| Titre : | Deposition and analysis of Zinc Oxide thin films elaborated using spray pyrolysis for photovoltaic applications |
| Auteurs : | Fouad Bouaichi, Auteur ; Abdallah Attaf, Directeur de thèse ; Hanane Saidi, 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, 2019 |
| Format : | 1 vol. (137 p.) / 30 cm |
| Langues: | Anglais |
| Mots-clés: | Spray pyrolyse,Couches minces de ZnO,Ultrasonique,Pneumatique,Molarité,ZnO: Al,ZnO: In,température de substrat,DRX,MEB,UV-Vis,propriétés électriques. |
| Résumé : |
Undoped and doped (by Al and In) ZnO thin films were deposited via two types of spray pyrolysis technique, ultrasonic and pneumatic onto glass substrates, to investigate the effect of several factors on the structural, optical and electrical properties of ZnO thin films. In the first part, we have deposited set samples of ZnO thin films using ultrasonic spray pyrolysis process with various start solution molarities for undoped ZnO and various doping concentrations for Al and In doped ZnO films. In the second, ZnO thin films were deposited using pneumatic spray pyrolysis process with two deferent spray pressure (1 and 1,5 bar) and various substrate temperatures for each pressure; also ZnO films with various aluminium doping rates were prepared. As well as, All the ZnO thin films were analyzed by assorted techniques X-ray diffraction, X-ray Dispersive Spectroscopy (EDS), SEM, UV-Vis, Hall Effect, four and two probes technique. This study allowed us to get ZnO thin films with very important structural, optical and electrical properties, which are very promising in photovoltaic applications. |
| Sommaire : |
Acknowledgements………………………….……………………………….……… List of Tables………………………….……………………………….…………….. List of figures………………………….……………………………….…………….. General Introduction………………………….……………………………….…… Chapter I: Review of the Zinc Oxide Thin Films Properties and Growth techniques. I.1. Introduction………………………………….………………………...…………… 5 I.2. Chapter Objectives……………………………..…………………………………... 5 I.3. Transparent conducting oxides………………………………………….………… 5 I.3.1. Definition…………………………………………………………….……...……… 5 I.3.2. TCOs in General………………………………………………………….………… 5 I.4. History of Zinc oxide (ZnO) research………………………...……….…………… 6 I.5. ZnO choice…………………………………………………………..……………... 7 I.6. Properties of Zinc Oxide………………………………………………...…….…… 8 I.6.1. Crystal Structure……………………………………………………………………. 8 I.6.2. Electronic band structure of ZnO…………………………………………………... 10 I.7. Doping of ZnO………………………………………………………..……………. 12 I.8. ZnO thin films applications………………………………………………………… 13 I.8.1. ZnO thin films for photovoltaics…………………………………………………… 14 I.9. Different growth techniques of ZnO…………………………………….…………. 15 I.9.1. Chemical Vapour Deposition……………………………………..…….………… 17 I.9.2. Physical Vapour Deposition……………………………...…………….………… 18 I.9.3. Radio frequency magnetron sputtering……………………………….………..…… 19 I.9.4. Laser Ablation……………………………………………………….……………… 20 I.9.5. Sol gel…………………………….………………………………….…………… 21 References……………………..…..……………………………………………...……… 24 Chapter II: Growth process and characterization devices for ZnO thin films II.1. Introduction……………………………………………………………….………. 28 II.2. Chapter Objectives……………………………………………………….……….. 28 II.3. Experimental technique………………………………………………..………….. 28 II.3.1. Spray pyrolysis technique………………………………………………………….. 28 II.3.1.1. General Description of Spray pyrolysis………………………………………..… 28 II.3.1.2. Decomposition of precursor…………………………………………………… 31 II.4. Spray Apparatus…………………………………………………..…..…………… 31 II.4.1. Specifications………………………………………………………...…..……… 31 II.4.2. Equipment components………………………………………………..……...…… 32 II.4.2.1. Spray pneumatic components………………………………………..……..…… 34 II.4.2.1.1. Air compressor…………………………………………..