A study of electrodeposition of CuInSe2 thin films with triethanolamine as the complexing agent

In this article, the electrochemistry of CuInSe₂ and its compositional ingredients CuCl₂, InCl₃ and SeO₂ in aqueous solution were investigated. Triethanolamine was added in the single-step electrodeposition of CuInSe₂ from aqueous solution as the complexing agent in order to improve the crystallinity and uniformity of the layer. The stoichiometry, crystal structure and grain sizes of CuInSe₂ thin films of various deposition conditions were compared. The deposition parameters such as the concentration of complexing agent, deposition potential, deposition time and annealing temperature are found to be important factors in the processes of electrical deposition of CuInSe₂ thin films.     

Preparation and characterization of thermally evaporated titanium phthalocyanine dichloride thin films

Titanium phthalocyanine dichloride (TiPcCl₂) thin films are prepared on glass substrates by vacuum-sublimation technique. The optical constants of thin films are obtained by means of thin film spectrophotometry. Planar structures for the study of electrical properties are fabricated with TiPcCl₂ as active layer and silver as the contact electrodes. The effects of post-deposition annealing on the optical band gap have been studied. The optical transition is found to be direct allowed in nature. The invariance in the optical band gap shows the thermal stability of the material. The activation energies are determined using the Arrhenius plots between electrical conductivity and inverse temperature. The variation in activation energy with post-deposition annealing is investigated. The unit cell dimensions of TiPcCl₂ thin films are also determined by indexing the powder diffraction data. The variations of the surface morphology and grain size with annealing have also been studied.     

Studies of single-step electrodeposition of CuInSe2 thin films with sodium citrate as a complexing agent

The influences of various parameters in a single-step electrodeposition of CuInSe₂ from aqueous solution containing CuCl₂, InCl₃, and SeO₂, with sodium citrate as the complexing agent, are investigated. Co-deposition of CuInSe₂ from a room temperature, aqueous bath of these electrolytes is accomplished by the aid of sodium citrate. In this work the optimum potential for deposition of CuInSe₂ is found to be −0.5 V vs. Ag/AgCl, the deposition time is 800 s, the concentration ratio of CuCl₂, InCl₃, and SeO₂ is 9 mM:22 mM:22 mM in aqueous solution, and the annealing temperature is 225 °C. Under the optimum conditions, crystalline layers of CuInSe₂ having the chalcopyrite structure can be successfully synthesized. Cyclic voltammetry (CV), scanning electron microscope (SEM), X-ray diffractometer (XRD), and energy dispersive X-ray spectrometer (EDX) were used to examine the electrochemistry, morphologies, structures, and compositions of CuInSe₂ thin films deposited on ITO glass.     

Preparation of CuInSe2/CuGaSe2 two layers absorber film by metal–organic chemical vapor deposition

Deposition of CuInSe₂ thin film on CuGaSe₂ thin film and vice versa has been studied by a low pressure metal–organic chemical vapor deposition technique with three precursors without additional Se. The properties of the resultant films have been examined by scanning electron microscopy, X-ray diffraction, and micro-Raman scattering. Good quality and well demarcated films are obtained only in the case of CuInSe₂ grown on CuGaSe₂. When CuGaSe₂ was grown on top of CuInSe₂ diffusion of Ga into CuInSe₂ was found to produce an alloy film instead.     

The study of electronic conduction in amorphous thin films of Al-In<Subscript>2</Subscript>O<Subscript>3</Subscript>-Al structure deposited by thermal evaporation

A discussion of electronic conduction in amorphous thin films of Al-In₂O₃-Al structure is presented. Particular attention is given to the question of film thickness, substrate temperature during deposition and post-deposition annealing, since these conditions are known to have a profound effect on the structure and electrical properties of the films. The effects of temperature on the V-I characteristics and effects of frequency on conductivity and capacitance of the Al-In₂O₃-Al structure are also reported. Activation energies for conduction processes are estimated and the results are discussed in terms of the hopping model. The conduction at higher temperature is seemingly a contact-limited, i.e. Schottky type process, so a transition from hopping to free-band conduction takes place. The capacitance decreases with the rise of frequency and the lowering of temperature. The values of dielectric constants are estimated and the results are discussed in terms of Schottky type of conduction. The increase in conductivity with the increase in temperature during measurements of electrical properties, film thickness, substrate temperature and post deposition annealing is reported and results are discussed in terms of current theory.     

