Structural and optical properties of electrodeposited ZnO thin films on conductive RuO2 oxides

ZnO thin films were grown on the 150 nm-thick RuO₂-coated SiO₂/Si substrates by electrochemical deposition in zinc nitrate aqueous solution with various electrolyte concentrations and deposition currents. Crystal orientation and surface structure of the electrodeposited ZnO thin films were characterized by X-ray diffraction (XRD) and scanning electron microscopy, respectively. The XRD results show the as-electrodeposited ZnO thin films on the RuO₂/SiO₂/Si substrates have mixed crystallographic orientations. The higher electrolyte concentration results in the ZnO thin films with a higher degree of c-axis orientation. Moreover, the use of an ultra-thin 5 nm-thick ZnO buffer layer on the RuO₂/SiO₂/Si substrate markedly improves the degree of preferential c-axis orientation of the electrodeposited ZnO crystalline. The subsequent annealing in vacuum at a low temperature of 300 °C reduces the possible hydrate species in the electrodeposited films. The electrodeposited ZnO thin films on the 5 nm-thick ZnO buffered RuO₂/SiO₂/Si substrates grown in 0.02 M electrolyte at −1.5 mA with a subsequent annealing in vacuum at 300 °C had the best structural and optical properties. The UV to visible emission intensity ratio of the film can reach 7.62.     

Structural, optical and electrical properties of CuIn5S8 thin films grown by thermal evaporation method

Stoichiometric compound of copper indium sulfur (CuIn₅S₈) was synthesized by direct reaction of high purity elemental copper, indium and sulfur in an evacuated quartz tube. The phase structure of the synthesized material revealed the cubic spinel structure. The lattice parameter (a) of single crystals was calculated to be 10.667 Å. Thin films of CuIn₅S₈ were deposited onto glass substrates under the pressure of 10⁻⁶ Torr using thermal evaporation technique. CuIn₅S₈ thin films were then thermally annealed in air from 100 to 300 °C for 2 h. The effects of thermal annealing on their physico-chemical properties were investigated using X-ray diffraction (XRD), Energy-dispersive X-ray spectroscopy (EDX), scanning electron microscope (SEM), optical transmission and hot probe method. XRD studies of CuIn₅S₈ thin films showed that as-deposited films were amorphous in nature and transformed into polycrystalline spinel structure with strong preferred orientation along the (3 1 1) plane after the annealing at 200 °C. The composition is greatly affected by thermal treatment. From the optical transmission and reflection, an important absorption coefficient exceeds 10⁴ cm⁻¹ was found. As increasing the annealing temperature, the optical energy band gap decreases from 1.83 eV for the as-deposited films to 1.43 eV for the annealed films at 300 °C. It was found that CuIn₅S₈ thin film is an n-type semiconductor at 300 °C.     

Characterization of cobalt oxide thin films prepared by a facile spray pyrolysis technique using perfume atomizer

Cobalt oxide (Co₃O₄) thin films were prepared by a facile spray pyrolysis technique using perfume atomizer from aqueous solution of hydrated cobalt chloride salt (CoCl₂·6H₂O) as source of cobalt. The films were deposited onto the amorphous glass substrates kept at different temperatures (300-500 °C). The influences of molar concentration of the starting solution and substrate temperature on the structural, morphological and optical properties of (Co₃O₄) thin films were studied. It was found from X-ray diffraction (XRD) analysis that the films prepared with molar concentration greater than 0.025 M/L were polycrystalline spinel type cubic structure. The preferred orientation of the crystallites of these films changes gradually from (6 2 2) to (1 1 1) when the substrate temperature increases. By Raman spectroscopy, five Raman active modes characteristic of Co₃O₄ spinel type cubic structure were found and identified at 194, 484, 522, 620 and 691 cm⁻¹. The scanning electron microscopy (SEM) images showed micro porous structure with very fine grains less than 50 nm in diameter. These films exhibited also a transmittance value of about 70% in the visible and infra red range.     

