All spray pyrolysis deposited CdS sensitized ZnO films for quantum dot-sensitized solar cells

Sensitized-type solar cells based on ZnO photoanode and CdS quantum dots (QDs) as sensitizers have been fabricated. Both ZnO films and CdS QDs are prepared using ultrasonic spray pyrolysis (USP) deposition technique. This method allows a facile and rapid deposition and integration between CdS QDs and ZnO films without the need for post thermal treatment. The photovoltaic performances of the cells are investigated. The results show that the performance of the cell based on all USP deposited CdS sensitized ZnO photoanode achieves maximally a short circuit current density of 6.99 mA cm⁻² and a power conversion efficiency of 1.54%.     

Synthesis and structural characterization of undoped and Co doped zinc oxide thin films obtained by aerosol assisted chemical vapour deposition

Dilute magnetic oxides are transparent, wide-bandgap materials that behave ferromagnetically when doped with a few percent of a magnetic 3d cation. They have attracted a great deal of interest due to the integration of semiconducting and magnetic properties in a material, that is a prerequisite for successful fabrication of useful devices for the emerging technologies of spintronics. Here we report a study of growth characteristics and microstructural properties of undoped and Co doped ZnO films grown onto borosilicate glass substrates, using aerosol assisted chemical vapour deposition method. The obtained films are single phase, of Wurtzite type, some of them with a strong c-axis orientation, i.e. with the c-axis normal to the substrate surface.     

Effects of annealing on elemental composition and quality of CZTSSe thin films obtained by spray pyrolysis

The spray pyrolysis was used for the deposition of Cu₂ZnSn(S, Se)₄ (CZTSSe) kesterite thin films. The basic spray pyrolysis solution was prepared from two precursor solutions containing thiourea and cooled to a temperature near 1°C, which leads to minimizing the number of insoluble hydrates of copper chloride. The optimal substrate temperature was 350°C and the distance from the sprayer nozzle 30 cm. The as-deposited Cu₂ZnSnS₄ layers were annealed in S₂ atmosphere for the compensation of the sulfur deficiency and with the addition of Sn in order to avoid tin loss. Cu₂ZnSn(S, Se)₄ thin films were obtained after the annealing of as-deposited films in the (S₂ + Se₂) atmosphere. The surface morphology and composition of obtained thin films were investigated using the energy dispersive X-ray (EDX) microanalysis and Raman spectroscopy measurements. The structural characterization by the grazing incidence X-ray diffraction (GIXRD) showed the presence of Cu_2–x S phases in all of the annealed thin films. For the Se/(S + Se) ratio of the thin films annealed in the (S + Se) atmosphere was established from EDX measurements and analysis of GIXRD data, the results are in satisfactory agreement.     

Comparison of ZnS thin films fabricated by electrodeposition and spray pyrolysis methods

In this study, ZnS thin films were fabricated using an electrodeposition method from an aqueous electrolytic bath on a molybdenum (Mo) substrate and a spray pyrolysis method on a glass substrate. The potential range in which alloy electrodeposition of Zn and S could be carried out in a solution containing ZnSO₄, Na₂S₂O₃ and Na₃C₆H₅O₇ was determined by cyclic voltammetry. It was revealed that the thin film fabricated by the electrodeposition method was of ZnS and ZnO compounds and its microstructure was porous. The thin film prepared by the spray pyrolysis was smooth, with nano-grains. The band gap of the thin film fabricated by the spray pyrolysis was 3.72 eV, which was higher than that for the thin film fabricated by electrodeposition: 3.64 eV. Finally, the thin film fabricated by the spray pyrolysis was pure ZnS with a hexagonal structure, whereas that by electrodeposition was of ZnS (with a cubic structure) and ZnO compounds.     

An investigation on linear optical properties of dilute Cr doped ZnO thin films synthesized via sol-gel process

Cr doped ZnO thin films were prepared via sol-gel method. The effects of dopant concentration (0%, 1.5% and 3%) annealing temperature and film thickness on UV-Vis spectra of prepared films were investigated. Also, the thickness and surface topology of thin films were investigated by thickness profile meter (DEKTAK) and Atomic Force Microscopy (AFM), respectively. In addition, the band gap and Urbach energy of prepared films were calculated completely for the samples. The results showed that by increasing the dopant concentrations, the microstrain of the prepared thin film structures also increases while the band-gap values decrease. Meanwhile, an increase in annealing temperature makes a decrease in band gap and microstrain of thin films. The increase in thickness resulted in red shift in band gap and reduction in interior microstrains.     

