Synthesis and effect of post-deposition thermal annealing on morphological and optical properties of ZnO thin film

Zinc oxide thin films have been deposited on glass substrates by the chemical bath deposition method; a surfactant, cetyltrimethylammonium bromide (CTAB); was used as capping agent. The films were annealed at two different temperatures: 200 and 300 °C. The structural features were investigated by X-ray diffraction analysis which exhibited hexagonal wurtzite structures along with c-axis orientations. Crystallite size was estimated and found to be around 33–41 nm. The effect of post-deposition thermal annealing on the morphological and optical properties has been investigated by scanning electron microscopy and photoluminescence spectra at room temperature. The band gap energies of uncapped and CTAB-capped ZnO films were found to be 3.28 and 3.48 eV, respectively.     

Effects of post-deposition annealing on chemical composition of SiNx film in SiO2/SiNx/SiO2/Si stacked structure

To systematically evaluate the quality of SiN_x films in multi-stacked structures, we investigated the effects of post-deposition annealing (PDA) on the film properties of SiN_x within the SiO₂/SiN_x/SiO₂/Si stacked structure by performing X-ray photoelectron spectroscopy (XPS), X-ray reflectivity (XRR), Fourier transform infrared (FT-IR) spectroscopy, and scanning transmission electron microscope–electron energy loss spectroscopy (STEM-EELS) analyses. The XPS results showed that PDA induces the oxidation of the SiN_x layer. In particular, new finding is that Si-rich SiN_x in the SiN_x layer is preferentially oxidized by PDA even in multi-stacked structure. The XRR results showed that the SiN_x layer becomes thinner, whereas the interface layer between the SiN_x layer and Si becomes thicker. It is concluded by STEM-EELS and XPS that this interface layer is SiON layer. The density of N–H and Si–H bonding within the stacked structure strongly depends on the PDA temperature. Our study helps elucidate the properties of SiN_x films in stacked structures from various perspectives.     

Effect of annealing temperature on titania thin films prepared by spin coating

Essentially fully dense titania thin films were spin coated on fused quartz substrates under identical conditions and subjected to annealing over the range 750°–900°C. The films were of a consistent ~400 nm thickness. The anatase → rutile phase transformation temperature was between 750°C and 800°C, with first-order kinetics; annealing at 900°C yielded single-phase rutile. Silicon contamination from the fused quartz substrate was considered to be critical since it suppressed both titania grain growth (maintaining constant grain size) and the phase transformation (occurring at an unusually high temperature); its presence also was considered to be responsible for the formation of lattice defects, which decreased the transmittances and the band gaps.     

Mononuclear precursor for MOCVD of HfO2 thin films

We report the precursor characteristics of a novel mononuclear mixed alkoxide compound [Hf(O(i)Pr)2(tbaoac)2] and its application towards MOCVD of HfO2 thin films in a production tool CVD reactor.     

Atomic layer deposition of crystalline molybdenum oxide thin films and phase control by post-deposition annealing

Molybdenum forms a range of oxides with different stoichiometries and crystal structures, which lead to different properties and performance in diverse applications. Herein, crystalline molybdenum oxide thin films with controlled phase composition are deposited by atomic layer deposition. The MoO₂(thd)₂ and O₃ as precursors enable well-controlled growth of uniform and conformal films at 200–275 °C. The as-deposited films are rough and, in most cases, consist of a mixture of α- and β-MoO₃ as well as an unidentified suboxide MoO_x (2.75 ≤ x ≤ 2.89) phase. The phase composition can be tuned by changing deposition conditions. The film stoichiometry is close to MoO₃ and the films are relatively pure, the main impurity being hydrogen (2–7 at-%), with ≤1 at-% of carbon and nitrogen. Post-deposition annealing is studied in situ by high-temperature X-ray diffraction in air, O₂, N₂, and forming gas (10% H₂/90% N₂) atmospheres. Phase-pure films of MoO₂ and α-MoO₃ are obtained by annealing at 450 °C in forming gas and O₂, respectively. The ability to tailor the phase composition of MoO_x films deposited by scalable atomic layer deposition method represents an important step towards various applications of molybdenum oxides.     

