Filtered vacuum arc deposition of transparent conducting Al-doped ZnO films

Transparent conducting ZnO:Al and ZnO films of 380-800 nm thickness were deposited on glass substrates by filtered vacuum arc deposition (FVAD), using a cylindrical Zn cathode doped with 5-6 at.% Al or a pure Zn cathode in oxygen background gas with pressure P = 0.4-0.93 Pa. The crystalline structure, composition and electrical and optical properties of the films were studied as functions of P. The films were stored under ambient air conditions and the variation of their resistance as function of storage time was monitored over a period of several months.The Al concentration in the film was found to be 0.006-0.008 at.%, i.e., a few orders of magnitude lower than that in the cathode material. However, this low Al content influenced the film resistivity, ρ, and its stability. The resistivity of as-deposited ZnO:Al films, ρ = (6-8) × 10^− 3 Ω cm, was independent of P and lower by a factor of 2 in comparison to that of the ZnO films deposited by the same FVAD system. The ρ of ZnO films 60 days after deposition increased by a factor of ∼ 7 with respect to as-deposited films. The ZnO:Al films deposited with P = 0.47-0.6 Pa were more stable, their ρ first slowly increased during the storage time (1.1-1.4 times with respect to as-deposited films), and then stabilized after 30-45 days.     

Cathodic arc plasma deposited TiAlSiN thin films using an Al-15 at.% Si cathode

Thin films of TiAlSiN were deposited on SKD 11 tool steel substrates using two cathodes, of Ti and Al-15 at.% Si, in a cathodic arc plasma deposition system. The influence of AlSi cathode arc current and substrate bias voltage on the mechanical and structural properties of the films was investigated. The TiAlSiN films had a multilayered structure in which nanocrystalline cubic TiN layers alternated with nanocrystalline hexagonal AlSiN layers. The hardness of the films decreased with the increase of the AlSi cathode arc current. The hardness of the films also decreased as the bias voltage was raised from − 50 V to − 200 V. The maximum hardness of 43 GPa was observed at the films deposited at the pressure 0.4 Pa, Ti cathode arc current 55 A, Al cathode arc current 35 A, temperature 250 °C and bias voltage of − 50 V.     

Properties of SnO2 films fabricated using a rectangular filtered vacuum arc plasma source

Transparent and conducting SnO₂ films of 57–200nm thickness were deposited on microscope glass slide substrates, using a rectangular filtered vacuum arc deposition system. The 40 glass slides were equally distributed on a 400 × 420mm substrate carriage, and were exposed to a Sn plasma beam, produced by a rectangular vacuum arc plasma gun with a Sn cathode, and passed through a rectangular magnetic macroparticle filter towards the substrates. The carriage with the substrates was transported past the 94 × 494mm filter outlet. The SnO₂ films were fabricated on the glass substrates at room temperature by maintaining the chamber oxygen background pressure at 0.52Pa. The film composition, and electrical and optical properties were studied as a function of the film thickness. The films were stored under ambient air conditions, and their electrical resistance was measured as a function of storage time over a period of several months.

The average resistivity of films was 10–17mΩ cm for films with thickness (t) less than 100nm, but that of t > 100nm it was 5–9mΩ cm. The resistivity of the films with t > 100nm did not change significantly after 8months of storage in ambient air. The optical transmittance of the films in the visible spectrum was in the range of 75–90%. The optical constants, i.e., the refractive index and the extinction coefficient of the films at wavelength λ = 550nm were in the range of 2.02–2.09 and 0.013–0.023, respectively, and the optical band gap energy was 4.15–4.21eV. Unlike the electrical resistivity, the optical parameters weakly depended on t.     

柱弧离子镀和非平衡磁控溅射镀制备Ti-N-C黑色硬质膜

采用柱弧离子镀和中频孪生靶非平衡磁控溅射镀膜技术制备了Ti-N-C多层复合黑色硬质膜.采用轮廊仪扫描电子显微镜(SEM)、分光光度计、显微硬度计等手段研究了所得膜层的各项性能.结果表明,两种工艺都可以获得颜色较深的黑色硬质膜,柱弧离子镀制备黑色硬质膜的效率高、力学性能更好;中频孪生靶非平衡磁控溅射制备的黑色硬质膜表面光滑、颜色更深.     