Effect of annealing temperature on photoelectrochemical properties of nanocrystalline MoBi2(Se0.5Te0.5)5 thin films

Nanocrystalline MoBi₂(Se_0.5Te_0.5)₅ thermoelectric thin films have been deposited on ultrasonically cleaned glass and FTO-coated glass substrates by Arrested Precipitation Technique. The change in properties of MoBi₂(Se_0.5Te_0.5)₅ thin films were examined after annealing at the temperature 473 K for 3 h. The structural, morphological, compositional and electrical properties of thin films were characterized by X-ray Diffraction, Scanning Electron Microscopy, Energy Dispersive Spectroscopy, etc. Thermoelectric properties of the thin films have been evaluated by measurements of electrical conductivity and Seebeck coefficient in the temperature range 300–500 K. Our aim is to investigate the effect of annealing on behaviour of MoBi₂(Se_0.5Te_0.5)₅ thin films along with photoelectrochemical properties.     

Preparation of transparent conductive TiO2:Nb thin films by pulsed laser deposition

This study investigated the optical and electrical properties of Nb-doped TiO₂ thin films prepared by pulsed laser deposition (PLD). The PLD conditions were optimized to fabricate Nb-doped TiO₂ thin films with an improved electrical conductivity and crystalline structure. XRD analyses revealed that the deposition at room temperature in 0.92 Pa O₂ was suitable to produce anatase-type TiO₂. A Nb-doped TiO₂ thin film attained a resistivity as low as 6.7 × 10⁻⁴ Ω cm after annealing at 350 °C in vacuum (<10⁻⁵ Pa), thereby maintaining the transmittance as high as 60% in the UV-vis region.     

Role of annealing on morphological,linear and nonlinear properties of nanoparticle of Tris [2-phenylpyridinato-C2, N] Iridium III films prepared by electron beam evaporator

Tris(2-phenylpyridinato-C₂, N] Iridium III, Ir(ppy)₃, is experimentally investigated as a novel deposited thin film. Ir(ppy)₃ thin films were fabricated by the electron beam evaporator technique. X-ray diffraction (XRD) of Ir(ppy)₃ powder is investigated to be polycrystalline with triclinic crystal. XRD pattern of Ir(ppy)₃ film and the annealed film is analyzed, and the average of crystallite size slightly increases with thermal annealing from 14 to 40 nm. The linear optical parameters were estimated and found that the annealing effect on lattice dielectric constants, dispersion energy, oscillator energy, and the ratio of carrier concentration to its effective mass. The Urbach energy and optical energy gap are estimated at different thermal annealing. On the other hand, dielectric constants and optical conductivity were estimated and found that the annealing plays a remarkable role in the increasing of their values. The calculated values of third-order susceptibility were increased by thermal annealing. Thus, the thermal annealing can be utilized as a tool to modify the optical properties of Ir(ppy)₃ films, which can be used in many important applications such as high capacity communication network.     

Experimental studies of the thermal properties of thin films by a probe technique with periodic heating

The thermal properties of SrTiO₃ thin films are investigated experimentally by recording the amplitude and phase of the temperature oscillations of a flat probe with the heat flux perpendicular to the plane of the film. Results are given from measurements of the specific heat and thermal conductivity of a leucosapphire substrate and the thermal conductivity of a SrTiO₃ film of thickness 2 μm. Fiz. Tverd. Tela (St. Petersburg) 39, 1299–1302 (July 1997)     

Microstructures and electrical conductivity of nanocrystalline ceria-based thin films

Ceria-based thin films are potential materials for use as gas-sensing layers and electrolytes in micro-solid oxide fuel cells. Since the average grain sizes of these films are on the nanocrystalline scale (< 150 nm), it is of fundamental interest whether the electrical conductivity might differ from microcrystalline ceria-based ceramics. In this study, CeO₂ and Ce_0.8Gd_0.2O_1.9−x thin films have been fabrication by spray pyrolysis and pulsed laser deposition, and the influence of the ambient average grain size on the total DC conductivity is investigated. Dense and crack-free CeO₂ and Ce_0.8Gd_0.2O_1.9−x thin films were produced that withstand annealing up to temperatures of 1100 °C. The dopant concentration and annealing temperature affect highly the grain growth kinetics of ceria-based thin films. Large concentrations of dopant exert Zener drag on grain growth and result in retarded grain growth. An increased total DC conductivity and decreased activation energy was observed when the average grain size of a CeO₂ or Ce_0.8Gd_0.2O_1.9−x thin film was decreased.     

Low-cost 3D nanocomposite solar cells obtained by electrodeposition of CuInSe2

Thin CuInSe₂ films have been prepared by electrodeposition from a single bath aqueous solution on both dense and nanoporous TiO₂. The films are deposited potentiostatically using a N₂-purged electrolyte at different potentials. Various deposition times and solution compositions have been employed. The effect of annealing in air and in argon at different temperatures and times is also investigated. Thin films and nanocomposites of TiO₂ and CuInSe₂ have been studied with electron microscopy, X-ray diffraction, Raman spectroscopy, and optical absorption spectroscopy. After a thermal anneal in argon at 350 °C for 30 min excellent CuInSe₂ is obtained. In particular the nominal crystal structure and the bandgap of 1.0 eV are found. Although pinholes are present occasionally, good samples with diode curves showing a rectification ratio of 24 at ±1 V are obtained. Upon irradiation with simulated solar light of 1000 W m⁻² a clear photoconductivity response is observed. Furthermore, also some photovoltaic energy conversion is found in TiO₂|CuInSe₂ nanocomposites.     

