Microstructure and magnetron sputtering properties of tungsten target fabricated by low pressure plasma spraying

Planar and rotary tungsten targets were fabricated by low pressure plasma spraying (LPPS). Relative density, oxygen content by mass, microstructure, micro-hardness and ultimate tensile strength (UTS) of LPPS tungsten targets were all influenced by vacuum pressure. Compared with 1.3 × 10⁴ Pa and 6.5 × 10⁴ Pa, a vacuum pressure of 3.9 × 10⁴ Pa was optimal for preparing high-quality tungsten targets. Oxygen content by mass, porosity, average grain size, micro-hardness and UTS of LPPS target fabricated under 3.9 × 10⁴ Pa were about 0.18%, 2.8%, 0.9 μm, 377.8HV_0.025 and 201.1 MPa, respectively. Electron backscattered diffraction (EBSD) from the LPPS sample (fabricated under 3.9 × 10⁴ Pa) showed that proportions of 〈001〉, 〈011〉 and 〈111〉 oriented grains were 10.6%, 21.0% and 12.3% of the total, respectively. The tungsten target possessed excellent magnetron sputtering performance since most tungsten grains with a size <1.0 μm were irregularly distributed without preferred orientation. Rapid sputtering and uniform thinning on the surface of LPPS tungsten targets took place with nano-scaled sputtering pits being formed during magnetron sputtering. Smooth and continuous tungsten thin films with thickness about 320 nm can be deposited by magnetron sputtering from the LPPS samples. XRD spectra of tungsten thin films with body centered cubic structure showed that the intensity of the (110) diffraction peak was much higher than those of the (200), (211) and (220) peaks.     

An investigation of the structural and thermodynamic properties of polystyrene fullerene-containing films

Polystyrene films doped with small additives of fullerenes (w = 0–1 × 10^?3) are obtained. The nonmonotonic dependence of the glass transition point on composition with a minimum at w = 1 × 10^?4 is revealed by the DSC method. It is concluded that there is a plasticizing action of small amounts of filler at w < 1 × 10^?4 and domination of the effect of intermolecular interactions of fullerene with polystyrene at w > 1 × 10^?4. It is established by small-angle X-ray scattering that composites containing fullerenes in the amount w > 1 × 10^?4 are characterized by the greatest mobility of the segments in the modified polymer chains.     

不同氮分压下磁控溅射ZrN对钛/瓷结合的影响

探讨不同氮分压下磁控溅射氮化锆(ZrN)涂层对纯钛与低熔瓷粉(Vita钛瓷粉系统)结合强度的影响。60个纯钛基片随机分为1个对照组和3个实验组。实验组分别在不同氮分压下(Ta组1.0×10-2Pa,Tb组5.0×10-2Pa和Tc组10.0×10-2Pa)溅射沉积ZrN涂层。纯钛试样经表面处理后在烤瓷炉中进行烧结。用XRD检测到ZrN立方新相。万能试验机测试钛瓷试样三点抗弯强度,对照组为(26.67±0.88)MPa,实验组分别为:Ta(49.41±0.55)MPa,Tb(54.55±0.69)MPa和Tc(46.24±0.53)MPa,四组间差别均有统计学意义(P<0.05)。SEM观察表明,实验组钛/瓷结合良好,钛基底残留的瓷断面数量较多,面积较大。不同氮分压下溅射沉积的ZrN涂层对钛/瓷结合的增强程度有所不同,5.0×10-2Pa下钛/瓷结合增强最为明显。     

Effect of annealing on properties of lithium aluminum germanium phosphate electrolyte thick films prepared by aerosol deposition

Li_1.5[Al_0.5Ge_1.5(PO₄)₃] glass-ceramic powder was used for the deposition of thick films on silicon substrate by aerosol deposition. The deposited films were annealed at 873 K and 1023 K for 6 h in air. The thickness of the films was 10–12 m and the relative density was 78%–82%. As-deposited films had nano-scale grains and amorphous regions while in the annealed films, the grain growth and improved crystallinity were observed. The grain size was increased from 12 nm to 25 nm and 97 nm after annealing at 873 K and 1023 K, respectively. The ionic conductivity of the as-deposited film was 8.49 × 10^?9 S cm^?1, which increased to 1.06 × 10^?5 S cm^?1 and 1.16 × 10^?4 S cm^?1 after annealing at 873 K and 1023 K, respectively. The increased ionic conductivity is explained in terms of the increased grain size as well as the improved crystallinity.     