Morphology and optical properties of Co doped ZnO textured thin films

Depending on the ZnO seed-layers, a new kind of cobalt doped zinc oxide (Zn_1−xCo_xO) thin films with controllable morphology were prepared by a facile solvothermal method. A series of ZnO thin films with different Co contents were applied to study the effect of doped Co on morphology, structural and optical properties. It is found that the doped content plays an important role on morphology evolution of Zn_1−xCo_xO films. The results of scanning electron microscope (SEM) indicate that the Zn_1−xCo_xO films are highly uniform and porous. Co has been successfully doped into the ZnO lattice structure and revealed by X-ray diffraction (XRD) and energy dispersive spectrum (EDS). It can be found that Zn_1−xCo_xO thin films possess good crystalline quality through the characterization of transmission electron microscope (TEM) and high-resolution transmission electron microscopy (HRTEM). All of the samples show a stronger violet emission and ultraviolet absorption, and the violet emission peaks shift towards red with increasing of Co content. In addition, the magnetic result demonstrates that the prepared Co-doped ZnO thin films are room-temperature ferromagnetic materials.     

Cu掺杂的ZnO纳米棒阵列膜的结构与阻变性能

以Cu掺杂的ZnO(Cu：ZnO,CZO)薄膜(Thin film,TF)为缓冲层、以水热法制备了CZO纳米棒阵列膜(Nanorods film,NRF),研究了CZO NRF的结构与阻变特性。少量Cu₂₊添加可促进纳米棒的结晶及沿c轴取向生长,补偿本征缺陷。所制备的CZO NRF/CZO TF双层器件具有双极性阻变特性,限制电流对其I-V特性和保持特性影响较大,限制电流较小时,器件的开关比会降低。当I_CC分别为10mA和1mA时,开关比的平均值分别为7460和45。与CZO TF单层器件相比,SET电压分布和高低阻值的稳定性均获得明显改善,V_SET分布在+0.3～1.55V之间,HRS≈7.05×10₅～2.1×10₆Ω,LRS≈134Ω。CZO纳米棒为导电细丝的形成提供了大量氧空位,使导电细丝排列整齐、尺寸更均匀,降低了导电细丝形成的随机性。     

Surface morphology and photoluminescence properties of ZnO thin films obtained by PLD

ZnO thin films on Si(111) substrate were deposited by laser ablation of Zn target in oxygen reactive atmosphere, Nd-YAG laser with wavelength of 1 064 nm was used as laser source. XRD and FESEM microscopy were applied to characterize the structure and surface morphology of the deposited ZnO films. The optical properties of the ZnO thin films were characterized by photoluminescence. The UV and deep level (yellow-green) light were observed from the films. The UV light is the intrinsic property and deep level light is attributed to the existence of antisite defects (Ozn). The intensity of UV and deep level light depends strongly on the surface morphology and is explained by the surface roughness of ZnO film. A strongly UV emission can be obtained from ZnO film with surface roughness in nanometer range.     

Elaboration and characterization of Al doped ZnO nanorod thin films annealed in hydrogen

ZnO thin films doped with Al concentrations of 1.0, 2.0, 3.0, 4.0, 5.0 at% were prepared by a sol-gel spin-coating method on glass substrates and respectively annealed at 550 °C for 2 h in hydrogen and air. The X-ray diffraction and selected-area electron diffraction results confirm that the Al doped ZnO thin films are of wurtzite hexagonal ZnO. The scanning electron microscope results indicate that the Al doped ZnO nanorod thin films can be got by annealing in hydrogen rather than in air. The optical properties reveal that the Al doped ZnO thin films have obviously enhanced transmittance in the visible region. The electrical properties show that the resistivity of 1.0 at% Al doped ZnO thin films has been remarkably reduced from 0.73 Ω m by annealing in air to 3.2 × 10⁻⁵ Ω m by annealing in hydrogen. It is originated that the Al doped ZnO nanorod thin films annealed in hydrogen increased in electron concentration and mobility due to the elimination of adsorbed oxygen species, and multicoordinated hydrogen.     

Properties of Ni doped and Ni-Ga co-doped ZnO thin films prepared by pulsed laser deposition

ZnNiO and Zn(Ni,Ga)O thin films were prepared on glass substrates by pulsed laser deposition. The obtained films are of good crystal quality and have smooth surfaces, which have a hexagonal wurtzite ZnO structure with a highly c-axis orientation without any Ga or Ni related phases. Hall-effect measurements showed that the ZnNiO film is n-type, in which the carrier concentration would be greatly enhanced by the addition of Ga. Room temperature ferromagnetism is observed for the ZnNiO and Zn(Ni,Ga)O films. The addition of Ga into the ZnNiO films increases the electron concentration but weakens the room temperature ferromagnetism.     

