| Titre : | Synthesis and characterization of Zinc Oxide (ZnO) Thin films deposited by spray pyrolysis for applying: electronics and photonics |
| Auteurs : | Mohamed Othmane, Auteur ; Abdallah Attaf, Directeur de thèse |
| Type de document : | Thése doctorat |
| Editeur : | Biskra [Algérie] : Faculté des Sciences Exactes et des Sciences de la Nature et de la Vie, Université Mohamed Khider, 2018 |
| Format : | 1 vol. (116 p.) / 30 cm |
| Langues: | Anglais |
| Résumé : |
In our study we were deposited a transparent oxide conducting thin films by two different methods the first one is the pneumatic spray pyrolysis and the second one is the ultrasonic spray pyrolysis, for investigating on five factors and thier effect on zinc oxide thin films characteristics. In the pneumatic spray pyrolysis we have deposited undoped zinc oxide thin films for checking on the effect of spraying flow rate and the deposition air pressure. In the ultrasonic spray pyrolysis we have divided our study into two parts the first was for studying the effect of substrate temperature on the undoped zinc oxide thin films properties the second part was for studying how much the extent of the dopants effect aluminum and fluorine on the zinc oxide thin films. The whole of the zinc oxide thin films were analyzed by many different techniques X-ray diffraction, scanning electron microscopy UV-Vis, Hall effect, four and two probes technique. in the pneumatic spray method we have observed that the films the films processed at 0.5 up to 1.5 bar showed optical band gap of about 3.3965 with electrical conductivity of 0.9×103 (Ω.cm)-1, The X-ray diffraction spectrum indicated that the films were crystalline with hexagonal structure with the only diffraction peak (002).We conclude that there is a very important factor to get the best properties between deposition air pressure and solution flow rate. In the second part we observed that the appropriate substrate temperature is 350° for getting good reaction on top of the substrate, in addition to that the XRD patterns showed that the ZnO films have polycrystalline nature and a hexagonal wurtzite structure with (100) and (002) preferential orientation at high temperature, where the electrical conductivity of ZnO films was increased from 3.87×10-3 (Ω.cm)-1 to41.58 (Ω.cm)-1. As well in the study of aluminum doping ZnO, the X-ray diffraction and SEM analysis exhibited that the AZO films were found polycrystalline structure with a hexagonal wurtzite structure along the (002) growth orientation, moreover there is a decreasing in the optical band gap from 3. 38 to 3. 27 eV, the lowest resistivity (2.32 × 10-3 Ω.cm) was observed for AZO films processing with 5 at% ratio. In addition the effect of fluorine doping on ZnO thin films properties is obvious in our study. Where the FZO films showed that the films have peaks correspond to the hexagonal wurtzite structure of ZnO. Where the intense diffraction peak is the (002),the whole of FZO films become denser after 2 at% of fluorine, in the electrical study, we observed that, the electrical conductivity increasing as the fluorine doping increases, where the highest value is 1,68×102 (Ω.cm )-1 at 5 at% of fluorine doping. |
| Sommaire : |
Acknowledgement..................................I Liste of Tables..............II Liste of figures..............III General Introduction.1 Chapter I : Transparent Conductive Oxides I.1.Transparent conducting oxides...........................4 I.2.Trends in the development of TCO materials...................................................5 I.3.Zinc Oxide (ZnO) Properties...............................6 I.3.1.Basic informations.....6 I.3.2.Structural Properties..7 I.3.3.Optical Properties......9 I.3.4.Electrical properties...10 I.4.Review of doped zinc oxide thin films...............11 I.5.Major Applications of zinc oxide thin films....11 I.6.Thin Film Deposition Techniques......................12 I.6.1.Physical Vapour deposition...........................................14 I.6.2.Pulsed Laser Deposition (PLD).....................................15 I.6.3.Chemical Vapor Deposition (CVD)..............................16 I.6.4.Wet Chemical Sol-gel..................................................17 I.6.5.Spray Pyrolysis..........19 I.6.5.1.working principle...19 I.6.5.2.Advantages of Spray Pyrolysis