Influence of deposition temperature on the growth of vacuum evaporated V2O5 thin films

V₂O₅ films were deposited on silicon (111) substrates by vacuum evaporation technique at various deposition temperatures of 300, 473, 573, 623 and 673 K. X-ray characterization revealed that the films deposited at T_s≤473 K are amorphous and the film deposited at T_s≥573 K is polycrystalline. It is interesting to note that the film deposited at T_s=573 K is strongly oriented with (001) planes parallel to the substrate and the degree of preferred orientation towards (001) planes found to decrease with further increase in the deposition temperature. The influence of deposition temperature on the growth of the V₂O₅ films has been studied by Raman scattering spectroscopy. The films deposited on the silicon substrates maintained at 573 K are found to have better structural quality.     

Annealing dependence of residual stress and optical properties of TiO2 thin film deposited by different deposition methods

Titanium oxide (TiO(2)) thin films were prepared by different deposition methods. The methods were E-gun evaporation with ion-assisted deposition (IAD), radio-frequency (RF) ion-beam sputtering, and direct current (DC) magnetron sputtering. Residual stress was released after annealing the films deposited by RF ion-beam or DC magnetron sputtering but not evaporation, and the extinction coefficient varied significantly. The surface roughness of the evaporated films exceeded that of both sputtered films. At the annealing temperature of 300 degrees C, anatase crystallization occurred in evaporated film but not in the RF ion-beam or DC magnetron-sputtered films. TiO(2) films deposited by sputtering were generally more stable during annealing than those deposited by evaporation.     

蒸发速率对ZnS薄膜性能的影响

为了研究蒸发速率对ZnS薄膜的折射率、表面形貌和应力等性能的影响,本文采用电子束蒸发技术进行了ZnS薄膜的制备.首先在K9玻璃基片上镀制薄膜,采用分光光度计进行透射率曲线的测试,利用光谱反演法得出薄膜的折射率,采用原子力显微镜表征了样品的表面形貌.最后在聚酰亚胺基底上镀制薄膜,利用Stoney公式计算出薄膜的应力.结果...     

Effects of annealing on the optical, structural, and chemical properties of TiO2 and MgF2 thin films prepared by plasma ion-assisted deposition

Effects of thermal annealing at 400 degrees C on the optical, structural, and chemical properties of TiO2 single-layer, MgF2 single-layer, and TiO2/MgF2 narrow-bandpass filters deposited by conventional electron-beam evaporation (CE) and plasma ion-assisted deposition (PIAD) were investigated. In the case of TiO2 films, the results show that the annealing of both CE and PIAD TiO2 films increases the refractive index slightly and the extinction coefficient and surface roughness greatly. Annealing decreases the thickness of CE TiO2 films drastically, whereas it does not vary that of PIAD TiO2 films. For PIAD MgF2 films, annealing increases the refractive index and decreases the extinction coefficient drastically. An x-ray photoelectron spectroscopy analysis suggests that an increase in the refractive index and a decrease in the extinction coefficient for PIAD MgF2 films after annealing may be related to the enhanced concentration of MgO in the annealed PIAD MgF2 films and the changes in the chemical bonding states of Mg 2p, F 1s, and O is. It is found that (TiO2/MgF2) multilayer filters, consisting of PIAD TiO2 and CE MgF2 films, are as deposited without microcracks and are also thermally stable after annealing.     

Low-temperature preparation and microwave photocatalytic activity study of TiO2-mounted activated carbon

TiO2 thin films were deposited on granular activated carbon by a dip-coating method at low temperature (373 K), using microwave radiation to enhance the crystallization of titania nanoparticles. Uniform and continuous anatase titania films were deposited on the surface of activated carbon. BET surface area of TiO2-mounted activated carbon (TiO2/AC) decreased a little in comparison with activated carbon. TiO2/AC possessed strong optical absorption capacity with a band gap absorption edge around 360 nm. The photocatalytic activity did not increase when the as-synthesized TiO2/AC was thermally treated, but was much higher than commercial P-25 in degradation of phenol by irradiation of electrodeless discharge lamps (EDLs).     

Ti和TiO2薄膜在血管支架表面附着状况的研究

采用非平衡磁控溅射法在316L不锈钢制成的血管支架表面制备Ti以及TiO2薄膜,初步研究了Ti薄膜厚度、TiO2薄膜沉积速率对薄膜在血管支架表面附着状况的影响.结果表明,支架表面较薄的Ti薄膜附着状况较厚的Ti薄膜好;低沉积速率制备的TiO2薄膜在支架表面附着状况好于高沉积速率制备的TiO2薄膜;对于Ti/TiO2复合薄膜,Ti层厚度过大不利于Ti/TiO2复合薄膜在支架表面附着.     