Properties of NiO thin films deposited by chemical spray pyrolysis using different precursor solutions

NiO thin films have been deposited by chemical spray pyrolysis using a perfume atomizer to grow the aerosol. The influence of the precursor, nickel chloride hexahydrate (NiCl₂·6H₂O), nickel nitrate hexahydrate (Ni(NO₃)₂·6H₂O), nickel hydroxide hexahydrate (Ni(OH)₂·6H₂O), nickel sulfate tetrahydrate (NiSO₄·4H₂O), on the thin films properties has been studied. In the experimental conditions used (substrate temperature 350 °C, precursor concentration 0.2-0.3 M, etc.), pure NiO thin films crystallized in the cubic phase can be achieved only with NiCl₂ and Ni(NO₃)₂ precursors. These films have been post-annealed at 425 °C for 3 h either in room atmosphere or under vacuum. If all the films are p-type, it is shown that the NiO films conductivity and optical transmittance depend on annealing process. The properties of the NiO thin films annealed under room atmosphere are not significantly modified, which is attributed to the fact that the temperature and the environment of this annealing is not very different from the experimental conditions during spray deposition. The annealing under vacuum is more efficient. This annealing being proceeded in a vacuum no better than 10⁻² Pa, it is supposed that the modifications of the NiO thin film properties, mainly the conductivity and optical transmission, are related to some interaction between residual oxygen and the films.     

SiCN thin film prepared at room temperature by r.f. reactive sputtering

Silicon–carbon nitride (SiCN) thin films were deposited on Si substrate at room temperature by r.f. reactive sputtering. Fourier transform infrared spectroscopy (FTIR), optical absorption spectra (α(λ)) and electrical conductivity (σ) were studied for the thin films. The effect of the annealing on IR and σ was investigated at different temperatures. IR analysis indicates that Si–H, C–N, Si–C, Si–N, C–N and CN bonds are present in a-SiCN:H films. A shift of the stretching mode for Si–H bond to the high-wavenumber side is observed with increasing the nitrogen flow ratio γ_N2(=N₂/(Ar+H₂+N₂+CH₄)). The shift is from 2000 to 2190 cm⁻¹ when γ_N2=13.7%. The study shows that the film structure and optical and electrical properties are obviously modified readily by controlling the process parameters of deposition. The improvement in the film properties, e.g., good thermal stability, is explained mainly in terms of the cross-linked structure between the Si, C and N atoms.     

Annealing study of electrodeposited CuInSe<Subscript>2</Subscript> and CuInS<Subscript>2</Subscript> thin films

In this study CuInSe₂ and CuInS₂ thin films were prepared onto ITO glass substrate using the electrodeposition technique in aqueous solution. The electrodeposited films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray analysis. The annealing effects on electrodeposited precursors were investigated. The chalcopyrite structure of CuInSe₂/CuInS₂ showed an enhancement of crystallinity after subsequent selenization/sulfurization treatment in Se/S atmosphere, respectively. XRD and SEM studies revealed a dramatic improvement of the crystalline quality of CIS films after annealing treatments. Mott–Schottky measurements were used to assess the conductivity type of the films and their carrier concentration. The prepared samples underwent an etching process to remove the binary accumulated Cu_2?x(Se,S) phases shown in FESEM pictures. This etching process has shown a noticeable decrease in both, the flat band potential, V_fb (V), and the number of acceptors, N_A (cm^?3) in selenized CuInSe₂ and sulfurized CuInS₂ samples.     

The effects of thermal annealing on the obliquely deposited Ag-Ge-S thin films

Obliquely deposited thin films of ternary Ag-Ge-S glasses are characterized in this work. Thin films are fabricated in a vacuum thermal evaporator at different evaporation angles and examined by Raman spectroscopy. The Raman mode frequency of GeS₄ corner-sharing (CS) structure of the as-deposited films display a red-shift as a function of Ag content due to reduced global connectivity, and therefore decreased network stress. Film thickness of normally deposited thin films is significantly less when compared against obliquely deposited ones. Sulfur-ring (S₈) modes are observed in thin films but not in corresponding bulk material. Thermal annealing of thin films results in the disappearance of Sulfur-ring (S₈) modes, while the temperature required for this phenomenon is deposition angle dependent. Thickness of the obliquely deposited films shrinks significantly after thermal annealing, which indicates a collapse of the micro-column structure introduced by oblique deposition.     