Plasma assisted and manipulated deposition of thin film electrodes for micro batteries

The properties of the thin film electrodes have been the main factors for the performances of lithium or lithium ion micro batteries, i.e. thin film batteries. In this paper, plasma assisted and manipulated techniques have been developed for the fabrication of polycrystalline thin film cathodes, and of amorphous/nano-crystalline thin film anodes. The thin film electrodes were deposited by magnetron sputtering under precisely controlled plasma conditions. The deposition apparatuses were designed to obtain the desired film properties by equipping a long anode-shield or an inductive coil. Polycrystalline LiMn₂O₄ thin film cathodes with a smooth surface were deposited, which greatly reduced the cathode/electrolyte interface resistances. Amorphous/nano-crystalline Sn thin film anodes were obtained free of plasma induced large grains, which enhanced the cycling stability. The results have demonstrated that by careful designs of deposition apparatus the plasma conditions can be precisely controlled and therefore the thin film electrodes of desired properties can be obtained.     

Transparent conducting ZnO thin films deposited by vacuum arc plasma evaporation

A high rate deposition of co-doped ZnO:Ga,F and ZnO-In₂O₃ multicomponent oxide thin films on large area substrates has been attained by a vacuum arc plasma evaporation method using oxide fragments as a low-cost source material. Highly transparent and conductive ZnO:Ga,F and ZnO-In₂O₃ thin films were prepared on low temperature substrates at a deposition rate of approximately 375 nm/min with a cathode plasma power of 10 kW. A resistivity of 4.5×10⁻⁴ Ω cm was obtained in ZnO:Ga,F films deposited at 100 °C using ZnO fragments co-doped with 1 wt.% ZnF₂ and 1 wt.% Ga₂O₃ as the source material. In addition, the stability in acid solution of ZnO films was improved by co-doping. It was found that the Zn/(In+Zn) atomic ratio in the deposited ZnO-In₂O₃ thin films was approximately the same as that in the fragments used. The ZnO-In₂O₃ thin films with a Zn/(In+Zn) atomic ratio of approximately 10-30 at.% deposited on substrates at 100 °C exhibited an amorphous and smooth surface as well as a low resistivity of 3-4×10⁻⁴ Ω cm.     

Optimization of field emission properties of carbon nanotubes cathodes by electrophoretic deposition

Cold cathodes of carbon nanotubes (CNTs) were deposited on the glass substrate by the electrophoretic deposition (EPD) method. The cathodes were tested in the diode construction with the cathode–anode gap of 170 μm in vacuum. The emission characteristics of the CNTs film cathodes have as good properties as those by screen printing and better emission uniformity. The influence of the voltage between electrodes in the electrophoretic process of flat cold cathode fabrication on the uniformity of the CNTs film distribution was studied. The results indicate that the uniformity of CNTs film cathode by EPD depends on the voltage between electrodes during the electrophoretic deposition. The uniformity of CNTs film and optimized emission properties of the cathode have been achieved when the voltage is 25 V.     

Phase determination of filtered vacuum arc deposited TiO2 thin films by optical modeling

Thin films of TiO₂ were produced using filtered vacuum arc deposition. Arc currents were 275, 300, 325 A, and the oxygen pressure during deposition was 0.93 Pa. The substrates were glass microscope slides, at temperatures of 25 °C (RT), 200 °C, and 400 °C. Film thickness was in the range 100 to 250 nm, depending on the deposition conditions. Film structure and chemical composition were determined using XRD and XPS analyses, respectively. As-deposited films were amorphous, except to two samples that were found to be crystalline (deposited with 300 A, 325 A at 400 °C), and the crystalline phase was close to that of anatase. All of the films were partially crystallized by annealing in air at 450 °C for 1 h. The O:Ti atomic concentration ratio was in the range 1.6:1-2:1, independent of deposition conditions. The optical parameters, refractive index and the extinction coefficient of the films were determined using variable angle spectroscopic ellipsometry. In addition, the optical transmission of the films were determined in the UV-VIS and IR regions. The average optical transmission in the VIS spectrum was 70-85%, affected by the interference in the film with 90% maxima and 60% minima. The refractive index at λ = 550 nm was in the range 2.4 to 2.7, depending on the deposition conditions and annealing. Using the semi-empirical model of Wemple and DiDomenico for the dielectric function below the interband absorption edge of ionic and covalent solids, the dispersion energy parameters of TiO₂ (E_o, E_d) were calculated. The underlying structural order of the amorphous films was inferred by comparing the dispersion energy parameters of the amorphous films with those of crystalline TiO₂. As expected, the refractive index of the amorphous films depended on the underlying phase of the film. The optical analyses indicated that the underlying phase of the amorphous films deposited on RT substrates was close to anatase, whereas the underlying phase of the amorphous films deposited on 400 °C substrates and annealed at 450 °C for 1 h consisted of both anatase and rutile. Thus, although the XRD analyses could not indicate the underlying phase of the amorphous films, it could be determined by the optical analyses.     

