Electrodeposition of SmS optical thin films on ITO glass substrate

SmS optical thin films were deposited on the surface of ITO glass with an electrodeposition method using aqueous solution containing SmCl₃·6H₂O and Na₂S₂O₃·5H₂O. The phase composition was analyzed by X-ray diffraction (XRD) and microstructure of the film was characterized by atomic force microscope (AFM). It is showed that SmS thin film could be obtained in the solution with n(Sm)/n(S) = 1:4, pH = 4.0 and annealing in Ar atmosphere at 200 °C for 0.5 h. The as-prepared thin films on the ITO glass exhibit a dense microstructure. The band gap of the thin film has been found to be 3.6 eV.     

Characterization of rubrene polycrystalline thin film transistors fabricated using various heat-treatment conditions

We observed the crystal structure changes of rubrene (5,6,11,12-tetraphenylnaphthacene) polycrystal thin films on SiO₂/Si(100) substrates at various heat-treatment temperatures by X-ray diffraction, and a near-field microwave microprobe technique. An amorphous rubrene thin film was initially observed at heat-treatment temperature of 35 °C. After the treatment with in-situ vacuum post-annealing at 80 °C for 22 h, the rubrene thin film was transformed from the amorphous phase into a crystalline phase of orthorhombic structure. We could obtain a higher field effect mobility of 0.047 cm²/V·s and lower threshold voltage of − 4 V for the following heat-treatment process: pre-annealing at 80 °C, cooling at 40 °C, and post-annealing at 80 °C for 22 h.     

The ferroelectric properties and residual stress analysis of Bi<Subscript>3.15</Subscript>Nd<Subscript>0.85</Subscript>Ti<Subscript>3</Subscript>O<Subscript>12</Subscript> thin films with a LaNiO<Subscript>3</Subscript> buffer layer

Bi_3.15Nd_0.85Ti₃O₁₂ (BNT) thin film with a thin LaNiO₃ film as buffer layer was fabricated by sol–gel method on Pt/TiO₂/SiO₂/Si substrate. The BNT thin films have a perovskite phase with a dense microstructure. The P _r and V _c value are 25.5 μc/cm² and 3.7 V, respectively under the applied voltage of 15 V. After the switching of 2 × 10⁹ cycles, the P _r value decreases to 86% of its pre-fatigue value. The leakage current density of the BNT thin films with LaNiO₃ buffer layer were generally in the order of 10⁻⁸ to 10⁻⁶ A/cm². The fatigue and leakage current properties were improved dramatically compared with the BNT film without a LaNiO₃ buffer layer that we prepared before. The measured residual stress was tensile stress and its value was 176 MPa.     

Thin film fabrication of nano-porous 12CaO·7Al2O3 crystal and its conversion into transparent conductive films by light illumination

Thin film fabrication of crystalline 12CaO·7Al₂O₃ (C12A7) with zeolitic structure was examined, and their electrical and optical properties were measured. Polycrystalline thin films were prepared by post-annealing of amorphous films in oxygen atmosphere at temperatures above 800 °C. Choice of substrates was crucial for obtaining single-phase thin films. Although various oxide substrates (single crystals of Al₂O₃, Y-stabilized ZrO₂, MgO and silica glass) were examined, single-phase films were obtained only for MgO substrates and the other substrates reacted with the CaO component in the films during post-annealing. The optical band gap of C12A7 was evaluated to be 5.9 eV. Hydride ions were incorporated into the film by a thermal treatment in a hydrogen atmosphere at 1200 °C. The resulting transparent thin films were converted into transparent persistent electronic conductors exhibiting an electrical conductivity 6.2×10⁻¹ S cm⁻¹ at 300 K by ultraviolet light illumination. This is the first example of transparent conductive thin film in which conductive areas can be patterned directly by light.     

Thick and Dense Anodic Oxide Layers Formed on Aluminum in Sulphuric Acid Bath

Thick and dense oxide layers were obtained on aluminium in sulphuric acid electrolyte. For this purpose, the methodology of experimental design was used. A three-variables Doehlert design (bath temperature, anodic current density, sulphuric acid concentration), was achieved. In order to maximize the growth rate and the density of the anodic oxide layer, optimum path study was conducted. Under the determined optimal anodizing conditions (5.7℃, 3 A·dm -2 , C sul =140 g·L -1 ), the estimated response values we...     