Transparent amorphous Indium-Gallium-Zinc-Oxygen thin film transistors using solution technology at low temperature

Transparent amorphous Indium-Gallium-Zinc-oxide thin films transistors (a-IGZO TFTs) were fabricated using spin-coating technique at a relative low annealing temperature of 300 °C. The effects of the gallium (Ga) concentration on the properties of the IGZO solutions, the optical properties of the a-IGZO films,and the a-IGZO TFTs device properties were researched. The a-IGZO thin films were uniform and smooth, root mean square roughness of IGZO films was less than 0.4 nm, and the transmittance was more than 80 % in the visible wavelength. The results showed that An appropriate amount of Ga doping and annealing temperature could significant improve the a-IGZO TFTs’ device performance. A saturation mobility of 0.04 cm² V^?1 s^?1 was obtained when the Ga concentration reached 10.7 %.     

退火气氛对掺银TiO2薄膜结构和光催化性能的影响

本文采用sol-gel法制备了掺银的TiO2/glass纳米光催化薄膜,并分别在空气和真空条件下对薄膜进行退火处理, 结构和光催化性能的测试结果表明, 退火气氛对薄膜的结构和薄膜对染料溶液的光催化降解效率都有影响。经真空退火处理的TiO2及Ag-TiO2薄膜较空气中退火处理的同样薄膜的光催化性能都低, 但适量掺银的Ag-TiO2薄膜的光催化活性较TiO2有不同程度的增强。     

Effect of thermal annealing on the microstructure of P3HT thin film investigated by RAIR spectroscopy

The influence of thermal annealing on the structural ordering and orientation rearrangement of as cast P3HT thin film (<100 nm) has been studied by reflection absorption infrared spectroscopy (RAIR). In order to erase the effect of temperature on the spectral intensity, two thermal procedures have been used to investigate the annealing-induced structural change of P3HT thin film. One is the continuous heating mode, in which the RIAR spectra were in situ collected during the heating process. The other is the stepwise heating mode, that is the isothermal annealing, and the spectra were ex situ collected at room temperature after the thermal treatment. It is found that thermal annealing can enhance the π–π interaction in P3HT crystal domain, whereas the improvement on the degree of crystallinity is not so obviously. Meanwhile, our results suggest that annealing-induced structural rearrangement on π–π stacking is irreversible, whereas the change on hexyl side chain packing is reversible.     

The dewetting dynamics of the polymer thin film by solvent annealing

The slippage effect of the polymer chains is investigated in the dewetting process of the polymer solution film. The solvent-induced dewetting is used in our experiments to study the dynamics of hole growth in the dewetting process of the polymer solution film. Our results show that in the case of the low molecular weight polystyrene (PS) film, the slippage effect of the polymer chains is not displayed and the radius of the holes is R approximately exp(t/tau); in the case of the higher molecular weight PS film, the slippage effect of the polymer chain is not valid in the case of the thin film and that is valid in the case of the thick film, and the dynamic process of hole growth divides into three stages (R approximately t, and then R approximately t(x) (23相似文献   

Influence of annealing temperature on microstructural and electrochemical properties of rf-sputtered LiMn2O4 film cathodes

The microstructural and electrochemical properties of rf-sputtered LiMn₂O₄ films were investigated as a function of post-deposition process. The degree of crystallization in the films gradually increased with the increase of annealing temperature (T _a). The films annealed at T _a?=?973 K exhibited characteristic peaks with predominant (111) orientation representing the cubic spinel structure of Fd3m symmetry. The estimated Mn–Mn and Mn–O distances obtained from the X-ray diffraction data were observed to be increased slightly with T _a. Characteristic changes in surface morphological features were observed as a function of T _a as evidenced from scanning electron microscopy. The estimated root mean square (RMS) roughness of the films increased from 97 to 161 nm with augmentation of T _a. The electrochemical studies, viz. cyclic voltammetry (CV), specific discharge capacity and Li ion diffusion coefficient were carried out for annealed LiMn₂O₄ films in saturated aqueous electrolyte (Li₂SO₄) in the potential window of 0–1.2 V and correlated with surface morphology and grain size. The LiMn₂O₄ films annealed at T _a?=?973 K exhibited better electrochemical performance and demonstrated a discharge capacity of about 53.5 μA h cm^?2 μm^?1 with diffusion coefficient of 1.2?×?10^?13 cm² s^?1.     

