Influencing FTO thin film growth with thin seeding layers: a route to microstructural modification (original) (raw)
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Preparation and characterization of sprayed FTO thin films
The European Physical Journal Applied Physics, 2007
Fluorine doped tin oxide (FTO) thin films have been prepared by spray pyrolysis technique with no further annealing. Films with 2.5% of fluorine grown at 400 • C present a single phase and exhibit a tetragonal structure with lattice parameters a = 4.687Å and c = 3.160Å. Scanning electron micrographs showed homogeneous surfaces with average grain size around 190 nm. The films are transparent in the visible zone and exhibit a high reflectance in the near infrared region. The best electrical resistivity was 6.3 × 10 −4 Ω cm for FTO with 2.5% of fluorine. The ratio of transmittance in the visible to the sheet resistance are in the 0.57 × 10 −2-1.96 × 10 −2 Ω −1 range.
Selective light induced chemical vapour deposition of titanium dioxide thin films
Light Induced Chemical Vapour Deposition (LICVD) of titanium dioxide thin films is studied in this work. It is shown that this technique enables to deposit locally and selectively a chosen crystalline phase with a precise controlled thickness at low substrate temperature, allowing even the use of polymer substrates. the case of polymer substrates, the fluence had to be kept below 15 mJ/cm 2 not to damage or ablate the polymers, resulting in very low growth rates (in the order of 10-3 nm/pulse). In these conditions, only amorphous films with about 10% of carbon contamination could be obtained. Additionally, films were shown to crack above a certain deposited thickness, which is attributed to thermal effects. As a matter of fact, calculations showed a high temperature rise up to 70°C of the polymer/oxide interface. Deposition on polymers coated with transparent conductive oxide was also demonstrated.
Light induced chemical vapour deposition of titanium oxide thin films at room temperature
Applied Surface Science, 2000
. High resolution patterned deposition of titania is achieved by light induced chemical vapour deposition LICVD , by Ž . imaging a mask onto a glass substrate. A long pulse XeCl Excimer laser 308 nm provides, by perpendicular irradiation, the Ž . energy to convert titanium tetraisopropoxide TTIP vapour into titanium dioxide films, in an oxygen atmosphere, on unheated glass substrates. The amorphous titania deposits contain about 6% carbon contamination according to X-ray Ž . photoelectron spectroscopy XPS measurements. The deposition rate increases with increasing laser fluence until a maximum value is reached, then remains constant over a wide range, and finally decreases with further fluence increase due to titania ablation or thermal effects. The film thickness increases linearly with the number of pulses after a nucleation period. The strong influence of the laser pulse repetition rate on the growth rate and the thickness profile are reported. q
Investigation of the low temperature atmospheric deposition of TCO thin films on polymer substrates
Surface and Coatings Technology, 2004
Atmospheric barrier-torch discharge was used for low temperature deposition of thin conductive oxide thin films on polymer substrates. An atmospheric high-density plasma jet was excited at the outlet of the quartz nozzle with an external metallic ring electrode. The RF power was capacitively connected to the plasma via a dielectric wall of the quartz tube. There was not a direct contact of the atmospheric plasma with the metallic electrode in this configuration. In O and SnO transparent and conductive x y x thin films were deposited on polymer, quartz and silicon substrates by this technique. Vapours of solid phase of In-acetylacetonate and Sn-acetylacetonate carried by nitrogen flow were used for deposition of In O and SnO thin films, respectively and vapours x y x prepared of liquid solutions of In-tetramethylheptanedionate in n-Oktan. Some atmospheric plasma jet parameters were determined 3 by emission spectroscopy and by planar Langmuir probe. Deposited films were analysed by means of electron microprobe system, XRD diffraction and electrical conductivity measurement.
Chemical vapor deposition of doped TiO2 thin films
Thin Solid Films, 1987
Niobium-, tantalum-and fluorine-doped TiO, films were made by atmospheric pressure chemical vapor deposition from titanium alkoxides mixed with niobium ethoxide, tantalum ethoxide and t-butyl fluoride respectively. 4% H, in N, was used as the carrier gas and the deposition temperatures were in the range 400-600 "C. The resistivities of the films increased dramatically with film thickness. For highly doped films 1 urn thick resistivities as low as 0.01 Zz cm were achieved.
Thin Solid Films, 2005
Ta 2 O 5 thin films were produced by metallo-organic low pressure chemical vapor deposition using Tantalum(V) Tetraethoxydimethylaminoethoxide (TaC 12 H 30 O 5 N) as precursor. This liquid precursor at room temperature makes it possible to deposit thin films of Ta 2 O 5 on wafer batches of up to 35 wafers. In this communication, we report on the processing and equipment development to achieve batch fabrication, and on the optimization of the deposited thin films properties for their application in microsystems. An evaporator was linked to a horizontal hot wall furnace. The deposition of Ta 2 O 5 was performed at 425 -C and the influence of a post-annealing at higher temperatures on the chemical, electrical and optical properties of the films was evaluated. Annealing treatments in oxygen were found to reduce the amount of residual carbon and hydrogen in the films. An annealing in oxygen followed by an annealing in forming gas was used to improve the charge levels and hysteresis. The optical properties of the amorphous Ta 2 O 5 films varied slightly with the annealing treatment. Annealing the films at a temperature of 700 -C and higher caused their crystallization, leading to a decrease of their optical bandgap. The processed films have found applications in microsystems as chemical resistant coatings, optical coatings for wave guides, and chemical sensitive layers for Ion-Sensitive Field-Effect Transistors.
Journal of Alloys and Compounds, 2019
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Spray pyrolysis deposition and characterization of titanium oxide thin films
Materials Chemistry and Physics, 2003
Titanium oxide films were deposited by the ultrasonic spray pyrolysis process using titanium oxide acetylacetonate (TAAc) as source material dissolved in pure methanol. As-deposited films show the anatase crystalline structure, while annealed samples at 850 • C have the rutile phase. Rutherford backscattering measurements indicate that the deposited films are formed by stoichiometric TiO 2 material. Root-mean-square (rms) roughness depends on the substrate temperature and on the annealing process. Refractive index has values of the order of 2.36 for as-deposited films and 2.698 for annealed films. This change is associated with the anatase to rutile phase change. IR analyses show well-defined absorption peaks located at 433 and 638 cm −1 for anatase phase and peaks located at 419, 466, 499 and 678 cm −1 for rutile phase. In general, the titanium oxide films show high optical transmission. The energy band gap calculated for the anatase phase is of the order of 3.4 eV. The current density-electric field characteristics of MOS structures show current injection across the titanium oxide film even for low applied electric fields. However, electric breakdown was not observed for applied fields up to 5 MV cm −1 .