………..…………… 34 II.4.2.1.2. Syringe pump (Flow rate controller) ………………………………..………… 34 II.4.2.2. Spray ultrasonic components……………………...…………………..………… 34 II.4.2.2.1. Ultrasonic generator…………………………………………..…..…………… 34 II.4.2.2.2. Solution flow rate controller……………………………….…………...……… 34 II.4.2.3. Common components……………………………………..……………..……… 34 II.4.2.3.1. Scanning system (XY position controller) …………………………..…..…… 34 II.4.2.3.2. Hot plate……………………………………………………………..………… 34 II.4.2.4. Holmac’s software………………………………………………...…..………… 34 II.5. Growth process details…………………………………………………….……… 35 II.5.1. Substrate preparation………………………………………………..…..………… 35 II.5.1.1. Substrate selection………………………………………………….....………… 35 II.5.1.2. Substrate cleaning………………………………………………….....………… 35 II.5.2. Preparation of precursor solution………………………………………..………… 36 II.5.3. Films deposition…………………………………………………………..……….. 37 II.6. Characterization Methods of Thin Films………………………………………… 40 II.6.1. X-ray Diffraction Technique……………………………………..……..………… 40 II.6.1.1. The texture coefficient……………………………………….………..………… 42 II.6.1.2. Grain size determination…………………………………..……………..……… 43 II.6.1.3. Stress determination…………………………….……………………..………… 43 II.6.2. Scanning electron microscopy (SEM) ……………………………………..……… 44 II.6.3. Film thickness calculation……………………………………………….……… 46 II.6.3.1. Scanning electron microscopy…………………………………………………… 46 II.6.3.2. UV-Visible Spectrophotometry…………………………..……………………… 47 II.6.3.3. Weight difference method……………………………………………..………… 47 II.6.4. HebalOptics software……………………………………….…………………… 48 II.6.5. Optical characterization………………………………………….………………… 49 II.6.5.1. UV-Vis spectroscopy…………………………………………………..………… 49 II.6.5.2. The absorption coefficient………………………………………..……………… 51 II.6.5.3. Refractive index and extinction coefficient calculation………………………… 51 II.6.5.4. Band gap energy………………………………..………………………..……… 51 II.6.5.5. Urbach energy……………………………………..………………..…………… 52 II.6.6. Electrical resistivity measurement………………………………….……………… 53 II.6.6.1. Four probes method…………………………………………………...….……… 53 II.6.6.2. Electrical resistivity calculation………………………………………….……… 54 II.6.7.1. Hall effect measurement………………………………………….…..………… 55 References……………………...……………………………………….………….....… 58 Chapter III: Results and Discussion - Ultrasonic Spray III.1. Introduction…………………………………………….……………………...….. 61 III.2. Chapter Objectives…………………………………..………………..………….. 61 III.3.Effect of Molarity…………………………………..……………..……………… 61 III.3.1. Structural Characterization………………….……………………………………. 61 III.3.1.1. The texture coefficient…………………………………………….…………… 63 III.3.1.2. Grain size determination…………………………………………….…………. 64 III.3.1.3. Stress variation of ZnO thin films……………………………………………… 65 III.3.1.4. Film thickness calculation of ZnO thin films……………………….….….…… 66 III.3.1.5. Surface Morphology (Scanning electron microscopy) ………………………… 67 III.3.2. Optical characterization (UV-Vis) ………………………………………….…… 67 II.3.2.1. Band gap energy and urbach energy……………………………………………... 68 III.3.3. Electrical characterization…………………………….…..……………………… 70 III.3.3.1. Resistivity of Zinc Oxide Films……………………………..……..…………… 70 III.3.4. In summary ………………………………………………………………………. 70 III.4. Effect of dopants………………………..………………………..………………… 71 III.4.1. Effect of aluminium doping…………………………………..…...…………… 71 III.4.1.1. Structural Characterization…………………………….………..……………… 71 III.4.1.1.1.The texture coefficient………………………………………………………… 73 III.4.1.1.2. Grain size variation of Al-doped ZnO thin films…………………..………… 75 III.4.1.1.3. Stress variation of Al-doped ZnO thin films……………………….………… 77 III.4.1.1.4. Film thickness calculation of Al-doped ZnO thin films…………..….……… 78 III.4.1.1.5. Surface Morphology (Scanning electron microscopy) ……………………… 79 III.4.1.1.6. The Energy X-ray Dispersive Spectroscopy (EDS)…………………………. 