Indium doped ZnO films prepared by RF magnetron sputtering: effect of substrate temperature on the strain-induced band gap

Indium doped zinc oxide (InZnO) thin films were deposited onto corning glass substrates by RF magnetron sputtering. The dependence of crystal structure, surface morphology, optical properties and electrical conductivity on substrate temperature was investigated using XRD, AFM, UV-vis Spectrophotometer, Fluorescence Spectrophotometer and four-point probe. The films were prepared at different substrate temperatures viz, room temperature (RT), 473 K and 673 K at RF power 200 W. All the films showed preferred orientation along (002) direction. Crystallite size increased from 14 to 19 nm as the substrate temperature was increased to 473 K. With increase in substrate temperature the crystallites did not show any further growth. AFM analysis showed that the rms roughness value decreased from 60 nm to 23 nm when the substrate temperature was increased to 673 K. Optical measurements revealed maximum band gap and minimum refractive index for the film prepared at 473 K. A strong correlation between the band gap variation and the strain developed at different substrate temperatures is established.     

N型Bi2Te2.5Se0.5热电薄膜的电阻率与膜厚和温度的关系

在玻璃衬底上通过瞬间蒸发法沉积了厚度为50-400nm的N型Bi2.5Se0.5热电薄膜,沉积温度为473K.采用XRD、EDXA和FESEM技术分别对薄膜的相结构、组成和表面形貌进行了分析研究,在300-350K的温度范围内,研究了薄膜的电阻率与膜厚和温度的相互关系.     

Photocatalytic Property of TiO2 Films Deposited by Pulsed DC Magnetron Sputtering

TiO2 thin films were prepared by DC magnetron sputtering with the oxygen flow rate higher than the threshold. The film deposited for 5 h was of anatase phase with a preferred orientation along the <220> direction, but the films deposited for 2 and 3 h were amorphous. The transmittance and photocatalytic activity of the TiO2 films increased constantly with increasing film thickness. When the annealing temperature was lower than 700℃, only anatase grew in the TiO2 film. TiO2 phase changed from anatase to rutile when the annealing temperature was above 800℃. The photocatalytic activity decreased with increasing annealing temperature.     

The effect of the deposition method on the optical properties of SiO2 thin films

Three films of SiO₂ deposited by three different methods (chemical vapor deposition, electron beam evaporation and r.f. sputtering) were studied to show the effect of the method of preparation on the optical constants of the films. Of the three studied films, the film prepared by electron beam gun deposition showed refractive index values (n) close to the bulk material in the spectral range 300–850 nm. No values for the absorption constant (k) were determined except for the film prepared by r.f. sputtering, which showed higher k values due to the non-stoichiometric structure of the film.     

Titanium monoxide ultra-thin coatings evaporated onto polycrystalline copper films

We evaporated polycrystalline copper thin films of thickness between 10 and 100 nm on silicon substrates with their native oxide under ultra-high-vacuum conditions. Some of them were exposed to air for a period ranging from 1 day to 2 weeks. X-ray photoelectron spectroscopy (XPS) revealed a clean copper surface with a trace of oxygen. These films that were exposed to air presented oxides in the state Cu(II), the amount of CuO depended on the time that the film was exposed to air. Subsequently, we deposited TiO ultra-thin films on polycrystalline copper substrates. Both these thin films were formed by electron beam evaporation. XPS spectra showed that the surface of the titanium monoxide (TiO) films was contamination-free. An evaporation of 0.3 nm of TiO reduced the native oxide of the copper substrates from Cu(II) to Cu(I) or Cu(0) and transformed the TiO into TiO₂ at the interface. Low-energy ion spectroscopy showed that the complete coverage of the substrates depends on the thickness of the copper films. For 10 nm copper thin films the complete coverage occurred at 1.5 nm of TiO, and for 100 nm it occurred at 2.0 nm of TiO. In samples exposed to air, the complete coverage occurred at a film thickness slightly higher than those treated under ultra-high-vacuum conditions.     