Low temperature growth of nanocrystalline TiO2 films with Ar/O2 low-field helicon plasma

TiO₂ thin films were deposited on silicon wafer substrates by low-field (1 < B < 5 mT) helicon plasma assisted reactive sputtering in a mixture of pure argon and oxygen. The influence of the positive ion density on the substrate and the post-annealing treatment on the films density, refractive index, chemical composition and crystalline structure was analysed by reflectometry, Rutherford backscattering spectroscopy (RBS) and X-ray diffraction (XRD). Amorphous TiO₂ was obtained for ion density on the substrate below 7 × 10¹⁶ m^− 3. Increasing the ion density over 7 × 10¹⁶ m^− 3 led to the formation of nanocrystalline (~ 15 nm) rutile phase TiO₂. The post-annealing treatment of the films in air at 300 °C induced the complete crystallisation of the amorphous films to nanocrystals of anatase (~ 40 nm) while the rutile films shows no significant change meaning that they were already fully crystallised by the plasma process. All these results show an efficient process by low-field helicon plasma sputtering process to fabricate stoichiometric TiO₂ thin films with amorphous or nanocrystalline rutile structure directly from low temperature plasma processing conditions and nanocrystalline anatase structure with a moderate annealing treatment.     

Microwave assisted chemical bath deposited polyaniline films for supercapacitor application

In the present investigation, we are reporting the first time synthesis of polyaniline (PANI) thin films by microwave assisted chemical bath deposition (MW-CBD) method on the stainless steel substrate. The PANI thin films are prepared by the oxidation of aniline in the domestic microwave oven working with frequency 2.45 GHz. The PANI thin films are characterized for their structural, morphological and optical studies by means of X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM) and UV-vis spectrophotometer. The wettability study is carried out by measuring the contact angle. The supercapacitive behavior of PANI electrode is studied in 0.5 M H₂SO₄ using cyclic voltammetric (CV) measurements. The X-ray diffraction pattern showed the films are amorphous. Morphological study revealed PANI thin film is well covered over the entire substrate surface with less overgrown fine spherical granules. The optical band gap of PANI thin film is found to be 2.5 eV. The hydrophilic nature of the PANI thin films is observed from water contact angle measurement. A maximum specific capacitance is found to be 753 F g⁻¹ at the scan rate of 5 mV s⁻¹.     

Synthesis of layered birnessite-type manganese oxide thin films on plastic substrates by chemical bath deposition for flexible transparent supercapacitors

Layered birnessite-type manganese oxide thin films are successfully fabricated on indium tin oxide coated polyethylene terephthalate substrates for flexible transparent supercapacitors by a facile, effective and inexpensive chemical bath deposition technology from an alkaline KMnO₄ aqueous solution at room temperature. The effects of deposition conditions, including KMnO₄ concentration, initial molar ratio of NH₃·H₂O and KMnO₄, bath temperature, and reaction time, on the electrochemical properties of MnO₂ thin films are investigated. Layered birnessite-type MnO₂ thin films deposited under optimum conditions display three-dimensional porous morphology, high hydrophilicity, and a transmittance of 77.4% at 550 nm. A special capacitance of 229.2 F g⁻¹ and a capacitance retention ratio of 83% are obtained from the films after 1000 cycles at 10 mV s⁻¹ in 1 M Na₂SO₄. Compressive and tensile bending tests show that as-prepared MnO₂ thin film electrodes possess excellent mechanical flexibility and electrochemical stability.     

Room-temperature synthesis of crystallized LiCoO2 thin films by electrochemical technique

LiCoO₂ thin films have been directly synthesized on cobalt substrate in LiOH solution at room temperature by electrochemical method. The obtained LiCoO₂ thin films were characterized by X-ray diffraction (XRD), scanning electronic microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The influence of electrochemical reaction time, current density and concentration of LiOH solution on the crystal structure and morphology of the obtained LiCoO₂ thin films was discussed emphatically. Our results show that the as-synthesized LiCoO₂ films all are pure hexagonal structure. The crystallinity, densification and uniformity of the films increase with increasing electrochemical reaction time, current density as well as concentration of LiOH solution and then decrease. The preferable electrochemical reaction conditions were optimized as: electrochemical reaction time is 50 h, current density is 1 mA cm⁻² and concentration of LiOH solution is 3 mol dm⁻³.     