Fabrication of transparent conducting amorphous Zn-Sn-In-O thin films by direct current magnetron sputtering

Amorphous ZnO-SnO₂-In₂O₃ films were grown by direct current magnetron sputtering from vacuum hot pressed ceramic oxide targets of Zn:In:Sn cation ratios 1:2:1 and 1:2:1.5 onto glass substrates. X-ray diffraction analysis showed that the microstructure remained amorphous during annealing at 200 °C for up to 5 hours. By monitoring the electrical resistivity, oxygen content and substrate temperature were optimized during deposition. The optimal films were characterized by Hall Effect, work function and optical spectroscopy measurements. Films of 1:2:1 composition showed the lowest resistivity (7.6 × 10^− 4 Ω-cm), when deposited onto substrates preheated to 300 °C. Transmissivity of all films exceeded 80% in the visible spectral region. The energy gap was 3.52-3.74 eV, and the work function ranged 5.08-5.22 eV, suitable for cathode applications in organic light emitting diodes. Overall, the film characteristics were comparable or superior to those of amorphous tin-doped indium oxide and zinc-doped indium oxide films and may serve as viable, lower-cost alternatives.     

多元氮化物薄膜及其沉积工艺对NiTi记忆合金性能和组织的影响

采用真空阴极电弧沉积技术,在NiTi记忆合金表面沉积了TiAlBN和TiAlCrFeSiBN多元膜和TiN薄膜,研究了薄膜成份及沉积工艺对NiTi合金性能和组织的影响.结果表明,在NiTi合金表面沉积TiAlBN和TiAlCrFeSiBN多元膜和TiN薄膜均可降低合金在Hank溶液中的Ni溶出速率,其中多元膜的Ni溶出速率最小;提高偏压对沉积了TiAlBN多元膜的NiTi合金的Ni溶出速率无明显影响,但使沉积了TiAlCrFeSiBN膜的NiTi合金的Ni溶出速率降低.在TiAlBN和TiAlCrFeSiBN多元膜表面存在较多细小的钛滴和孔隙,钛滴与薄膜基体之间的融合良好;在TiN薄膜表面存在一些大钛滴和孔隙,钛滴与薄膜基体之间的融合不好.镀膜后,NiTi基体的加热相变点移向低温区,其幅度与薄膜成份及沉积工艺有关,提高偏压使沉积了两种多元膜的NiTi基体的相变点移动幅度增大,但却使沉积了TiN膜的NiTi基体的相变点的移动幅度减小.镀膜过程均使NiTi中的M体尺寸增大.     

阴极弧等离子体沉积NbN薄膜

利用磁过滤等离子体沉积装置，结合金属等离子体积技术，在Si基底上分别用动态离子束增强沉积和非增强沉积的方法来制备NbN膜，对二者予以比较，并探讨了非增强沉积过程中基底温度对NbN膜层的影响，温度升高使膜层中N的含量先呈上升趋势，随后又稍微降低，温度升高促进晶粒生长，使晶粒尺寸变大，从室温到约300℃的温度下得到的薄膜在（220）峰表现出很强的择优取向，500℃的沉积温度下，（220）峰变的很弱，（200）峰表现出择优取向，500℃时膜层中得到单一的δNbN相；表面形貌方面，温度越低，薄膜越不完整，在500℃左右才能得到光滑完整的NbN膜。与非增强沉积相比，增强沉积不需加热，在温下就能得到光滑致密的NbN膜，膜层中N的含量更高，且没有明显的择优取向。     