The wide band gap of highly oriented nanocrystalline Al doped ZnO thin films from sol–gel dip coating

Undoped and Al doped ZnO thin films were prepared on glass substrate by sol–gel dip coating from PVP-modified zinc acetate dihydrate and aluminium chloride hexahydrate solutions. The XRD patterns of all thin films indexed a highly preferential orientation along c-axis. The AFM images showed the average grain size of undoped ZnO thin film was about 101 nm whereas the smallest average grain size at 8 mol% Al was about 49 nm. The values of direct optical band gap of thin films varied in the range of 3.70–3.87 eV.     

AES and XPS analyses of CuIn(s1-xsex)2thin films grown by spray pyrolysis technique

Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS) analyses of CuIn(S_1−xSe_x)₂ thin films (x = 0.0, 0.5, 0.7 and 1.0) deposited by spray pyrolysis technique have been carried out. AES spectra of as-deposited films showed carbon, chlorine and oxygen as surface contaminants. Sputter etched spectra showed no trace of carbon and chlorine, but about 1.2% oxygen was found to be present. XPS analysis of CuIn(S_1−xSe_x)₂ thin films prepared under optimized conditions revealed the absence of binary secondary phases. However, Cu₂S or CuS was found to be secondary phase in CuIn(S_0.5Se_0.5)₂ thin films.     

Oxygen-free precursor for chemical vapor deposition of gold films: thermal properties and decomposition mechanism

Thermal properties of oxygen-, phosphorus-, and halogen-free dimethylgold(III) diethyldithiocarbamate complex (CH₃)₂AuS₂CN(C₂H₅)₂ (gold, dimethyl(diethylcarbamodithioato -S,S′)-) having excellent storage stability and the mechanism of its decomposition to elemental gold were studied. Saturated vapor pressure was found to be ~10⁻³–10⁻¹ Torr at 50–90°C. Decomposition of the vapor on the surface starts at T = 210°C. The temperature dependence of gas phase composition was studied using the original mass spectrometric technique, it was established that the decomposition of the compound on the surface in vacuum follows three main pathways. Two of them result in the formation of elemental gold, saturated C2–C4 alkanes and (1) protonated ligand or (2) methylated ligand. The third one results in elemental gold and gaseous products: C2–C3 alkylmercaptanes and CH₃SCN(C₂H₅)₂. The formation of gold as a sole solid product within the temperature range 210–240°C was confirmed by X-ray photoelectron spectroscopy analysis. It was shown that the compound exhibits the best combination of volatility, thermal, and storage stability among volatile organogold complexes and thus it may be a promising precursor for obtaining gold films by chemical vapor deposition.     

Structural and optical properties of tellurium films obtained by chemical vapor deposition（CVD）

1 Introduction Te thin films have been extensively used in various technological areas, especially in microelectronic devices such as gas sensor [1?3], optical information storage [4] and other applications [5?7]. All these applications are due to remark…     

Growth and photoluminescence of zinc blende ZnS nanowires via metalorganic chemical vapor deposition

We developed a metalorganic chemical vapor deposition to synthesize ZnS nanowires with high purity on Au-coated sapphire substrates at low temperatures. The ZnS nanowires have zinc blende structure, and most of them have raw-like surface on one edge, while is smooth on the other. High-resolution transmission electron microscopic investigations show that the nanowires are well crystalline single crystal grown along [1 1 1] and are free of bulk defects. The growth mechanism is confirmed as a typical vapor-liquid-solid process. The photoluminescence spectrum reveals two prominent blue emissions centered at 452.2 and 468.6 nm, respectively. It is found that sulfur vacancies and surface states should be responsible for the two blue emissions, respectively.     

Filtered vacuum arc deposition of undoped and doped ZnO thin films: Electrical, optical, and structural properties

Filtered vacuum (cathodic) arc deposition (FVAD, FCVD) of metallic and ceramic thin films at low substrate temperature (50-400 °C) is realized by magnetically directing vacuum arc produced, highly ionized, and energetic plasma beam onto substrates, obtaining high quality coatings at high deposition rates. The plasma beam is magnetically filtered to remove macroparticles that are also produced by the arc. The deposited films are usually characterized by their good optical quality and high adhesion to the substrate. Transparent and electrically conducting (TCO) thin films of ZnO, SnO₂, In₂O₃:Sn (ITO), ZnO:Al (AZO), ZnO:Ga, ZnO:Sb, ZnO:Mg and several types of zinc-stannate oxides (ZnSnO₃, Zn₂SnO₄), which could be used in solar cells, optoelectronic devices, and as gas sensors, have been successfully deposited by FVAD using pure or alloyed zinc cathodes. The oxides are obtained by operating the system with oxygen background at low pressure. Post-deposition treatment has also been applied to improve the properties of TCO films.The deposition rate of FVAD ZnO and ZnO:M thin films, where M is a doping or alloying metal, is in the range of 0.2-15 nm/s. The films are generally nonstoichiometric, polycrystalline n-type semiconductors. In most cases, ZnO films have a wurtzite structure. FVAD of p-type ZnO has also been achieved by Sb doping. The electrical conductivity of as-deposited n-type thin ZnO film is in the range 0.2-6 × 10^− 5 Ω m, carrier electron density is 10²³-2 × 10²⁶ m^− 3, and electron mobility is in the range 10-40 cm²/V s, depending on the deposition parameters: arc current, oxygen pressure, substrate bias, and substrate temperature. As the energy band gap of FVAD ZnO films is ∼ 3.3 eV and its extinction coefficient (k) in the visible and near-IR range is smaller than 0.02, the optical transmission of 500 nm thick ZnO film is ∼ 0.90.     