Structural and electrical characteristics of chemical solution derived (Bi3.2La0.4Nd0.4)Ti3O12 thin films

(Bi_3.2La_0.4Nd_0.4)Ti₃O₁₂ (BLNT) thin films were prepared on Pt/Ti/SiO₂/Si substrates by using chemical solution deposition technique, and the effects of annealing temperatures in the range of 550-750 °C on structure and electrical properties of the thin films were investigated. X-ray diffraction analysis shows that the thin films have a bismuth-layered perovskite structure with preferred (117) orientation. The surface morphology observation by field-emission scanning electron microscopy confirms that films are dense and smooth with uniformly distributed grains. The grain size of the thin films increases with increasing annealing temperature; meanwhile, the structural distortion of the thin films also increases. It was demonstrated that the thin films show good electrical properties. The dielectric constant and dielectric loss are 191 and 0.028, respectively, at 10 kHz for the thin film annealed at 600 °C, and the 2Pr value of the thin film annealed at 700 °C is 20.5 μC/cm² at an electric field of 500 kV/cm.     

Structural evaluation of sol-gel derived lead strontium titanate diffusion barrier for integration in lead zirconate titanate transducer design

Sol-gel derived Pb₄₀Sr₆₀TiO₃ (PST) thin film has been investigated as a diffusion barrier for integrating in PbZr₃₀Ti₇₀O₃ (PZT) device structures on Si substrates. PST film was deposited on SiO₂/Si substrate and annealed at a relatively low temperature range of 550-600 °C producing a crack-free, smooth and textured surface. Following deposition on PST/SiO₂/Si template PZT thin film was crystallised exhibiting random grain orientations and an insertion of the bottom Pt/Ti electrode forming PZT/Pt/Ti/PST/SiO₂/Si stacks promoted the preferred PZT (111) perovskite phase. PZT (111) peak intensity gradually decreased along with slight increase of the PZT (110) peak with increasing annealing temperature of the buffer PST film. The dielectric and ferroelectric properties of the PZT with barrier PST deposited at 550 °C were assessed. The dielectric constant and loss factor were estimated as 390 and 0.034 at 100 kHz respectively and the remnant polarisation was 28 µC/cm² at 19 V. The performance of the PZT/PST device structures was compared to similar PZT transducer stacks having widely used barrier TiO₂ layer.     

Epitaxial growth and electrical measurement of single crystalline Pb(Zr0.52Ti0.48)O3 thin film on Si(001) for micro-electromechanical systems

We report in this work the epitaxial growth and the electrical characteristics of single crystalline Pb(Zr_0.52Ti_0.48)O₃ (PZT) thin film on SrTiO₃(STO)-buffered Si(001) substrate. The STO buffer layer deposited by molecular beam epitaxy allows a coherent oxide/Si interface leading enhanced PZT crystalline quality. 70 nm-thick PZT (52:48) layer was then grown on STO/Si(001) by sol-gel method. X-ray diffraction demonstrates the single crystalline PZT film on Si substrate in the following epitaxial relationship: [110] PZT (001)//[110] STO (001)//[100] Si (001). The macroscopic electrical measurements show a hysteresis loop with memory window of 2.5 V at ± 7 V sweeping range and current density less than 1 μA/cm² at 750 kV/cm. The artificial domains created by piezoresponse force microscopy with high contrast and non-volatile properties provide further evidence for the excellent piezoelectric properties of the single crystalline PZT thin film.     

Rapid thermal-plasma annealing of ZnO:Al films for silicon thin-film solar cells

Rapid thermal annealing of sputter-deposited ZnO and Al-doped ZnO (AZO) films with and without an amorphous silicon (a-Si) capping layer was investigated using a radio-frequency (rf) argon thermal plasma jet at atmospheric pressure. The resistivity of bare ZnO films on glass decreased drastically from 10⁶ to 10³ Ω·cm at maximum surface temperatures T_max above 650 °C, whereas the resistivity increased from 10^− 4 to 10^− 3-10^− 2 Ω·cm for bare AZO films. On the other hand, the resistivity of AZO films with a 30-nm-thick a-Si capping layer remained below 10^− 4 Ω·cm, even after TPJ annealing at a T_max of 825 °C. X-ray diffraction and X-ray photoemission electron studies revealed that the film crystallization of both AZO and a-Si layers was promoted without the formation of an intermixing layer. Additionally, the crystallization of phosphorous- and boron-doped a-Si layers at the sample surface was promoted, compared to that of intrinsic a-Si under identical plasma annealing conditions. The role of the a-Si capping layer on sputter-deposited AZO and ZnO films during TPJ annealing is demonstrated. The effects of the mixing of phosphorous and boron impurities in a-Si:H during TPJ annealing of flat and textured AZOs are also discussed.     