Structural, optical and electrical properties of N-doped ZnO thin films prepared by thermal oxidation of pulsed filtered cathodic vacuum arc deposited ZnxNy films

In this study, N-doped ZnO thin films were fabricated by oxidation of Zn_xN_y films. The Zn_xN_y thin films were deposited on glass substrates by pulsed filtered cathodic vacuum arc deposition (PFCVAD) using metallic zinc wire (99.999%) as a cathode target in pure nitrogen plasma. The influence of oxidation temperature, on the electrical, structural and optical properties of N-doped ZnO films was investigated. P-type conduction was achieved for the N-doped ZnO obtained at 450 °C by oxidation of Zn_xN_y, with a resistivity of 16.1 Ω cm, hole concentration of 2.03 × 10¹⁶ cm⁻³ and Hall mobility of 19 cm²/V s. X-ray photoelectron spectroscopy (XPS) analysis confirmed the incorporation of N into the ZnO films. X-ray diffraction (XRD) pattern showed that the films as-deposited and oxidized at 350 °C were amorphous. However, the oxidized films in air atmosphere at 450-550 °C were polycrystalline without preferential orientation. In room temperature photoluminescence (PL) spectra, an ultraviolet (UV) peak was seen for all the samples. In addition, a broad deep level emission was observed.     

Octylphenol ethoxylate surfactant as a suppressor in copper electrodeposition

In this study, the role of octylphenol ethoxylate (Triton X-100) surfactant as a suppressor in Cu electrodeposition has been examined. The inhibition ability of Triton X-100 was qualitatively and quantitatively evaluated with cyclic voltammograms and Koutecký–Levich plots, and compared with that of polyethylene glycol (PEG) with similar molecular size. The presence of a hydrophobic benzene-ring in its structure made it inhibit Cu deposition more strongly than PEG. The inhibition function of Triton X-100 depended on the substrate material and it was influenced by the presence of Cl^? and bis sulphopropyl disulphide in the electrolyte indicating that the characteristics of Triton X-100 were similar to those of PEG, which was also demonstrated by gap filling of Cu with using Triton X-100 in the replacement of PEG. The effect of Triton X-100 on the properties of the deposit film was also investigated, and it was found that it suppressed the three-dimensional growth of Cu.     

Chemically synthesized hydrous RuO2 thin films for supercapacitor application

The hydrous RuO₂ thin films have been successfully synthesized at low temperature on glass and stainless steel substrates using lucrative chemical bath deposition (CBD) method. Their structural, morphological, optical, electrical and wettability properties were studied by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FT-IR), UV-vis-NIR spectrophotometer, two point probe method and water contact angle measurement techniques. The results showed that, the CBD method allows to formation of amorphous, porous, superhydrophilic, semiconducting, hydrous RuO₂ thin films with optical band gap of 2.7 eV. The supercapacitive behavior of hydrous RuO₂ in 0.5 M H₂SO₄ electrolyte examined by cyclic voltammetric (CV) measurements showed maximum specific capacitance of 73 F g⁻¹.     

Synthesis of nanocrystalline nickel-zinc ferrite (Ni0.8Zn0.2Fe2O4) thin films by chemical bath deposition method

The nickel-zinc ferrite (Ni_0.8Zn_0.2Fe₂O₄) thin films have been successfully deposited on stainless steel substrates using a chemical bath deposition method from alkaline bath. The films were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), static water contact angle and cyclic voltammetry measurements. The X-ray diffraction pattern shows that deposited Ni_0.8Zn_0.2Fe₂O₄ thin films were oriented along (3 1 1) plane. The FTIR spectra showed strong absorption peaks around 600 cm⁻¹ which are typical for cubic spinel crystal structure. SEM study revealed compact flakes like morphology having thickness ∼1.8 μm after air annealing. The annealed films were super hydrophilic in nature having a static water contact angle (θ) of 5°.The electrochemical supercapacitor study of Ni_0.8Zn_0.2Fe₂O₄ thin films has been carried out in 6 M KOH electrolyte.The values of interfacial and specific capacitances obtained were 0.0285 F cm⁻² and 19 F g⁻¹, respectively.     