Impedance and XPS study of benzotriazole films formed on copper, copper-zinc alloys and zinc in chloride solution

The formation of protective layers on copper, zinc and copper-zinc (Cu-10Zn and Cu-40Zn) alloys at open circuit potential in aerated, near neutral 0.5 M NaCl solution containing benzotriazole was studied using electrochemical impedance spectroscopy (EIS) and X-ray photoelectron spectroscopy (XPS). Benzotriazole (BTAH), generally known as an inhibitor of copper corrosion, also proved to be an efficient inhibitor for copper-zinc alloys and zinc metal. The surface layers formed on alloys in BTAH-inhibited solution comprised both polymer and oxide components, namely Cu(I)BTA and Zn(II)BTA polymers and Cu₂O and ZnO oxides, as proved by the in-depth profiling of the layers formed. A tentative structural model describing the improved corrosion resistance of Cu, Cu-xZn alloys and Zn in BTAH containing chloride solution is proposed.     

Sol-gel derived Li-Mg co-doped ZnO films: Preparation and characterization via XRD, XPS, FESEM

Li-Mg co-doped ZnO films have been deposited onto glass substrates by sol-gel spin coating method. The structural and morphological properties of the films were characterized by X-ray diffractometer (XRD), X-ray photo-electron spectroscopy (XPS) and field emission scanning electron microscopy (FESEM). The XRD spectra indicated that the films have polycrystalline nature. The crystallite size values decreased with the increasing Mg content. The chemical composition of the Li-Mg co-doped ZnO films were confirmed by XPS. Additionally, XPS results clearly showed the existence of Mg as a doping element into ZnO crystal lattice. The surface morphology of the films was found to depend on the concentration of Mg in the ZnO:Li. The absorption band edge values of the films were calculated and these values of the films increased with increasing Mg concentration. The refractive index dispersion curves of the films obeyed the single-oscillator model. The dispersion parameters such as E_o (single-oscillator energy) and E_d (dispersive energy) of the films were determined and increase with Mg content.     

氧化锌贫矿提锌渣中铅和银的氯盐一步浸出

运用X射线衍射、扫描电镜和X射线能谱等分析手段,对山东某地深度氧化锌贫矿提锌后渣进行工艺矿物学特征分析可知,矿物中金属赋存状态复杂,属难选矿物。开发出氯盐一步法浸出铅和银的新工艺,考察反应温度、NaCl浓度、添加剂用量、液固比、HCl加入量和浸出时间对浸出过程的影响。结果表明:加入添加剂对铅的浸出率没有影响,但可以显著提高银的浸出率。条件试验研究得出最佳工艺条件如下:浸出温度90℃、NaCl浓度390 g/L、添加剂用量15 mL、液固比(质量比)7?1、HCl加入量3 mL、浸出时间3 h。在此最佳工艺条件下,铅的浸出率达到95%左右,银的浸出率达到90%左右。     

Analysis of electrochemical noise obtained from pure aluminium in neutral chloride and alkaline solutions

The present work involves the analysis of electrochemical noise obtained from pure aluminium during breakdown of the oxide film in aqueous neutral chloride solution and hydrogen evolution in alkaline solution. Since the noise data involve information on such stochastic processes as uniform corrosion, breakdown of the oxide film and hydrogen evolution, they were analysed based upon a stochastic theory: the plot of the cumulative probability numerically calculated was first transformed from the domain of the frequency of events to the mean free time domain and then, the Weibull probability plot was constructed by fitting Weibull distribution function to the calculated cumulative probability. Finally, the conditional event generation rate was numerically determined as a function of time. From two linear regions in one Weibull probability plot, it was concluded that breakdown of the oxide film and hydrogen evolution, respectively, were clearly distinguished from uniform corrosion in the Weibull probability plot. In addition, the roles of anion additives in breakdown of the oxide film and hydrogen evolution were also discussed in terms of the distribution of the mean free time and the conditional event generation rate.