金属管件内壁进行离子注入，并且能够生成二元金属化合物.在金属管件内轴向放置三块45号钢样品，利用GEPSII方法在金属管件内壁成功生长金黄色氮化钛(TiN)薄膜.结构分析显示TiN主要沿(111)和(200)晶面生长，深度分析显示膜的厚度大约二十几纳米，膜质地均匀且在基底有一定的嵌入深度.电化学腐蚀、硬度、磨擦学分析表明TiN薄膜很好地改善了45号钢的表面性能，并且表现出很高的轴向均匀性. 关键词： 等离子体源离子注入 内表面 氮化钛     

Deposition of TiN Films by Novel Filter Cathodic Arc Technique

A straight magnetic filtering arc source is used to deposit thin films of titanium nitride. The properties of the films depend strongly on the deposition process. TiN films can be deposited directly onto heated substrates in a nitrogen atmosphere or onto unbiased substrates by condensing the Ti^＋ ion beam in about 300 eV N2^＋ nitrogen ion bombardment. In the latter case, the film stoichiometry is varied from an N：Ti ratio of 0.6-1.1 by controlling the arrival rates of Ti and nitrogen ions. Meanwhile, simple models are used to describe the evolution of compressive stress as function of the arrival ratio and the composition of the ion-assisted TiN films.     

Anomalous ion accelerated bulk diffusion of interstitial nitrogen

Interstitial N diffusion under low energy (approximately 700 eV) Ar+ bombardment at 673 K in ion beam nitrided austenitic stainless steel is investigated. Ar+ ion bombardment increases the N mobility in depths far beyond the ion penetration depth, resulting in an increased broadening of the N depth profile as a function of Ar+ flux. This effect cannot be explained by any established mechanism of radiation-enhanced diffusion. An explanation based on quasiparticle-enhanced mobility is proposed.     

Advanced ion energy loss models: Applications to subnanometric resolution elemental depth profiling

In principle, the depth distribution of the different chemical elements near the surface of solids can be determined quantitatively and absolutely with subnanometric depth resolution using medium energy ion scattering (MEIS), which is a refined version of Rutherford backscattering spectrometry (RBS). The energy resolution of current MEIS analyzers reveals spectral features that cannot be resolved using conventional RBS detectors. Thus, the usual data analysis framework based on a standard Gaussian approximation for the ion energy distribution in the target is applicable to regular RBS, but not generally to MEIS, in particular if one aims at subnanometric depth resolution. The observed asymmetry in the ion energy loss distributions is a direct consequence of the asymmetric character of inelastic energy transfers during individual atomic collisions and of the stochastic character of the resulting energy losses. We propose a model that accounts for the proper statistics of the small energy loss events and for an approximate electronic energy loss distribution during the backscattering event. The validity of this model is discussed and applied to the determination of HfO₂ and TiO₂ film thicknesses as well as to detect Al₂O₃ and HfO₂ intermixing. This final application case also illustrates the potentialities as well as some inherent limitations of MEIS. The model developed here has been made available to the public in the form of a software for MEIS data analysis.     

氮流量对磁控溅射法制备氮化钛薄膜光学性能的影响

采用磁控溅射方法在载波片和Al基片上制备了氮化钛薄膜;通过改变N2流量来改变薄膜中N／Ti原子比例。采用分光光度计和扫描隧道显微镜测试手段对氮化钛薄膜光学性能随N2流量变化的规律进行了研究。薄膜反射率光谱和扫描隧道图谱分析表明,氮化钛薄膜主要遵循自由载流子光吸收机制,随着N含量的增加,溥膜中的自由电子数目不断减少,等离子体频率逐渐红移,反射率降低,薄膜颜色发生变化。从薄膜扫描隧道谱（STS）可知,TiN薄膜表现出类似金属的光学性能,并且其禁带宽度Eg=1．64eV。     

Synthesis and magneto-optical properties of nanogranular Co-Ti-O films

Studies of the structural and magneto-optical properties of nanogranular Co-Ti-O films prepared under conditions of the solid-state reaction with oxygen exchange in the CoO/Ti layered structures are presented. The formation of granular films with compositions near or below the percolation threshold is shown. The specific features of the magneto-optical spectra of the prepared films as compared to the spectra of continuous metallic films are revealed.     

Atomic transport and chemical stability during annealing of ultrathin Al2O3 films on Si

Ultrathin films of Al2O3 deposited on Si were submitted to rapid thermal annealing in vacuum or in oxygen atmosphere, in the temperature range from 600 to 800 degrees C. Nuclear reaction profiling with subnanometric depth resolution evidenced mobility of O, Al, and Si species, and angle-resolved x-ray photoelectron spectroscopy revealed the formation of Si-Al-O compounds in near-surface regions, under oxidizing atmosphere at and above 700 degrees C. Under vacuum annealing all species remained essentially immobile. A model is presented based on diffusion-reaction equations capable of explaining the mobilities and reproducing the obtained profiles.     