81 III.4.1.2. Optical characterization (UV-Vis) …………………...……………….……….. 82 III.4.1.2.1. Band gap energy Urbach energy………………………………….…..……… 83 III.4.1.3. Electrical characterization……………………………………...…………….… 85 III.4.1.3.1. Resistivity of Al-doped ZnO thin Films…………………………...………..… 85 III.4.1.4. In summary …………………………………………………………………….. 87 III.4.2.Effect of Indium doping…………………………….…...………………….…… 88 III.4.2.1.Structural Characterization……………………………….……………………… 88 III.4.2.1.1.The texture coefficient…………………………….………………..………… 90 III.4.2.1.2.Grain size of Indium ZnO thin films……………………………..…….……… 91 III.4.2.1.3.Stress variation of In-doped ZnO thin films ……………………..……… 92 III.4.2.1.4.Film thickness calculation of In-doped ZnO thin films…………….………… 93 III.4.2.2.Optical characterization (UV-Vis) …………………………..….……………… 94 III.4.2.2.1.Band gap energy and urbach energy………………………………………… 95 III.4.2.3.Electrical characterization……………………………………………………… 97 III.4.2.3.1.Electrical conductivity of In-doped ZnO thin films…………………………… 97 References……………………….……………………………….………………….....… 99 Chapter IV: Results and Discussion - Pneumatic Spray IV.1. Introduction…………………………………………….……………………...….. 104 IV.2. Chapter Objectives…………………………………..………………………..….. 104 IV.3.Effect of Substrate temperature………………………………...………..……… 104 IV.3.1. Part one: Substrate temperature – Spray pressure: 1,5 bar ………………… 104 IV.3.1.1.Structural Characterization………………………………………..…………… 104 IV.3.1.1.1.Grains size of undoped ZnO thin films…………………………..…..……… 106 IV.3.1.1.2.Stress variation of undoped ZnO thin films……………………..…………… 107 IV.3.1.1.3.Film thickness of undoped ZnO thin films …………………..….…………… 109 IV.3.1.2.Optical characterization (UV-Vis) …………………………………………… 110 IV.3.1.2.1.Band gap energy and Urbach energy of undoped ZnO…...………………… 111 IV.3.1.3.Electrical characterization…………………………………………………….. 112 IV.3.1.3.1.Resistivity of Zinc Oxide Films………………………………………………. 112 IV.3.2.Part two: Substrate temperature – Spray pressure: 1 bar………....…..….… 113 IV.3.2.1.Structural Characterization…………………..………………………………… 114 IV.3.2.1.1.Grain size calculation of undoped ZnO thin films…………………………… 115 IV.3.2.1.2.Stress variation of undoped ZnO thin films…………………………..……… 116 IV.3.2.1.3.Film thickness variation of undoped ZnO thin films………………….……… 118 IV.3.2.2.Optical characterization (UV-Vis) ………………...…………………………… 118 IV.3.2.2.1.Band gap energy and Urbach energy ……………………...…………….…… 119 IV.3.2.3.Electrical characterization……………………………………………………… 121 IV.3.2.3.1.Resistivity of Zinc Oxide thin films………………..………………………… 121 III.3.2.4. In summary ……………………………………………………………………. 122 IV.4.Effect of Aluminium doping…………...……………..………………...………… 123 IV.4.1.Structural Characterization……………………………….……….……………… 123 IV.4.1.1.Grain size calculation of Al-doped ZnO thin films………………….………… 126 IV.4.1.2.Stress variation of Al-doped ZnO thin films………….…………………...…… 127 IV.4.2.1.3. Film thickness variation of Al-doped ZnO thin films……………..………… 128 IV.4.2.Optical characterization (UV-Vis) …………….…………………………….…… 129 IV.4.2.1.Band gap energy and Urbach energy of Al-doped ZnO thin films………..…… 130 IV.4.3.Electrical characterization………………………………………………….……… 132 IV.4.3.1.Electrical conductivity of Al-doped ZnO thin films ……...…………………… 132 III.4.4. In summary ……………………………………………………………………… 133 References……………………...……………………………………………………....... 134 General Conclusion………..………………………….…………………………...... 136 Abstract ………..………………………………..……….…………………………...... 138 |
| En ligne : | http://thesis.univ-biskra.dz/id/eprint/4533 |
Disponibilité (1)
| Cote | Support | Localisation | Statut |
|---|---|---|---|
| TPHY/79 | Théses de doctorat | bibliothèque sciences exactes | Consultable |