Effect of oxygen vacancy and Mn-doping on electrical properties of Bi4Ti3O12 thin film grown by pulsed laser deposition

An amorphous Bi₄Ti₃O₁₂ phase was formed when films were grown at <400 °C while Bi₂Ti₂O₇ and Bi₂Ti₄O₁₁ transient phases were developed when films were grown at 400–500 and 600 °C, respectively. A homogeneous Bi₄Ti₃O₁₂ crystalline phase was formed in the film grown at 700 °C. The high leakage current density (5 × 10^?7 A cm^?2 at 0.2 MV cm^?1) of the film grown at 300 °C under 100 mTorr oxygen partial pressure (OPP) decreased to 2 × 10^?8 A cm^?2 for the film grown at 200 mTorr OPP, due to the decreased number of intrinsic oxygen vacancies. However, when OPP exceeded 200 mTorr, the electrical properties were deteriorated due to the formation of oxygen interstitial ions. Mn-doping at a suitable level improved the electrical properties of the films by producing extrinsic oxygen vacancies that reduced the number of intrinsic oxygen vacancies. Schottky emission was suggested as the leakage current mechanism of the Bi₄Ti₃O₁₂ film.     

Properties of multilayer gallium and aluminum doped ZnO(GZO/AZO) transparent thin films deposited by pulsed laser deposition process

Multilayer gallium and aluminum doped ZnO (GZO/AZO) films were fabricated by alternative deposition of Ga-doped zinc oxide(GZO) and Al-doped zinc oxide(AZO) thin film by using pulsed laser deposition(PLD) process. The electrical and optical properties of these GZO/AZO thin films were investigated and compared with those of GZO and AZO thin films. The GZO/AZO (1:1) thin film deposited at 400 °C shows the electrical resistivity of 4.18×10^?4 ωcm, an electron concentration of 7.5×10²⁰/cm³, and carrier mobility of 25.4 cm²/(V·s). The optical transmittances of GZO/AZO thin films are over 85%. The optical band gap energy of GZO/AZO thin films linearly decreases with increasing the Al ratio.     

Effects of oxygen pressure on electrical properties of (Na0.5K0.5)NbO3 films grown on Pt/Ti/SiO2/Si substrates

(Na_0.5K_0.5)NbO₃ (NKN) films were annealed under various oxygen partial pressures (OPPs), and the effect of the OPP on the electrical properties of the NKN films was investigated. The dielectric and piezoelectric constants of the NKN film were not influenced by the OPP. However, the remnant polarization and coercive field decreased when the OPP exceeded 25.0 torr because of the low breakdown field and high leakage current. The NKN film annealed under air atmosphere exhibited a high leakage current density that decreased with increasing OPP because of the decreased number of oxygen vacancies. The minimum leakage current density of 3.7 × 10^?8 A cm^?2 at 0.3 MV cm^?1 was obtained for the NKN film annealed under an OPP of 25.0 torr. The leakage current increased when the OPP exceeded 25.0 torr because of the formation of oxygen interstitial ions. The leakage current of the Pt/NKN/Pt device was explained by Schottky emission. The obtained Schottky barrier height between the Pt electrode and NKN film was ～1.24 eV.     

Preparation and characterization of ZnO/Cu/ZnO transparent conductive films

ZnO/Cu/ZnO transparent conductive thin films were prepared by RF sputtering deposition of ZnO target and DC sputtering deposition of Cu target on n-type (001) Si and glass substrates at room temperature. The morphology, structure, optical, and electrical properties of the multilayer films were characterized by field emission scanning electron microscope (FESEM), X-ray diffraction (XRD), UV/Vis spectrophotometer, and Hall effect measurement system. The influence of Cu layer thickness and the oxygen pressure in sputtering atmosphere on the film properties were studied. ZnO/Cu/ZnO transparent conductive film fabricated in pure Ar atmosphere with 10 nm Cu layer thickness has the best performance: resistivity of 2.3×10-4 Ω·cm, carrier concentration of 6.44×1016cm-2 , mobility of 4.51cm2·(V·s)-1 , and acceptable average transmittance of 80 % in the visible range. The transmittance and conductivity of the films fabricated with oxygen are lower than those of the films fabricated without oxygen, which indicates that oxygen atmosphere does not improve the optical and electrical properties of ZnO/Cu/ ZnO films.     