The join calcium monoaluminate-calcium fluoride

The system CaO-Al₂O₃-CaF₂ is important in cement and slag technology and in metallurgy. A section of this system, the pseudo-binary join CaO·Al₂O₃-CaF₂, has been studied and the phase diagram established. This join is of particular interest since CaO·Al₂O₃ is one of the main constituents of high alumina cement.Quenching in sealed platinum capsules followed by microscopic and X-ray examination was the principal method used. The only compound on the join is 3CaO·3Al₂O₃·CaF₂ which melts congruently at 1507±1.5° C and forms one eutectic with CaO·Al₂O₃ at 11% CaF₂ and 1498±5° C and another with CaF₂ at 97.5% CaF₂ and 1405±10° C. There is a wide zone of liquid immiscibility. The m.p. of CaF₂ was determined to be 1422±1° C.Attempts to use high temperature microscopy to study this system are described.     

Overview about the optical properties and mechanical stress of different dielectric thin films produced by reactive-low-voltage-ion-plating

Thin films of Ta₂O₅, Nb₂O₅, and HfO₂ were deposited by reactive-low-voltage-ion-plating (RLVIP) on unheated glass and silicon substrates. The film thickness was about 200 nm. Optical properties as well as mechanical film stress of these layers were investigated in dependence of various deposition parameters, i.e. arc current and oxygen partial pressure. For an arc current in the range between 40 and 50 A and an oxygen partial pressure of at least 11 · 10^− 4 mbar good results were obtained. The refractive index and film thickness were calculated from spectrophotometric transmission data using the Swanepoel theory. For example at 550 nm wavelength the refractive index for thin RLVIP-Nb₂O₅-films was found to be n₅₅₀ = 2.40. The optical absorption was obtained by photo-thermal deflection spectrometry. For the investigated materials absorption coefficients in the range of k = 5 · 10^− 4 at 515 nm wavelength were measured. The mechanical film stress was determined by measuring the difference in bending of silicon substrates before and after the deposition process. For dense films, i.e. no water vapour sorption on atmosphere, the mechanical film stress was always compressive with values of some hundred MPa. In case of films deposited with higher arc currents (I_arc > 60A) and lower oxygen pressure (< 15 · 10^− 4 mbar) the influence of a post deposition heat treatment at 350 °C for 4 h on air was also investigated. For these films the properties could clearly be improved by such treatment. However, by using lower arc currents and higher oxygen partial pressure during the ion plating process, immediately dense and environmental stable films with good optical as well as mechanical properties could be achieved without post deposition heat treatment. All the results obtained will be presented in graphs and diagrams.     

Preparation and characterization of novel CuClSe2 semiconductor thin film

CuClSe₂ was synthesized by solid-state reaction between copper chloride and selenium at 300 °C. CuClSe₂ thin film was prepared on a glass substrate by pulsed laser deposition (PLD) method. XRD (X-ray diffraction) analysis revealed that the CuClSe₂ thin film has a preferred surface orientation parallel to (006). The transmittance and reflectance spectra of the film indicated that the compound is an indirect band gap material; the energy band gap is about 1.45 eV; its absorption coefficients are in the range of 10⁴-10⁵ cm^− 1 when the wavelength is shorter than 720 nm. The melting point of CuClSe₂ is about 328 °C. These results show that CuClSe₂ is a potential absorber layer material applied in solar cells.     

Effect of processing temperature on characteristics of metal-ferroelectric (BiFeO3)-insulator (HfLaO)-silicon capacitors

The effect of temperature in rapid thermal annealing (RTA) process on the physical and electrical properties of bismuth ferrite ceramic thin films on HfLaO/p-Si substrates has been investigated. In metal-ferroelectric-insulator-silicon (MFIS) capacitors, the high-k HfLaO dielectric layer was prepared as the insulator layer. On HfLaO/Si substrates the bismuth ferrite thin film was fabricated via sputtering process with a BiFeO₃ (BFO) target at room temperature followed by RTA. The RTA temperature ranged from 500 to 700 °C. It is found that the root mean square roughness of ceramic films increases for high-temperature process. The maximum ferroelectric memory window is 1.6 V obtained from a sweep voltage of ± 4 V at the lowest RTA temperature of 500 °C. This good ferroelectric memory performance can be attributed to the low leakage current as a result of smooth surface of nanocrystalline ferroelectric BFO and Bi₂Fe₄O₉ thin films.     