Influence of air annealing on the structural, morphological, optical and electrical properties of chemically deposited ZnSe thin films

Zinc selenide nanocrystalline thin films are grown onto amorphous glass substrate from an aqueous alkaline medium, using chemical bath deposition (CBD) method. The ZnSe thin films are annealed in air for 4 h at various temperatures and characterized by structural, morphological, optical and electrical properties. The as-deposited ZnSe film grew with nanocrystalline cubic phase alongwith some amorphous phase present in it. After annealing metastable nanocrystalline cubic phase was transformed into stable polycrystalline hexagonal phase with partial conversion of ZnSe into ZnO. The optical band gap, E_g, of as-deposited film is 2.85 eV and electrical resistivity of the order of 10⁶-10⁷ Ω cm. Depending upon annealing temperature, decrease up to 0.15 eV and 10² Ω cm were observed in the optical band gap, E_g, and electrical resistivity, respectively.     

Towards a thin films electrochromic device using NASICON electrolyte

The optimisation of the morphology of WO₃ thin films allowed a more efficient electrochromic colouring using Na⁺ ions than H⁺ ones. Therefore, sodium superionic conductor (Na₃Zr₂Si₂PO₁₂, NASICON) films may be used as electrolyte in inorganic electrochromic devices. In this paper, the structure, chemical composition, morphology and electrochromic properties of WO₃, ZnO:Al and Na₃Zr₂Si₂PO₁₂ thin films were studied to develop a novel type of electrochromic device. WO₃, ZnO:Al and Na₃Zr₂Si₂PO₁₂ thin films were deposited using reactive magnetron sputtering of tungsten, zinc and aluminium and Zr–Si and Na₃PO₄ targets, respectively. For transparent conductive oxide coatings, a correlation was established between the deposition parametres and the film’s structure, transmittance and electrical resistivity. Classical sputtering methods were not suitable for the deposition of NASICON films on large surface with homogenous composition. On the other hand, the use of high-frequency pulsed direct current generators allowed the deposition of amorphous films that crystallised after thermal annealing upon 700 °C in the Na₃Zr₂Si₂PO₁₂ structure. Amorphous films exhibited ionic conductivity close to 2 × 10⁻³ S cm⁻¹. Finally, preliminary results related to the electrochromic performance of NASICON, WO₃ and indium tin oxide devices were given. Paper presented at the 11th EuroConference on the Science and Technology of Ionics, Batz-sur-Mer, France, Sept. 9–15, 2007.     

Structural and electrical characterization of strontium bismuth tantalate (SBT) thin films

Ferroelectric strontium bismuth tantalate (SBT) thin films were deposited by thermal metalorganic chemical vapour deposition (MOCVD) onto a complex layered Pt/IrO₂/Ir/Ti(Al)N substrate. A study of ultra-violet (UV)-assisted rapid thermal processing (RTP) annealing strategies of the SBT thin films was performed. The influence of UV irradiation temperature and annealing atmosphere on the crystallinity of the deposited films was evaluated using both microstructural and electrical analysis techniques. A UV-RTP strategy in an oxygen atmosphere above 400 °C, followed by a furnace treatment at 700 °C, provided an optimum remnant polarization figure of merit.     

Characterization of CuAlO2 thin film prepared by rapid thermal annealing of an Al2O3/Cu2O/sapphire structure

CuAlO₂ thin film was successfully prepared by rapid thermal annealing of an Al₂O₃/Cu₂O/sapphire structure in air above 1000 °C. The film was mostly with single crystalline structure as verified by X-ray diffraction methods. We found that crystal quality and electrical conductivity of the films were affected by the cooling rate after annealing. The highest conductivity obtained in this work was 0.57 S/cm. Optical gap of this film was determined to be 3.75 eV.     

Post-annealing effect upon optical properties of electron beam evaporated molybdenum oxide thin films

Molybdenum oxide (MoO₃) thin films were deposited by electron beam evaporation. The chemical composition, microstructure, optical and electrical properties of MoO₃ thin films depend on the annealing temperature and ambient atmosphere. X-ray diffraction (XRD) shows that crystalline MoO₃ films can be obtained at various post-annealing temperatures from 200 to 500 °C in N₂ and O₂. X-ray photoelectron spectroscopy (XPS) results reveal that the O-1s emission peak was shifted slightly toward lower binding energies as the annealing temperature in N₂ was increased. The oxygen vacancies and conductivity of MoO₃ film increased with the annealing temperature. However, when the MoO₃ films were annealed in an atmosphere of O₂, the optical transmission, the O/Mo ratio and the photon energy increased with the annealing temperature. The results differ from those for films annealed in a N₂ atmosphere.