| Titre : | Elaboration and characterization of chalcogenide thin films by chemical bath deposition technique |
| Auteurs : | Azzeddinne Beggas, 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. (130 p.) / 30 cm |
| Langues: | Anglais |
| Mots-clés: | Thin films,Chemical synthesis,FTIR,Optical properties,Structural properties,Chemical bath deposition. |
| Résumé : |
Chemical bath deposition, which is a very attractive method, used to produce thin films for polycrystalline solar cells such as CdS and PbS. This work was based on this method. Our objective is to provide a comprehensive study on the efiect of the deposition parameters on the structural and optical properties of CdS and PbS thin films and to monitor all reactions steps leading to CdS thin films formation.For the CdS thin films the bath solution is a mixture of cadmium carbonateCdCO3 and thiourea as source of cadmium and sulphur respectively, ammonia was used as complexing agent. In this study, two sets of samples were prepared, in eachset only one parameter is varied while the rest of parameters were fixed. In the first set, a few drops of sulphuric acid were added while in the second more of sulphuric acid were added. In order to investigate the deposition time. For both sets, films were deposited for difierent durations ranging from 30 to 90 min at bath temperature 55fiC. X-raydifiraction, UVvisible spectrophotometry and Fourier transforminfrared techniques were used to investigate CdS thin films and the difierent steps of reactions leading to CdS product. For the first set, the growth of films occursby the mechanism ion-by-ion with low deposition rate. Hexagonal CdS thin films were obtained with (002) preferred orientation and having average crystallite size in the range of 14.3 to 30.4 nm. All the films exhibit a high transmittance in the visible range; it is in order of 70 to 92% , the values of the optical gap are between 2.42 and 2.58 eV, this according to deposition time. Studies of difierent solutionsand steps leading to the formation of CdS products were carried. The formation mechanism of CdS thin films was proposed based on FTIR results. For the second set. The obtained CdS films in this case have cubic structure with a preferential 130 orientation along the axis (111) and crystallite size between 24.4 and 38.9 nm. The transmittance of the films was found to be in order of 40 to 80%, the values of the optical band gap increases with deposition times from 2.19 to 2.35 ev. In this work, PbS thin films were prepared for difierent deposition times ranging from 30 to 90 min and difierent lead nitrate molar concentrations (0.01, 0.05, 0.075 and 0.1) mol=l at a bath temperature of 55fiC, using thiourea as source of S2 |
| Sommaire : |
DEDICACE : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : x ACKNOWLEDGMENTS : : : : : : : : : : : : : : : : : : : : : : : : : : xi INTRODUCTION : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 1 CHAPTER 1: LITTERATURE REVIEW : : : : : : : : : : : : : : : 6 1.1 Semiconductors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 1.2 Survey on cadmium sulphide thin films: . . . . . . . . . . . . . . . . 7 1.2.1 Structural properties . . . . . . . . . . . . . . . . . . . . . . 7 1.2.2 Optical Properties . . . . . . . . . . . . . . . . . . . . . . . 16 1.2.3 Compositional Analysis . . . . . . . . . . . . . . . . . . . . . 20 1.3 Survey on lead sulphide thin films: . . . . . . . . . . . . . . . . . . 21 1.3.1 Structural properties . . . . . . . . . . . . . . . . . . . . . . 21 1.3.2 Optical properties . . . . . . . . . . . . . . . . . . . . . . . . 25 CHAPTER 2: FILMS DEPOSITION AND CHARACTERIZATION 38 2.1 Thin film materials . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 2.2 Thin deposition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 2.3 Chemical bath deposition technique . . . . . . . . . . . . . . . . . . 40 2.4 Principle of (CBD) technique . . . . . . . . . . . . . . . . . . . . . 41 2.5 Mechanism of the (CBD) process . . . . . . . . . . . . . . . . . . . 42 2.5.1 The simple ion-by-ion mechanism . . . . . . . . . . . . . . . 43 2.5.2 The simple cluster by cluster (Hydroxide cluster) mechanism 44 ii 2.5.3 The complex decomposition ion-by-ion mechanism . . . . . . 46 2.5.4 The complex decomposition cluster mechanism . . . . . . . 47 2.6 Deposition kinetics . . . . . . . . . . . . . . . . . . . . . . . . . . . 47 2.7 Thin films preparation . . . . . . . . . . . . . . . . . . . . . . . . . 49 2.7.1 Elaboration of PbS and CdS thin films . . . . . . . . . . . . 49 2.7.2 Growth of CdS thin films . . . . . . . . . . . . . . . . . . . 49 2.7.3 Growth of PbS thin films . . . . . . . . . . . . . . . . . . . 51 2.8 Films Characterization . . . . . . . . . . . . . . . . . . . . . . . . . 53 2.8.1 Structural properties . . . . . . . . . . . . . . . . . . . . . . 53 2.8.2 Optical Properties . . . . . . . . . . . . . . . . . . . . . . . 58 2.8.3 Fourier transform infrared spectroscopy (FTIR) . . . . . . . 61 CHAPTER 3: CHARACTERIZATION OF CDS THIN FILMS : 65 3.1 Evolution of properties of CdS thin films . . . . . . . . . . . . . . . 65 3.1.1 Film Thickness and Growth Kinetics . . . . . . . . . . . . . 66 3.1.2 Results of the XRD measurements . . . . . . . . . . . . . . 69 3.1.3 Optical properties of the CdS thin films . . . . . . . . . . . 76 3.2 Chemical reactions and solution preparation . . . . . . . . . . . . . 79 3.2.1 FTIR spectrum of cadmium carbonates (CdCO3) . . . . . . 80 3.2.2 FTIR spectrum of calcined products from A and B . . . . . 80 3.2.3 Efiect of ammonia on B solution . . . . . . . . . . . . . . . . 82 3.3 The total elimination efiect of CdCO3 on the properties of the CBD CdS thin films . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85 3.3.1 Film Thickness and Growth Kinetics . . . . . . . . . . . . . 85 3.3.2 Results of the XRD measurements . . . . . . . . . . . . . . 86 3.3.3 Optical properties of the CdS thin films . . . . . . . . . . . 91 CHAPTER 4: CHARACTERIZATION OF PBS THIN FILMS : 98 4.1 Efiect of deposition time . . . . . . . . . . . . . . . . . . . . . . . . 98 4.1.1 Evolution of crystal structure . . . . . . . . . . . . . . . . . 98 iii 4.1.2 Optical properties of the PbS thin films . . . . . . . . . . . . 105 4.2 Efiect of lead nitrate concentration . . . . . . . . . . . . . . . . . . 111 4.2.1 Evolution of crystal structure . . . . . . . . . . . . . . . . . 111 4.2.2 Optical properties of the PbS thin films . . . . . . . . . . . 117 4.2.3 FT-IR measurements . . . . . . . . . . . . . . . . . . . . . . 122 CONCLUSIONS AND OUTLOOK : : : : : : : : : : : : : : : : : : : : 126 ABSTRACT : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 129 |
| En ligne : | http://thesis.univ-biskra.dz/3825/1/These.pdf |
Disponibilité (1)
| Cote | Support | Localisation | Statut |
|---|---|---|---|
| TPHY/60 | Théses de doctorat | bibliothèque sciences exactes | Consultable |