Influence of annealing on characteristics of tin disulfide thin films by vacuum thermal evaporation

In this paper, we reported on an approach to prepare tin disulfide (SnS₂) thin films on soda-lime glass substrates by vacuum thermal evaporation using SnS₂ powders as a source. The influence of annealing on the chemical composition, crystal structure, surface morphology, and optical band gap of the SnS₂ thin films was systemically investigated. The as-grown SnS₂ thin film was amorphous, homogeneous, smooth, nearly stoichiometric, with no pinhole and crack free, and with an optical band gap of 2.41 eV. After the SnS₂ thin film was annealed at 300 °C, the crystallization of SnS₂ was demonstrated by X-ray diffraction and scanning electron microscope with a characteristic of a preferred orientation along (001) plane with hexagonal phase and the sheet appearance of the SnS₂ crystals. At the annealing temperature of 350 °C, some SnS₂ crystallites and a few pinholes appeared on the surface of the SnS₂ thin films, though the SnS₂ thin film was not oxidized. When the annealing temperature was increased to 400 °C, SnS₂ was gradually oxidized into an approximate spherical shape of SnO₂ from the top to the bottom of the SnS₂ thin film by trace O₂ in the furnace. Therefore, our experiment suggested that the annealing temperature of the SnS₂ thin film using the vacuum thermal evaporation should not be over 300 °C as a window layer in compound thin film solar cells.     

Characterization and optoelectronic properties of sol-gel-derived CuFeO2 thin films

In this study, CuFeO₂ thin films were deposited onto quartz substrates using a sol-gel and a two-step annealing process. The sol-gel-derived films were annealed at 500 °C for 1 h in air and then annealed at 600 to 800 °C for 2 h in N₂. X-ray diffraction patterns showed that the annealed sol-gel-derived films were CuO and CuFe₂O₄ phases in air annealing. When the films were annealed at 600 °C in N₂, an additional CuFeO₂ phase was detected. As the annealing temperature increased above 650 °C in N₂, a single CuFeO₂ phase was obtained. The binding energies of Cu-2p_3/2, Fe-2p_3/2, and O-1s were 932.5 ± 0.1 eV, 710.3 ± 0.2 eV and 530.0 ± 0.1 eV for CuFeO₂ thin films. The chemical composition of CuFeO₂ thin films was close to its stoichiometry, which was determined by X-ray photoelectron spectroscopy. Thermodynamic calculations can explain the formation of the CuFeO₂ phase in this study. The optical bandgap of the CuFeO₂ thin films was 3.05 eV, which is invariant with the annealing temperature in N₂. The p-type characteristics of CuFeO₂ thin films were confirmed by positive Hall coefficients and Seebeck coefficients. The electrical conductivities of CuFeO₂ thin films were 0.28 S cm^− 1 and 0.36 S cm^− 1 during annealing at 650 °C and 700 °C, respectively, in N₂. The corresponding carrier concentrations were 1.2 × 10¹⁸ cm^− 3 (650 °C) and 5.3 × 10¹⁸ cm^− 3 (700 °C). The activation energies for hole conduction were 140 meV (650 °C) and 110 meV (700 °C). These results demonstrate that sol-gel processing is a feasible preparation method for delafossite CuFeO₂ thin films.     

Growth morphology study of cathodically electrodeposited Fe3O4 thin films at elevated temperatures

We investigated the electrodeposition of Fe₃O₄ thin films in the Fe³⁺-triethanolamine system by galvanostatic deposition at elevated temperatures. It was found that with a fixed current density, the concentration of Fe³⁺ ions had a significant impact on the electrodeposition rate, while the deposition temperature and time strongly affected the morphology of the Fe₃O₄ thin films. Fe₃O₄ thin films deposited in electrolyte with high Fe³⁺ concentration and at high temperature (>80 °C) exhibited a dense and uniform morphology and were composed of globular or polyhedral crystallites, while the Fe₃O₄ thin films deposited at low temperatures (<70 °C) were loose and flake-like. Based on the empirical observations, a hypothetical growth model for the electrodeposition of Fe₃O₄ at elevated temperatures was proposed.     