The role of the Zn buffer layers in the structural and photoluminescence properties of ZnO films on Zn buffer layers deposited by RF magnetron sputtering

Highly c-axis oriented ZnO thin films were grown on Si (100) substrates with Zn buffer layers. Effects of the Zn buffer layer thickness on the structural and optical qualities of ZnO thin films were investigated for the ZnO films with the buffer layers 90, 110, and 130 nm thick using X-ray diffraction (XRD), photoluminescence (PL) and atomic force microscopy (AFM) analysis techniques. It was confirmed that the quality of a ZnO thin film deposited by RF magnetron sputtering was substantially improved by using a Zn buffer layer. The highest ZnO film quality was obtained with a Zn buffer layer 110 nm thick. The surface roughness of the ZnO thin film increases as the Zn buffer layer thickness increases.     

Surface characterization of sol-gel derived indium tin oxide films on glass

Indium tin oxide (ITO) films containing different In : Sn atomic ratios, viz. 90 :10, 70 :30, 50 : 50, 30 :70, were deposited on two types of glass substrates by sol-gel spinning technique. XPS analysis of the films was done under as-received and after-sputtering conditions. The narrow spectra obtained for the Na1s, In3d, Sn3d and O1s have been discussed. Oxygen was found to exist in three chemical environments in as-received samples due to the existence of (i) environmental hydroxyl (-OH) group, (ii) crystalline ITO and (iii) amorphous ITO; but it was in two chemical environments, (ii) and (iii), after surface cleaning by sputtering. The presence of both tin metal and tin oxides was confirmed by the peak analysis of Sn3d. The In : Sn atomic ratio taken in the precursor sols did not change considerably in the case of developed films of low Sn content, but considerable change was observed in the films having high Sn content.     

Structural analysis of Ti-Fe thin films prepared by pulsed laser deposition

Titanium iron oxide (Ti-Fe-O) thin films have been successfully deposited by pulsed laser deposition (PLD). Experiments were carried out by using some targets. One was a Ti-50 at.% Fe-sintered target, while the others were Ti and Fe plates with various surface area ratio [S_R=S_Fe/(S_Fe+S_Ti)] from 30 to 70%. The thin films were analyzed by X-ray diffractometry, Rutherford backscattering spectroscopy (RBS) and transmission electron microscopy (TEM). From XRD analysis, the main phase in the thin films deposited at S_R=30 and 50% was β-Ti (Fe). By increasing S_R to 70%, the main phase of the thin film changed to TiFe. By phase diagram, composition of TiFe must be between Ti-47.5-50.3 at.% Fe at a temperature of 1085 °C. However, the composition of the thin film deposited at S_R=70% was found to be Ti_0.15Fe_0.62O_0.23. Thus, the composition of Fe in the thin film was much greater than the solubility limit. This fact suggests two possibilities. One is that the thin films, which we have deposited, were in a metastable state. The other is that metal oxides of amorphous state could be contained in the thin film.     

采用真空电弧源镀制纳米TiO2薄膜研究

在真空条件下利用真空电弧源在不同基底材料上镀制了TiO2薄膜.对影响镀膜过程和膜层质量的氧气工作压强和偏压等因素进行了研究.X射线衍射结构分析结果显示TiO2薄膜主要以锐钛矿相为主及少量的金红石相.对TiO2薄膜的物理性质、化学性质进行了初步检测.     

The structural and electrical properties of Zn-Sn-O buffer layers and their effect on CdTe solar cell performance

Thin films of zinc-tin-oxide (ZTO) have been deposited on SnO₂:F coated glass substrates by co-sputtering of SnO₂ and ZnO. The deposition conditions for ZTO were controlled in order to vary film stoichiometry. The electro-optical and structural properties of ZTO have been studied as a function of their stoichiometric ratio and post-deposition annealing conditions. The same films were subsequently utilized as part of a bi-layer transparent front contact for the fabrication of CdTe solar cells: glass/SnO₂:F/ZTO. The performance of these devices suggested that the ZTO deposition and cell processing conditions can be optimized for enhanced device performance in particular for devices with thin CdS. Specifically, high blue spectral response (> 70% at 450 nm), accompanied by high open-circuit voltages (830 mV), and fill factors (70⁺%) have been demonstrated. Best solar cell performance was obtained for multi-phase ZTO films deposited at substrate temperatures of 400°C and a Zn/Sn ratio of 2.0, and which contained the binary phase of ZnO₂.     