Technique.................21 I.7.Refrences..................22 Chapter II : Realization and characterization Of thin films II.1.Introduction...........26 II.2.Decomposition of precursor................................27 II.3.Spray pyrolysis system set-up............................28 II.3.1.Empirical conditions..30 II.3.2.Empirical details.......30 II.3.2.1.Pneumatic spray pyrolysis.........................................30 • Section one.............30 • Section two.............30 II.3.2.2.Ultrasonic spray pyrolysis.........................................31 • Part one..................31 • Part two..................32 II.4.Characterization methods....................................34 II.4.1.Microstructural and Phase Characterization.................34 II.4.1.1.Scanning electron microscope SEM..........................34 II.4.1.2.Energy despersive X ray-spectroscopy......................36 II.4.1.3.X-ray diffraction....38 II.4.2.Thickness measurement...............................................40 II.4.2.1. Measurement by Scanning electron microscopy......40 II.4.2.2.Optical interference....................................................41 II.4.2.3. Weight difference method................42 II.4.2.4.Profilometry............42 II.4.3.Stress measurement..43 II.4.3.Optical transmittance...................................................44 II.4.4.Electrical characterization techniques...........................46 II.5.References...................52 Chapter III : Effect of solution flow rate and deposition air pressure on ZnO properties deposited using Pneumatic Spray Pyrolysis III.1.Pneumatic spray pyrolysis.................................54 III.1.1.Section one - Effect of solution flow rate................54 III.1.1.1.Thickness calculation................................................54 III.1.1.2.Structural properties..................................................55 III.1.1.3.Optical properties..59 III.1.1.4. The electrical conductivity of ZnO thin films.........62 III.1.2.Section two - Effect of deposition air pressure.......63 III.1.2.1.Thickness calculation................................................63 III.1.2.2.Structural properties..................................................64 III.1.2.3.Optical properties..68 III.1.2.4. The electrical conductivity of ZnO thin films..........71 III.2.Conclusion............72 III.3.References............73 Chapter IV : Effect of substrate temperature and dopants on ZnO properties deposited using Utrasonic spray pyrolysis IV.1 Ultrasonic spray pyrolysis.................................75 IV.1.1. Part one- Effect of substrate temperature T°C.....75 IV.1.1.1. The growth rate calculation.....................................75 IV.1.1.2.The crystalline structure of ZnO thin films.....76 II.4.4.1.Four probes technique................................................46 II.4.4.2.Two probes technique................................................48 II.4.5.Hall measurement......49 IV.1.1.3.The microstructural and morphology properties.....80 IV.1.1.4.The optical properties of ZnO thin films.................82 IV.1.1.5.The electrical conductivity of ZnO thin films..........85 IV.1.1.6.Conclusion............87 IV.1.2.Part two - Effect of dopants on ZnO thin films......88 IV.1.2.1.Effect of Aluminum doping on ZnO thin films...89 IV.1.2.1.1.Thickness calculation............................................89 IV.1.2.1.2.The crystalline structure of ZnO : Al thin films...90 IV.1.2.1.3.The microstructural and morphology properties..94 IV.1.2.1.4.The optical properties of ZnO :Al thin films........99 IV.1.2.1.5.The electrical conductivity of ZnO :Al thin films.101 IV.1.2.1.6.Conclusion.........102 IV.1.2.2.Effect of fluorine doping on ZnO thin films.........103 IV.1.2.2.1.Thickness calculation............................................103 IV.1.2.2.2.The crystalline structure of ZnO :F thin films.......104 IV.1.2.2.3.The optical properties of ZnO :F thin films...........108 IV.1.2.2.4.The electrical conductivity of ZnO :F thin films..109 IV.1.2.2.5.Conclusion.........110 IV.2.References..............112 General Conclusion and prespectives............................115 |
| En ligne : | http://thesis.univ-biskra.dz/3847/1/Thesis%20Of%20Doctorate%20-%20Mohamed%20Othmane.pdf |
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