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Electrodeposition of Polyphasic [(ZnO)a(ZnO2)b(ZnS)c] Thin Films in DMSO Solution. Study of Their Morphological, Optic and Crystalline Porperties.
|Rodrigo Henríquez 1, Enrique Dalchiele 3, Humberto Gómez 1, Daniel Lincot 2, Paula Grez 1|
1. Pontificia Universidad Católica de Valparaíso (PUCV), Avda Brasil 2950, Valparaíso Chile, Valparaíso xxxx, Chile
In this work the structural and optic properties of the polyphasic [(ZnO)A(ZnO2)B(ZnS)C] thin films was studied. The synthesis of the films was performed by electrodeposition (ED) at controlled potential in dimethilsulfoxide (DMSO) solution. Compared with aqueous solution, the election of the organic solvent was done considering the wider potential window for electrochemical processes and the possibility to dissolve chalcogenide precursors. The cathodic potential applied to the working electrode allowed the electrochemical reduction of molecular oxygen (O2) and thiourea ((NH2)2CS) as source of sulfide ions, at 373 K according to the following reactions:
TU + 2 e– ® S2– + CN– + NH4+ (1)
O2 + e– ® O2– (2)
Which were analyzed by cyclic voltammetry. The films were formed on two different substrates; tin oxide fluorine doped glass (SnO2:F, FTO) and a mono-crystalline n – type InP substrate (1,0,0) and (1,1,1) with crystallographic plane in the phosphorous face. These deposits showed a particular morphology like honeycomb, which were observed by SEM. The morphology was independent of the electrodeposition potential employed. This morphology possesses a marked polycrystalline character, which was confirmed by the RHEED patterns. In these patterns, numerous rings could be observed and was assigned to the three phases present in the film. However, the presence of supplementary reflections (dots) in the patterns, confirm that ZnS phase (ZnS/InP mistmach –7%) showed an epitaxyal growth onto the mono-crystalline substrate.
The study of the transmission spectra of the deposits formed on FTO shows that the bang gap energy was 3.46 eV. Due to these results, it is possible to postulate that these phases can be employees as substitution of CdS as layer window in photovoltaic devices with Cu(In,Ga)Se2 (CIGS) as absorbent material.
Presentation: Poster at E-MRS Fall Meeting 2007, Symposium B, by Rodrigo Henríquez
See On-line Journal of E-MRS Fall Meeting 2007
Submitted: 2007-05-08 21:15 Revised: 2009-06-07 00:44