单链DNA/表面活性剂与单壁碳纳米管的亲合力及荧光检测性能(英文)

研制一种基于单链DNA与单壁碳纳米管荧光变化的新型荧光探针用于表面活性剂物质的检测方法。考察了温度对探针稳定性的影响,通过观察实时荧光光谱变化来评估单壁碳纳米管与5种常见表面活性剂物质的亲和性,观察镁离子及pH对探针检测表面活性物质的影响,通过观察荧光发射光谱变化来考察加入不同浓度表面活性物质曲拉通X-100后荧光探针的荧光恢复情况。结果表明,在5~80°C的温度范围内,探针十分稳定;单壁碳纳米管与5种常见表面活性物质的亲和力由强至弱依次为曲拉通X-100、十二烷基苯磺酸钠、吐温-20、吐温-80、十二烷硫酸钠;荧光探针检测的最佳Mg2+浓度为10mmol/L,pH为7.4;当加入不同浓度的表面活性剂物质曲拉通X-100时,探针体系的荧光逐渐得到恢复。     

磁过滤阴极弧法制备CrCN薄膜结构与组分研究

目的通过磁过滤阴极弧沉积技术制备质量优异的CrCN涂层。研究乙炔/氮气混合气体流量以及基底偏压对薄膜结构和成分的影响。方法采用磁过滤真空阴极弧沉积技术,在20~100 m L/min变化的乙炔/氮气混合气体流量参数下沉积CrCN复合薄膜。通过X射线衍射、场发射电子显微镜、扫描探针显微镜、X射线光电子能谱仪、透射电镜,对薄膜的物相结构和形貌进行分析。结果随着气体流量的增加,CrCN复合薄膜的晶粒逐渐减小最终向非晶化转变。TEM结果表明,在CrCN复合薄膜中有大量几纳米到十几纳米的纳米晶浸没在非晶成分中。SPM表明,随着基底偏压由–200 V增大到–150 V,CrCN薄膜的表面粗糙度Sa由0.345 nm上升至4.38 nm。XPS、TEM和XRD数据表明,薄膜中Cr元素主要以单质Cr、Cr N以及Cr3C2的形式存在。结论采用磁过滤真空阴极弧沉积技术制备的CrCN复合薄膜具有纳米晶-非晶镶嵌结构。该方法沉积的CrCN薄膜的表面粗糙度与基底负偏压有关。混合气体的流量变化对薄膜组分的变化几乎无影响。     

Supercapacitor behavior of CuO-PAA hybrid films: Effect of PAA concentration

The Cu-poly(acrylic) acid (PAA) thin films were deposited at room temperature by a simple and cost effective polymer assisted deposition (PAD) method. The solution containing Cu salt and PAA was spin coated to yield the thin films with desired properties. The Cu-PAA films were annealed at 400 °C in ambient air for 4 h to obtain CuO-PAA phase. The effect of PAA concentration on the film properties is studied and characterized by employing various techniques. The structural and surface morphological studies are carried out using X-ray diffraction (XRD) and scanning electron microscope (SEM) respectively. Fourier transform infrared spectroscopy (FT-IR) and FT-Raman spectroscopy are employed to investigate the hybrid film formation. Wetting behavior is studied by measuring the contact angle of water on the film surface. Cyclic voltammetry (CV) studies were carried out to investigate the specific capacitance of CuO-PAA films in aqueous 1 M H₂SO₄ electrolyte. Hybrid films deposited with 2 mM PAA exhibits highest specific capacitance of 65 F g⁻¹.     

Structural and optical study of samarium doped cerium oxide thin films prepared by electron beam evaporation

Samarium doped cerium oxide films were grown on the glass substrate using e-beam deposition technique and then characterized using different techniques: X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), Raman spectroscopy and UV-visible spectroscopy measurements. XRD analysis shows that all the films have cubic structure and the crystallite size decreases from 18 to 13 nm as the samarium (Sm) concentration increases. The FE-SEM images indicate that all the films have columnar growth. UV-visible measurements reflect that the films have high transparency (>80%) in the visible region. From the Raman spectra, we have observed two peaks at 466 and 565 cm⁻¹. The peak at 466 cm⁻¹ is assigned to the F_2g mode of cerium oxide (CeO₂) whereas the peak at 565 cm⁻¹ is due to the presence of the oxygen vacancies. The increase in the intensity of the peak at 565 cm⁻¹ indicates that the oxygen vacancy increases with Sm doping.     

Influence of heat treatment on the particle size of nanobrookite TiO2 thin films produced by sol-gel method

Pure nanobrookite titania (TiO₂) thin films were deposited on glass substrates by the spin-coating method using titanium butoxide and acetic acid. The particle sizes of TiO₂ films were controlled by heat treatment temperatures. The activation energy for particle growth was calculated as 23.1 kJ/mol. The structural and optical properties of the nanobrookite TiO₂ thin films were characterized by X-ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM), ultraviolet-visible absorption spectroscopy (UV-vis), and Fourier transform infrared spectroscopy (FTIR).     