Temperature studies of optical parameters of (Ag3AsS3)0.6(As2S3)0.4 thin films prepared by rapid thermal evaporation and pulse laser deposition

(Ag₃AsS₃)_0.6(As₂S₃)_0.4 thin films were deposited using rapid thermal evaporation (RTE) and pulse laser deposition (PLD) techniques. Ag-enriched micrometre-sized cones (RTE) and bubbles (PLD) were observed on the thin film surface. Optical transmission spectra of the thin films were studied in the temperature range 77–300 K. The Urbach behaviour of the optical absorption edge in the thin films due to strong electron–phonon interaction was observed, the main parameters of the Urbach absorption edge were determined. Temperature dependences of the energy position of the exponential absorption edge and the Urbach energy are well described in the Einstein model. Dispersion and temperature dependences of refractive indices were analysed; a non-linear increase of the refractive indices with temperature was revealed. Disordering processes in the thin films were studied and compared with bulk composites, the differences between the thin films prepared by RTE and PLD were analysed.     

Properties of cu-doped low resistive ZnSe films deposited by two-sourced evaporation

Two-sourced evaporation technique is used to prepare hard ZnSe films by controlling the evaporation rates of both Zn and Se at substrate temperature of 400 °C. The films are doped with Cu by immersion in the Cu(NO₃)₂-H₂O solution for different periods of time. The XRD has not shown a drastic change in the film structure while the electrical resistivity of the deposited film dropped from 10⁹ Ω-cm to about 1.6 Ω-cm for solution immersed films after heat treatment. Optical properties of deposited and doped films, such as film thickness, absorption coefficient and optical band gap have been calculated from the normal transmission spectra in the range of 300-2200 nm.The optical results show a decrease of the transmission and an increase of the refractive index and a slight shift in the optical band gap. Chemical composition of the Cu is determined by using absorption of immersed films. The composition of Cu is also compared with the composition detected by electron microprobe analyzer (EMPA).     

平整二钛酸钾薄膜的制备及其气相光催化活性

采用溶胶-凝胶法制备了K2Ti2O5薄膜并进行表征;在K2Ti2O5薄膜表面上形成致密的十八烷基三氯硅烷(C18H37SiCl3,OTS)单层自组装膜(SAMs);用OTS SAMs 水接触角变化研究薄膜的气相光催化活性;测量了薄膜的光电流响应.研究发现:K2Ti2O5薄膜表面平整、均匀、致密、在玻璃基片上透明;在紫外和可见光区都有光吸收;K2Ti2O5薄膜上OTS SAMs在空气中用254nm的紫外光照射时降解速度比在TiO2薄膜上快;K2Ti2O5薄膜产生阳极光电流,比TiO2薄膜具有更强的光激发和更稳定的光电流响应.结果表明,K2Ti2O5薄膜在空气中用紫外光照射能很有效的分解OTS SAMs,是一种很好的治理气相有机污染物的光催化剂.     

A study of the infrared absorption spectra of thin amorphous films of molybdenum trioxide

The spectra of thin amorphous films of MoO₃ deposited by vacuum evaporation have been studied within the spectral range 4000–400 cm^–1 by the Fourier transform infrared technique. Some samples in the thickness range 100 to 400 nm were investigated at room temperature. Four samples were investigated in the substrate deposition temperature range 293 to 543 K. Some samples were annealed in vacuum in the temperature range 473 to 673 K and their IR spectra were recorded as soon as the samples were cooled to room temperature. It has been observed that annealing of the samples at 473 K or above and also heating the substrates in the temperature range 473 K or above, results in the formation of molybdenum species of lower oxidation state than the normal Mo(VI), i.e. Mo(V). This new oxidation state is formed by electron transfer from the oxygen 2p to the molybdenum 4d level.     

Caractères spécifiques des empilements de couches minces métalliques déposées sur des supports à 10 K et à 293 K

In this paper we show that different results are obtained when a silver film of given thickness is deposited in a single evaporation and when it is deposited by the stacking of successive layers. With stacking, the formation of continuous film is delayed. Specific properties are observed for layers evaporated onto substrates at 10 K. In the absence of free electron absorption (very thin films) our results for these films, when analysed according to the theory of David, seem to indicate that the grains grow by maintaining their ellipsoidal shape and the corresponding ratio of the axes. These grains begin to flatten only under Drude absorption. This effect does not seem to occur for the evaporation of successive layers on substrates which are not cooled; here, the grain shape seems to change in a continuous manner.     