The effect of Sn concentration on some physical properties of zinc oxide films prepared by ultrasonic spray pyrolysis

The effect of Sn concentration on zinc oxide (ZnO) film properties has been investigated by depositing films with various Sn concentrations in the solution (Sn/Sn + Zn ratio from 0 to 50 at%) at a substrate temperature of 350°C by ultrasonic spray pyrolysis (USP) technique. The deposited films were characterized for their electrical, structural, morphological and elemental properties using current-voltage and conductivity-temperature measurements, X-ray diffraction, scanning electron microscopy and energy dispersive X-ray spectroscopy. Electrical investigations showed that the resistivity of ZnO films decreases for lower Sn concentration (at 10%) and then increases for higher Sn concentration (at 30–50%). Also, depending on the increasing Sn concentration, energies of donor-like traps for ZnO films decreased and activation energy of donors for ZnO films increased. The XRD patterns showed that the as-deposited films have polycrystalline structure and the crystalline nature of the films was deteriorated with increasing Sn concentration and a shift to amorphous structure was seen. The effect of Sn concentration was to increase the surface roughening and change considerably the morphologies of ZnO films. The most homogenous surface was seen in ZnO films. EDS results showed that all elements in the starting solutions were in the solid films and Zn element is more dominant than Sn on the surfaces. After all investigations, it was determined that Sn incorporation dramatically modifies the properties of ZnO films. ZnO and ZnO:Sn (10 at%) films have a low resistivity and high transparency in the visible range and may be used as window material and antireflecting coating in solar cells while the other films may be used in gas sensors where high conductivity is unnecessary.     

Sputtering of ZnO:Al films from dual tube targets with tilted magnetrons

Aluminum doped zinc oxide (ZnO:Al) films were deposited by mid-frequency sputtering rotating tube targets at high discharge powers in a double cathode system. The magnetrons located inside the tube targets were tilted by ± 30°, leading to different racetrack orientations. Deposition rate and electrical properties of statically deposited films were investigated. Different properties of ZnO:Al films show lateral variations corresponding to the racetrack positions, which shift according to the tilt angles of double magnetrons. The highest average static deposition rate and the corresponding dynamic value were up to 360 nm/min and 111 nm m/min, respectively, for magnetrons tilted towards the center of the cathodes. The material properties of the ZnO:Al film prepared in dynamic mode were found to behave like the superpositions of properties of static films at different positions. Upon wet chemical etching in diluted hydrochloric acid (HCl), the surfaces of sputtered ZnO:Al films became rough, and three typical surface structures were observed and identified on statically deposited ZnO:Al films. The related plasma physics, growth and chemical etching mechanisms were discussed.     

Synthesis of aluminum nitride thin films by filtered arc ion plating deposition

Thin films of aluminum nitride (AlN) were deposited on stainless steel and glass substrates by a modified deposition technique, filtered arc ion plating, at an enhanced deposition rate. X-ray diffraction spectra confirmed the exclusive presence of AlN hexagonal wurtzite phase. Under a mixed gas (Ar + N₂) pressure of 0.90 Pa and a bias voltage of − 400 V, the deposited films exhibited a fairly low surface roughness of 2.23 nm. The thin films were proved higher than 75% transparent in the visible spectral region. The bonding strength between the film and substrate was verified higher than 20 N. Thus high performance of such AlN thin films can be expected in applications.     

Modification of low temperature deposited LiMn2O4 thin film cathodes by oxygen plasma irradiation

Lithium manganese oxides have been deposited by radio frequency magnetron sputter deposition with relatively lower annealing temperatures and then post-treated with a radio frequency (rf) driven oxygen plasma. Following oxygen plasma irradiation, the film properties were modified, and the performance of the thin film cathode has been enhanced. The electrochemical properties of the treated thin-film cathodes were characterized and compared. The results showed that the samples with moderate plasma treatment also maintained good cyclic properties as cycled at a wide range potential window of 2.0 V-4.5 V. Its electrochemical properties were significantly improved by this process, even though the films were prepared under low annealing temperature.