射频磁控溅射沉积TiAlN薄膜的电阻率温度系数(英文)

TiAlN薄膜是一种有可能作为喷墨打印头中传统的TaN或TaAl发热电阻的替代品。采用TiN和AlN作靶材,在400°C下用射频磁控溅射共沉积方法在Si(100)基底上制备TiAlN薄膜,研究了磁控溅射沉积时等离子体功率密度对TiAlN薄膜电阻率温度系数和抗氧化性能的影响。结果表明,TiAlN薄膜的结晶度、晶粒尺寸和表面粗糙度随着等离子体功率密度的增加而增大,从而导致大晶粒和小晶界。X射线光电子能谱分析得到的Ti、Al和N的键合能表明,TiAlN中氮素化学计量学亏缺使TiAlN薄膜的电阻更大。在最高等离子体功率密度下制备的TiAlN薄膜具有最高的抗氧化性能和最低的电阻率温度系数(765.43×106K1)。     

Temperature-Dependent Properties of Spray-Deposited ITO Thin Films

Sprayed indium tin oxide (ITO) thin films are synthesized by mixing adequate quantities of ethanolic solutions of indium trichloride and stannic chloride at different substrate temperatures. The pyrolytic decomposition temperature affects the properties and morphology of ITO samples. X-ray diffraction results showed that the films are polycrystalline with cubic structure and exhibit preferential orientation along (222) plane. The SEM and AFM studies indicated that the surface morphology of the samples increases with substrate temperature. The typical I₅₀₀ sample is composed of cubic grains and has carrier concentration of 3.26 × 10²⁰ cm^?3 and mobility of 9.77 cm²/V s. The electrical resistivity of ITO films decreased with increasing deposition temperature. The highest figure of merit of film is 4.4 × 10^?3 Ω^?1. Optical absorption studies reveal that films are highly transparent in the visible region and band gap increases with substrate temperature owing to Moss-Burstein effect.     

Epitaxial SrRuO3 thin films deposited on SrO buffered-Si(001) substrates for ferroelectric Pb(Zr0.2Ti0.8)O3 thin films

SrRuO₃ thin film electrodes are epitaxially grown on SrO buffered-Si(001) substrates by pulsed laser deposition. The optimum conditions of the SrO buffer layers for epitaxial SrRuO₃ films are a deposition temperature of 700 °C, deposition pressure of 1 × 10^?6 Torr, and thickness of 6 nm. The 100 nm thick-SrRuO₃ bottom electrodes deposited above 650 °C on SrO buffered-Si (001) substrates have a rms (root mean square) roughness of approximately 5.0 Å and a resistivity of 1700 µω-cm, exhibiting an epitaxial relationship. The 100 nm thick-Pb(Zr_0.2Ti_0.8)O₃ thin films deposited at 575 °C have a (00l) preferred orientation and exhibit 2P_r of 40 µC/cm², E_c of 100 kV/cm, and leakage current of about 1 × 10^?7 A/cm² at 1 V. The silicon oxide phase which presents within PZT and SrRuO₃ films, influences the crystallinity of the PZT films and the resistivity of the SrRuO₃ electrodes.     

Effect of working pressure and temperature on ZnO film deposited on free-standing diamond substrates

The structure characteristic and electric performance of ZnO film deposited on nucleation side of free-standing diamond substrates under different heating temperatures (T_h) of substrate and working pressures (p) were studied. The structure of the ZnO films tested by X-ray diffraction shows that ZnO film of high c-axis orientation is deposited on the nucleation side of free-standing diamond substrate which is extremely smooth when T_h=250 °C and p=0.4 Pa. After annealing at 480 °C in N₂ atmosphere, the SEM and the AFM analyses demonstrate that the c-axis orientation of ZnO film is obviously enhanced. The resistivity of ZnO films also increases up to 8×10⁵ Ωcm which is observed by I–V test.     