Site-specific and patterned growth of TiO(2) nanotube arrays from e-beam evaporated thin titanium film on Si wafer

Growth of TiO(2) nanotubes on thin Ti film deposited on Si wafers with site-specific and patterned growth using a photolithography technique is demonstrated for the first time. Ti films were deposited via e-beam evaporation to a thickness of 350-1000?nm. The use of a fluorinated organic electrolyte at room temperature produced the growth of nanotubes with varying applied voltages of 10-60?V (DC) which remained stable after annealing at 500?°C. It was found that variation of the thickness of the deposited Ti film could be used to control the length of the nanotubes regardless of longer anodization time/voltage. Growth of the nanotubes on a SiO(2) barrier layer over a Si wafer, along with site-specific and patterned growth, enables potential application of TiO(2) nanotubes in NEMS/MEMS-type devices.     

离子源偏压对PIA-EB-Hf法制备的HfO2激光薄膜性能的影响

探究HfO₂薄膜的激光损伤特性以进一步提高激光损伤阈值(Laser Induced Damage Threshold, 简称LIDT), 对其在高功率激光系统中的广泛应用具有重要的意义。在不同的离子源偏压下, 采用等离子体辅助电子束蒸发金属铪(Hf)并充氧(O₂)进行反应沉积法制备了中心波长为1064 nm, 光学厚度为4H的HfO₂薄膜样品。测试了薄膜组分和残余应力; 根据透射谱拟合了薄膜的折射率; 通过XRD谱图和SEM表面形貌图分析了薄膜的微观结构; 对激光损伤阈值、损伤特性和机理进行了论述。结果表明: 偏压100 V时制备的薄膜具有最佳O/Hf配比; 薄膜压应力和折射率均随偏压降低而减小。薄膜内存在结晶, 激光能量在晶界缺陷处被强烈聚集和吸收, 加速了膜层的破坏, 形成由几百纳米的烧灼坑聚集而成的海绵状损伤结构。随着偏压降低, 膜结晶取向由(\stackrel{\text{?}}{1}11)晶面向(002)晶面转变, 界面能降低; 晶粒减小, 结构更均匀, 缓解了激光能量在晶界处的局部聚集与吸收, 表现出较大的激光损伤阈值。     

Structural,optical, and electrical properties of flash-evaporated copper indium diselenide thin films

Copper indium diselenide (CuInSe₂) compound was synthesized by reacting its elemental components, i.e., copper, indium, and selenium, in stoichiometric proportions (i.e., 1:1:2 with 5% excess selenium) in an evacuated quartz ampoule. Structural and compositional characterization of synthesized pulverized material confirms the polycrystalline nature of tetragonal phase and stoichiometry. CuInSe₂ thin films were deposited on soda lime glass substrates kept at different temperatures (300–573 K) using flash evaporation technique. The effect of substrate temperature on structural, morphological, optical, and electrical properties of CuInSe₂ thin films were investigated using X-ray diffraction analysis (XRD), atomic force microscopy (AFM), optical measurements (transmission and reflection), and Hall effect characterization techniques. XRD analysis revealed that CuInSe₂ thin films deposited above 473 K exhibit (112) preferred orientation of grains. Transmission and reflectance measurements analysis suggests that CuInSe₂ thin films deposited at different substrate temperatures have high absorption coefficient (~10⁴ cm⁻¹) and optical energy band gap in the range 0.93–1.02 eV. Results of electrical characterization showed that CuInSe₂ thin films deposited at different substrate temperatures have p-type conductivity and hole mobility value in the range 19–136 cm²/Vs. Variation of energy band gap and resistivity of CuInSe₂ thin films deposited at 523 K with thickness was also studied. The temperature dependence of electrical conductivity measurements showed that CuInSe₂ film deposited at 523 K has an activation energy of ~30 meV.     

Ion-assisted deposition of oxide materials at room temperature by use of different ion sources

Thin films of SiO(2), TiO(2), Ta(2)O(5), ZrO(2), and the mixed oxide H4 (Merck) have been deposited onto nonheated glass substrates by electron-beam evaporation in commercial coating plants. All depositions have been carried out with ion assistance provided by three different ion or plasma sources (end-hall, plasma, and cold-cathode sources). The optical film properties such as index of refraction, extinction coefficient, light scattering, and absorption have been examined by spectrophotometry, laser calorimetry, and total integrated light-scatter measurements. Surface morphology has been investigated by atomic force microscopy studies. Furthermore, films have undergone sand erosion tests for the determination of relative wear resistance. The film properties are compared for the three different ion sources.