Effect of hydrogen flow on the properties of hydrogenated amorphous carbon films fabricated by electron cyclotron resonance plasma enhanced chemical vapor deposition

The hydrogenated amorphous carbon films (a-C:H, so-called diamond-like carbon, DLC) have exceptional physical and mechanical properties and have wide applications. In the present study, amorphous hydrogenated carbon films (a-C:H) have been deposited on a Si (100) substrate at different hydrogen flow using electron cyclotron resonance chemical vapor deposition (ECR-CVD). The flow of hydrogen changed from 10 sccm to 40 sccm and the flow of acetylene was fixed at 10 sccm. The microstructure and properties of the a-C:H were measured using visible Raman spectra, Fourier transform infrared (FTIR) spectroscopy, UV-VIS spectrometer,surface profilometer and nano-indentation. The results showed that the sp³ content and sp³-CH₂ structure in the amorphous hydrogenated carbon films increased with the hydrogen flow. The deposition rate decreased with the hydrogen flow. The residual stress and the nano-hardness of the amorphous hydrogenated carbon films increased with the hydrogen flow. Consequently, the a-C:H film become more diamond-like with the increase of hydrogen flow.     

Composition and mechanical properties of AlC, AlN and AlCN thin films obtained by r.f. magnetron sputtering

Aluminum carbide (Al-C), aluminum nitride (Al-N), and aluminum carbonitride (Al-C-N) thin films were grown onto Si [100] substrates by r.f. reactive magnetron sputtering at 400 °C. The Al-N coatings were obtained by sputtering of Al (99.9%) target in Ar/N₂ atmosphere and the Al-C and Al-C-N by co-sputtering of a binary (50% Al, 50% C) target in argon and in Ar/N₂ mixture, respectively. The d.c. bias voltage was varied between 0 and − 150 V. The films were characterized by X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), Fourier transformed infrared spectroscopy (FTIR) and the mechanical properties by nanoindentation. The structure of the films has been determined by XRD, which shows that amorphous films are formed in all cases. The variation of polarization bias voltage produced chemical differences in the films. As the bias voltage is increased, the Al content is reduced in all three materials. The nitrogen content also varied between 10 and 14 at.% for Al-N coatings, remaining practically constant (21 at.%) for the Al-C-N films. The Berkovich hardness results were 7.0, 17.2 and 9.2 GPa for Al-C, Al-N, and Al-C-N films, respectively.     

Electrical and optical properties of tantalum oxide thin films prepared by reactive magnetron sputtering

Tantalum oxide thin films were prepared by using reactive dc magnetron sputtering in the mixed atmosphere of Ar and O₂ with various flow ratios. The structure and O/Ta atom ratio of the thin films were analyzed by X-ray diffraction and X-ray photoelectron spectroscopy (XPS). The optical and dielectric properties of the Ta₂O₅ thin films were investigated by using ultraviolet-visible spectra, spectral ellipsometry and dielectric spectra. The results reveal that the structure of the samples changes from the amorphous phase to the β-Ta₂O₅ phase after annealing at 900 °C. The XPS analysis showed that the atomic ratio of O and Ta atom is a stoichiometric ratio of 2.50 for the sample deposited at Ar:O₂ = 4:1. The refractive index of the thin films is 2.11 within the wavelength range 300-1000 nm. The dielectric constants and loss tangents of the Ta₂O₅ thin films decrease with the increase of measurement frequency. The leakage current density of the Ta₂O₅ thin films decreases and the breakdown strength increases with the increase of Ar:O₂ flow ratios during deposition.     

Formation of barrier-type anodic films on sputtering-deposited Al-Ti alloys

The formation of amorphous anodic films at constant current is investigated for sputtering-deposited Al-Ti alloys containing from 3-30 at.% Ti. The films were grown at high efficiency in a borate electrolyte and comprised a main region containing units of Al₂O₃ and TiO₂, with a thin surface region enriched in titanium species. The formation ratios of the films increased with increase of titanium content of the alloys. The presence of the outer region is explained by the faster migration of Ti⁴⁺ ions relative to that of Al³⁺ ions through the films.