Low-energy ion beam treatment of α-Al<Subscript>2</Subscript>O<Subscript>3</Subscript>(0001) and improvement of photoluminescence of ZnO thin films

A low energy N₂ ^? ion beam impinged on a α-Al₂O₃(0001) single crystal surface in the range of fluence 5×10¹⁵/cm²?1×10¹⁸/cm² at room temperature. After ion bombardment, chemical bonding on the modified sapphire surface was investigated by x-ray photoelectron spectroscopy. Below a fluence of 1×10¹⁵/cm², only a non-bonded N1s peak at the binding energy 398.7 eV was found, but further irradiation up to 2×10¹⁷/cm² induced Al?O?N bonding at around 403 eV. The occurrence of Al?N bonding was identified at ion fluence higher than 5×10¹⁷/cm² at 396.6 eV. II–VI ZnO thin films were grown on an untreated/ion-beam-induced sapphire surface by pulsed laser deposition (PLD) for the investigation of the modified-substrate effect on photoluminescence. The ZnO films grown on modified sapphire containing Al?O?N bonding only, and both Al?O?N and Al?N bonding showed a significant reduction of the peak related to deep-level defects in photoluminescence. These results are explained in terms of the formation of Al?N?O and Al?O?N layers and relaxation of the interfacial strain between Al₂O₃ and ZnO.     

High-repetition rate pulsed laser deposition of ZrC thin films

ZrC thin films were grown on (100) Si substrates by the pulsed laser deposition (PLD) technique using a high-repetition rate excimer laser working at 40 Hz. The substrate temperature during depositions was set at 300 °C and the cooling rate was 5 °C/min. X-ray diffraction investigations showed that the films were crystalline. Films deposited under residual vacuum or 2 × 10^− 3 Pa of CH₄ atmosphere exhibited a (200)-axis texture, while those deposited under 2 × 10^− 2 Pa of CH₄ atmosphere were found to be equiaxed. The surface elemental composition of as-deposited films, analyzed by Auger electron spectroscopy (AES), showed the usual high oxygen contamination of carbides. Once the topmost − 3-5 nm region was removed, the oxygen concentration rapidly decreased, being around 3-4% only in bulk. Scanning electron microscopy (SEM) investigations showed a smooth, featureless surface morphology, corroborating the roughness values below 1 nm (rms) obtained from simulations of the X-ray reflectivity (XRR) curves. From the same simulations we also estimated films mass density values of around 6.32-6.57 g/cm³ and thicknesses that correspond to a deposition rate of around 8.25 nm/min. Nanoindentation results showed a hardness of 27.6 GPa and a reduced modulus of 228 GPa for the best quality ZrC films deposited under an atmosphere of 2 × 10^− 3 Pa CH₄.     

High-Temperature Electrical Insulation Behavior of Alumina Films Prepared at Room Temperature by Aerosol Deposition and Influence of Annealing Process and Powder Impurities

Alumina (Al₂O₃) is a widely used material for highly insulating films due to its very low electrical conductivity, even at high temperatures. Typically, alumina films have to be sintered far above 1200 °C, which precludes the coating of lower melting substrates. The aerosol deposition method (ADM), however, is a promising method to manufacture ceramic films at room temperature directly from the ceramic raw powder. In this work, alumina films were deposited by ADM on a three-electrode setup with guard ring and the electrical conductivity was measured between 400 and 900 °C by direct current measurements according to ASTM D257 or IEC 60093. The effects of film annealing and of zirconia impurities in the powder on the electrical conductivity were investigated. The conductivity values of the ADM films correlate well with literature data and can even be improved by annealing at 900 °C from 4.5?×?10^?12 S/cm before annealing up to 5.6?×?10^?13 S/cm after annealing (measured at 400 °C). The influence of zirconia impurities is very low as the conductivity is only slightly elevated. The ADM-processed films show a very good insulation behavior represented by an even lower electrical conductivity than conventional alumina substrates as they are commercially available for thick-film technology.     

