Abstract:
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.