Predictive modeling and analysis of HfO2 thin film process based on Bayesian information criterion using PCA‐based neural networks

Principal component analysis (PCA)‐based neural network (NNet) models of HfO₂ thin films are used to study the process of efficient model selection and develop an improved model by using multivariate functional data such as X‐ray diffraction data (XRD). The accumulation capacitance and the hysteresis index input parameters, both characteristic of HfO₂ dielectric films, were selected for the inclusion in the model by analyzing the process conditions. Standardized XRD were used to analyze the characteristic variations for different process conditions; the responses and the electrical properties were predicted by NNet modeling using crystallinity‐based measurement data. A Bayesian information criterion (BIC) was used to compare the model efficiency and to select an improved model for response prediction. Two conclusions summarize the results of the research documented in this paper: (i) physical or material properties can be predicted by the PCA‐based NNet model using large‐dimension data, and (ii) BIC can be used for the selection and evaluation of predictive models in semiconductor manufacturing processes. Copyright © 2013 John Wiley & Sons, Ltd.     

Effects of deposition temperature and annealing temperature on the morphology and electrochemical capacitance of Ni(OH)2 thin films

In this paper, we report 3D nickel (II) hydroxide thin films with porous nanostructures prepared on Ni foam by direct current electrodeposition from aqueous solution of Ni(NO₃)₂ through basic chemicals. The effect of deposition temperature on Ni(OH)₂ thin film morphology is examined by field emission scanning electron microscopy, which is found to have significant influence on capacitance performance of Ni(OH)₂ thin films. Moreover, the effect of annealing temperature on electrochemical capacitance and long-time stability of Ni(OH)₂ thin films is investigated. An optimum-specific capacitance value of 2,447?farads?g^?1 is obtained for Ni(OH)₂ thin film deposited at 20?°C and annealed at 100?°C.     

Effect of morphology on organic thin film transistor sensors

This review provides a general introduction to organic field-effect transistors and their application as chemical sensors. Thin film transistor device performance is greatly affected by the molecular structure and morphology of the organic semiconductor layer. Various methods for organic semiconductor deposition are surveyed. Recent progress in the fabrication of organic thin film transistor sensors as well as the correlation between morphology and analyte response is discussed.     

Iron oxide nanotube film formed on carbon steel for photoelectrochemical water splitting: effect of annealing temperature

Carbon steels (CSs) were anodized in an ethylene glycol solution containing 3 vol.% H₂O and 0.1 m NH₄F to coat with nanotube arrays film. The as anodized nanotube arrays film were annealed in argon atmosphere at various temperatures ranging from 250 to 550 °C for 4 h. The morphology and crystal phases of the film developed after annealing processes were examined using field emission scanning electron microscopy, X‐ray diffraction. Morphology transforms from nanobube arrays to nanotube bundles at 250 °C, to nanobube bundles with nanoflakes at 350 and 450 °C, to nanotube bundles with nanobelts at 550 °C. Amorphous transformed completely into maghemite at 350 °C and hematite with minor magnetite at 450 and 550 °C. Diffuse reflectance ultraviolet and visible spectra revealed iron oxide nanotube film annealed at 350 °C, or higher than 350 °C behaved tremendous absorbance ability in visible spectra range. Mott–Schottky analysis and linear scan voltammetry were performed in 1 m NaOH to show that iron oxide nanotube film annealed at 450 °C exhibited best charge carrier transfer ability upon illumination and superior photoelectrochemical properties compared with the films annealed at other temperatures. The film annealed at 450 °C displayed the photocurrent density of 0.13 mA cm^?2 at 0.2 V_Ag/AgCl, but the film annealed at other temperatures with the photocurrent densities of lower than 0.05 mA cm^?2 at 0.2 V_Ag/AgCl. The morphology and phase transform of iron oxide nanotube film at different annealing temperature results in the change of their photoelectrochemical properties. Copyright © 2016 John Wiley & Sons, Ltd.     