The Sliding Wear and Friction Behavior of M50-Graphene Self-Lubricating Composites Prepared by Laser Additive Manufacturing at Elevated Temperature

M50 steel is widely applied to manufacture aircraft bearings where service lives are mainly determined by the friction and wear behaviors. The main purpose of this study is to investigate the tribological behaviors and wear mechanisms of M50-1.5 wt.% graphene composites (MGC) prepared by laser additive manufacturing (LAM) (MGC-LAM) sliding against Si₃N₄ ball from 25 to 550 °C at 18 N–0.2 m/s. XRD, EPMA, FESEM, and EDS mapping were conducted to understand the major mechanisms leading to the improvement in the sliding behavior of MGC-LAM. The results indicated that MGC-LAM showed the excellent friction and wear performance at 25-550 °C for the lower friction coefficient of 0.16-0.52 and less wear rate of 6.1-9.5 × 10^?7 mm³ N^?1 m^?1. Especially at 350 °C, MGC-LAM obtained the best tribological performance (0.16, 6.1 × 10^?7mm³ N^?1 m^?1). It was attributed to the dense coral-like microstructure, as well as the formed surface lubricating structure which is composed of the upper uniform lubricating film with massive graphene and the underneath compacted layer.     

Effects of atomic layer deposition temperatures on structural and electrical properties of ZnO films and its thin film transistors

Organic-inorganic thin film transistors (OITFTs) with Al/ZnO/PVP structure on Si substrate were fabricated and studied as to their structural and electrical properties. PVP (poly-4-vinylphenol) organic gate insulator was coated on Si substrate by spin coating method. The ZnO was deposited as an active layer by using the atomic layer deposition (ALD) method on PVP/Si substrate at various temperatures ranging from 80 to 140 °C. The structural and electrical properties of ZnO thin films were analyzed by X-ray diffraction and by hall-effect measurement system for optimum process of the OITFT. The grain size and carrier concentration of ZnO films increased, and the resistivity decreased as the deposition temperature increased from 80 to 140 °C. The field effect mobility, on/off current ratio and threshold voltage of OITFTs with ZnO active layer deposited at 100 °C were found to be 0.37 cm²/V·s, 5×10² and 5 V, respectively.     

Effect of nitrogen on tribological properties of amorphous carbon films alloyed with titanium

The article reports on the dependency of friction and wear of a-(Ti,C,N) films on the nitrogen content. The amount of nitrogen N in the film was controlled by partial pressure of nitrogen p_N2 in the Ar + N₂ sputtering gas mixture. It is shown that the incorporation of N in the film results in the increase of (i) the coefficient of friction μ (increases from 0.12 to 0.37), (ii) the coefficient of wear k (increases from 0.16 × 10^?6 to 0.93 × 10^?6 mm³/N m) and the decrease of (i) the film hardness H, (ii) effective Young's modulus E^?, (iii) the elastic recovery W_e of film and (iv) the ratio H/E^?. The changes of μ and k of the a-(Ti,C,N) film correlate well with changes of the film mechanical properties (H and E^?) and its mechanical behavior (W_e, H/E^? and the ratio H³/E^?2) characterizing the film resistance to plastic deformation.     

Heterogeneous recombination of O(3P) atoms on the surface of aluminum in air plasma

Electron paramagnetic resonance is used to study the loss of oxygen atoms on the surface of aluminum in the positive column of a dc glow discharge in the air at gas pressures of 50–400 Pa and discharge currents of 5–100 mA. The probabilities of the recombination of O(³P) atoms are found to vary from 3 × 10^?3 to 3 × 10^?2 depending on the experimental conditions.     

Characteristics of IZSO films deposited by a co-sputtering system

In−Zn−Sn−O films were deposited on a polycarbonate (PC) substrate by a magnetron co-sputtering system using two cathodes (DC, RF) without substrate heating. Two types of ITO targets (target A: doped with 5 wt.% SnO₂, target B: doped with 10 wt.% SnO₂) were used as an In−Sn−O source. The ITO and ZnO targets were sputtered by DC and RF discharges, respectively, and the composition of the In−Zn−Sn−O films was controlled via the power ratio of each cathode. In the case of ITO target A, the lowest resistivity (4.3×10⁻⁴ Ωcm) was obtained for the film deposited at the RF power (ZnO) of 55W. In the case of ITO target B, the lowest resistivity (2.9×10⁻⁴ Ωcm) of the film was obtained at the RF power (ZnO) of 30W, which was attributed to the increase in carrier density. Hall mobility decreased with increasing carrier density, which could be explained by the increase in ionized impurity scattering.