Brillouin scattering study on the wave properties in thin SiC films

The modified Rayleigh wave velocities on the SiC hetero-epitaxial films have been investigated using a Brillouin scattering technique. The SiC nanoscopic films were formed on clean surface of Si substrates by the molecular ion beam technique or Ion beam induced chemical vapor deposition. Back scattering geometry was used to obtain the ripple Brillouin scattering from the film surface. Owing to the high stability of the measurement system, the precise velocity measurement was performed. As a result, Rayleigh wave velocity showed a clear dependence on the crystalline structure of SiC film, indicating that the shear moduli of very thin epitaxial films shows similar tendency with those of SiC bulk sample.     

Ti/TiN multilayer thin films deposited by pulse biased arc ion plating

In this work, the effect of modulation period (Λ) on Ti/TiN multilayer films deposited on high-speed-steel (HSS) substrates using pulse biased arc ion plating is reported. The crystallography structures and cross-sectional morphology of Ti/TiN multilayer films were characterized by X-ray diffraction analysis (XRD) and scanning electron microscopy (SEM), respectively. Their mechanical properties were determined via nanoindentation measurements, while the film/substrate adhesion via the scratch test. It was found that the highest hardness value reached 43 GPa for the modulation period of 54 nm, while the film/substrate adhesion also reached the highest value of 83 N. Furthermore, the hardness enhancement mechanism in the multilayer films is discussed.     

Properties including step coverage of TiN thin films prepared by atomic layer deposition

The physical properties including the step coverage of the TiN films deposited by atomic layer deposition (ALD) technique, using TiCl₄ and NH₃ as the precursors have been investigated. The deposition rate of the TiN film is constant and moderately high (0.6 Å per cycle) under an optimum deposition condition. The film resistivity is appreciably low (200 μΩ cm). The XRD analysis results indicate polycrystalline nature of the TiN films with a (1 1 1) preferred orientation. The XPS and AES analysis results establish that the Cl impurity concentration in the TiN films is lower than 1 at.% and the ratio of Ti and N by atomic concentration in the TiN films is nearly equal to 1:1 AFM analysis reveals that the RMS surface roughness is low. Also it is found by SEM observation that the step coverage of the TiN films with trenches (the aspect ratio being 10:1) is excellent. One hundred percent conformality is observed for both the side/bottom and the side/top sections.     

Development of laser deposited multilayer zone plate structures for soft X-ray radiation

As a novel approach, the combination of pulsed laser deposition and focused ion beam was applied to fabricate different types of multilayer zone plate structures for soft X-ray applications. For this purpose, high quality non-periodic ZrO₂/Ti multilayers were deposited by pulsed laser deposition on planar Si substrates and on rotating steel wires with layer thicknesses according to the Fresnel zone plate law. Linear focusing optics were fabricated by cutting slices out of the multilayers by focused ion beam and placing them directly over pinholes within Si₃N₄ substrates. Additionally, it was shown that laser deposition of depth-graded multilayers on a wire is also a promising way for building up multilayer zone plates with point focus. First experiments using a table-top X-ray source based on a laser-induced plasma show that the determined focal length and spatial resolution of the fabricated multilayer Laue lens corresponds to the designed optic.     

CEMS of nitride coatings in agressive environments

The corrosion properties of single layered TiN and CrN films have been compared to bi-layered and multi-layered Ti/TiN films. XPS has showed that in humid SO₂ atmosphere the best corrosion properties have been achieved by a multi-layered Ti/TiN coating. Cyclic voltammetry in acetate buffer has been applied to measure the porousity and corrosion resistance of coatings. The best results have been achieved by multi-layered Ti/TiN and CrN films. Conversion electron Mössbauer spectroscopy has been used to study the changes in the interface Fe/TiN during thermal treatment in UHV. It has been shown that the amount of iron nitrides in the interface increases with increasing temperature.     

Comparing the chemical properties of evaporated and sputtered niobium films on oxidized Si(1 0 0) wafers - preparation of oxynitride films

Five hundred nanometers of niobium films have been deposited on silicon(1 0 0) wafers with 100 or 300 nm thermally grown oxide by electron beam evaporation and DC magnetron sputtering. SEM and AFM investigations revealed smaller crystallites and rougher surfaces for the evaporated films. The differences in film morphology resulted in lower reflection intensities in XRD for the as-deposited evaporated films. In order to investigate the influence of the structural properties on their chemical reactivities, in a first set of experiments the films were nitrided with molecular nitrogen by rapid thermal processing (RTP) at varying temperatures. In another set of experiments after nitridation in nitrogen at 1000 °C an oxidation step in molecular oxygen at varying temperatures followed. The films showed different reactivities, leading to different rates of nitridation and oxidation. Sputtered films were less reactive than the evaporated films, deduced from the sequence of reaction products dependent on reaction temperature. XRD data indicated that oxynitrides have formed. Elemental depth profiles were measured by secondary ion mass spectrometry (SIMS).