Study of the properties of heterostructures based on semiconductor metal oxides obtained by electrochemical deposition.
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The main goal of this thesis was to improve the performance of the electrodeposited Cu2O/ZnO heterojunction device by applying many strategies, such as the insertion of ZnO buffer layer, adjusting the pH of Cu2O deposition bath and engineering a back surface field architecture. At first, we deposited a p-Cu2O layer on n-ZnO (or AZO) layer by two steps electrodeposition. The properties of Cu2O/ZnO and Cu2O/Al:ZnO heterojunctions were investigated and we confirmed a good performance for Cu2O/ZnO device. To improve the performance for of this latter we deposited Cu2O/ZnO/Al:ZnO device by inserting ZnO layer, with different thickness, between Al: ZnO and Cu2O to enhance the mismatch and reduce the band offset. The device with 200nm ZnO show improvement of the performance compared to Cu2O/ZnO and Cu2O/Al: ZnO. Then, we improved the quality of Cu2O by increasing the deposition pH values and used it as an absorber layer. The Cu2O/ZnO heterojunction with 500 nm Cu2O deposited at pH 12 shows the best performance due to the low valence band offset of 1.8 eV. Finally, we fabrication Cu2O+/Cu2O/ZnO to enhance the light absorbance and the carrier collection length by the creation of back surface field devices. The 150 nm Cu2O+/300 nm Cu2O/ZnO heterojunction shows the best performance due to the low band valence offset (∆Ev) between 150 nm Cu2O+/300 nm Cu2O structure and ZnO layer.
- Doctorat (Chimie)