Plastic substrate with gas barrier layer and transparent conductive oxide thin film for flexible displays

A novel plastic substrate for flexible displays was developed. The substrate consisted of a polycarbonate (PC) base film coated with a gas barrier layer and a transparent conductive thin film. PC with ultra-low intrinsic birefringence and high temperature dimensional stability was developed for the base film. The retardation of the PC base film was less than 1 nm at a wavelength of 550 nm (film thickness, 120 µm). Even at 180 °C, the elastic modulus was 2 GPa, and thermal shrinkage was less than 0.01%. The surface roughness of the PC base film was less than 0.5 nm. A silicon oxide (SiO_x) gas barrier layer was deposited on the PC base film by a roll-to-roll DC magnetron reactive sputtering method. The water vapor transmission rate of the SiO_x film was less than 0.05 g/m²/day at 40 °C and 100% relative humidity (RH), and the permeation of oxygen was less than 0.5 cc/m² day atm at 40 °C and 90% RH. As the transparent conductive thin film, amorphous indium zinc oxide was deposited on the SiO_x by sputtering. The transmittance was 87% and the resistivity was 3.5 × 10^− 4 ohm cm.     

Ultra-fast boriding of nickel aluminide

In this study, we explored the possibility of ultra-fast electrochemical boriding of nickel aluminide (Ni₃Al) in a molten borax electrolyte. Electrochemical boriding was performed at 950 °C for 15 min and at current densities ranging from 0.1 to 0.5 A/cm². The boride layers formed on the test samples were 50 to 260 μm thick depending on the current density. The mechanical, structural, and chemical characterization of the boride layers was carried out using a Vickers micro-hardness test machine, optical and scanning electron microscopes, and a thin film X-ray diffractometer. The hardness of boride layer was in the range from 800 to 1200 ± 50 HV depending on the load and the region from which the hardness measurements were taken. X-ray diffraction studies confirmed that the boride layers were primarily composed of Ni₃B, Ni₄B₃ and Ni₂₀AlB₁₄ phases. Structurally, the boride layer was very homogenous and uniformly thick across the borided surface area.     

Characterization of TiO2 thin films prepared by electrolytic deposition for lithium ion battery anodes

The electrolytic deposition of TiO₂ thin films on platinum for lithium batteries is carried out in TiCl₄ alcoholic solution and the films are subsequently annealed. The as-prepared films are amorphous TiO(OH)₂·H₂O, transformed into anatase TiO₂ at 350 °C, and then gradually into rutile TiO₂ at 500 °C. Cyclic voltammograms show oxidation and reduction peaks at 2.20 and 1.61 V, respectively, corresponding to charge and discharge plateaus at 1.98 and 1.75 V vs. Li⁺/Li. The specific capacity decreases with increasing current density for film of 128-nm thickness in the initial discharge. It is observed that the diffusion flux of Li⁺ insertion/extraction into/from TiO₂ controls the reaction rate at higher current densities. Consequently, at low film thickness, high discharge capacity (per weight) is found for the initial cycle at a current density of 10 μA cm^− 2. However, the capacity of prepared films in various thicknesses approach 103 ± 5 mAh g^− 1 after 50 cycles, since the formation of cracks for thicker films offers shorter diffusion paths for Li⁺. In addition, TiO₂ films show electrochromic properties during lithiation and delithiation.     

Structural and luminescence correlation of annealed Er-ZnO/Si thin films deposited by AACVD process

Er doped ZnO thin films have been synthesized from zinc acetates dihydrate (C₄H₆O₄Zn·2H₂O) and Erbium tris (2,2,6,6-tetramethyl-3,5-heptadionate) (Er(TMHD)₃) by aerosol assisted chemical vapor deposition AACVD atmospheric pressure technique. Films were deposited in the temperature range of [370–500 °C] on Si (1 1 1) substrate. Nano-disk shaped grains were grown on the top of the film surface. The morphology of the as-deposited films was found to be dependent on the substrate temperature. After annealing in air atmosphere, XRD patterns revealed a highly oriented c-axis Er:ZnO films with hexagonal wurtzite structure without any second phase. Under 488 nm excitation, the intra 4f–4f green emission (²H_11/2, ⁴S_3/2 → ⁴I_15/2 transitions) gradually increased with increasing annealing temperature. Also, the local structure of Er changes to a pseudo-octahedral structure with C_4v symmetry. The ZnO film with 2.504 at.% Er³⁺ doping has the best crystalline structure and the best resolved PL spectra. Using 325 nm excitation, all the samples showed an ultraviolet emission centered at 380 nm originating from a near band EDGE emission and a broad band green emission centered at 520 nm from deep levels. The optical response was correlated with crystallinity of the synthesized thin films.