Structural and electrical characteristics of ALD-HfO2/n-Si gate stack with SiON interfacial layer for advanced CMOS technology

We report the fabrication of an ultra-thin silicon oxynitride (SiON) as an interfacial layer (IL) for n-Si/ALD-HfO₂ gate stack with reduced leakage current. The XRD, AFM, FTIR, FESEM and EDAX characterizations have been performed for structural and morphological studies. Electrical parameters such as dielectric constant (K), interface trap density (D_it), leakage current density (J), effective oxide charge (Q_eff), barrier height (Φ_bo), ideality factor (ƞ), breakdown-voltage (V_br) and series resistance (R_s) were extracted through C-V, G-V and I-V measurements. The determined values of K, D_it, J, Q_eff, Φ_bo, ƞ, V_br and R_s are 14.4, 0.5 × 10 ¹¹ eV⁻¹ cm⁻², 2.2 × 10⁻⁹ A/cm², 0.3 × 10¹³ cm⁻², 0.42, 2.1, −0.33 and 14.5 MΩ respectively. SiON growth prior to HfO₂ deposition has curtailed the problem of high leakage current density and interfacial traps due to sufficient amount of N₂ incorporated at the interface.     

Synthesis of cobalt doped silica thin film for low temperature optical gas sensor

A modified sol–gel method was used to prepare cobalt doped silica thin film with a cobalt content of 10, 20 and 30 mol% (10Co, 20Co and 30Co). The prepared films were annealed at different temperatures in the range 400–1,000 °C, and their structural evolution examined. The mixed valence cobalt oxide, Co₃O₄, crystallizes only in the sample with the higher cobalt content, while cobalt silicate is the only crystalline phase detected in the sample 10Co and 20Co. Both the cobalt content and the temperature of heat treatment resulted to affect the nature of cobalt species dispersed in the silica matrix. The 30Co was selected for further investigations by FTIR spectroscopy to follow the structural evolution of 30Co film as function of the temperature and UV–Vis to get information on the cobalt valence state. The optical gas-sensing properties of 30Co films, containing Co₃O₄ as the major cobalt phase, were studied through the measuring of the film transmittance in dry air and in presence of dry air containing variable concentrations of polluting gases, CO and NO₂. The 30Co samples resulted to be highly sensitive to CO at room temperature. An explanation for the CO sensing characteristics, at low temperature, was proposed by referring to the physisorption-related mechanics of CO.     

Effect of fullerene coating on silicon thin film anodes for lithium rechargeable batteries

To improve the electrochemical performances of Si thin film anodes for lithium rechargeable batteries, fullerene thin films are prepared by plasma-assisted evaporation methods to be used as coating materials. Analyses via Raman and X-ray photoelectron spectroscopy indicate that amorphous polymeric films originated from fullerene are formed on the surface of the silicon thin film. The electrochemical performance of these fullerene-coated silicon thin film as an anode material for rechargeable lithium batteries has been investigated by cyclic voltammetry, charge/discharge tests, and electrochemical impedance spectroscopy. The fullerene-coated Si thin films demonstrated a high specific capacity of above 3,000 mAh g⁻¹ as well as good capacity retention for 40 cycles. In comparison with bare silicon anodes, the fullerene-coated silicon thin film showed superior and stable cycle performance which can be attributed to the fullerene coating layer which enhances the Li-ion kinetic property at the electrode/electrolyte interface.     

Effect of initial precursor concentration on TiO2 thin film nanostructures prepared by PCVD system

TiO₂ thin film was prepared on Si substrate by plasma chemical vapor deposition (PCVD) system and the morphologies of TiO₂ thin film were controlled by adjusting the initial precursor concentration. As the initial titanium tetra-isopropoxide (TTIP) concentration increases in PCVD reactor, the shapes of TiO₂ particles generated in PCVD reactor change from the spherical small-sized particles around 20 nm and spherical large-sized particles around 60 nm to aggregate particles around 100 nm. The TiO₂ particles with different shapes deposit on the substrate and become the main building blocks of resulting TiO₂ thin film. We observed the TiO₂ thin film with smooth morphology at low initial TTIP concentration, granular morphology at medium initial TTIP concentration, and columnar morphology at high initial TTIP concentration. It is proposed that we can prepare the TiO₂ thin film with controlled morphologies in one-step process just by adjusting the initial precursor concentration in PCVD.