Study of the surface properties of ZnO nanocolumns used for thin-film solar cells.
Densely packed ZnO nanocolumns (NCs), perpendicularly oriented to the fused-silica substrates were directly grown under hydrothermal conditions at 90 °C, with a growth rate of around 0.2 μm/h. The morphology of the nanostructures was visualized and analyzed by scanning electron microscopy (SEM). The surface properties of ZnO NCs and the binding state of present elements were investigated before and after different plasma treatments, typically used in plasma-enhanced CVD solar cell deposition processes, by X-ray photoelectron spectroscopy (XPS). Photothermal deflection spectroscopy (PDS) was used to investigate the optical and photoelectrical characteristics of the ZnO NCs, and the changes induced to the absorptance by the plasma treatments. A strong impact of hydrogen plasma treatment on the free-carrier and defect absorption of ZnO NCs has been directly detected in the PDS spectra. Although oxygen plasma treatment was proven to be more efficient in the surface activation of the ZnO NC, the PDS analysis showed that the plasma treatment left the optical and photoelectrical features of the ZnO NCs intact. Thus, it was proven that the selected oxygen plasma treatment can be of great benefit for the development of thin film solar cells based on ZnO NCs.
Institute of Physics AS CR v.v.i., Cukrovarnicka 10, 162 53 Prague, Czech Republic.
Neda
N
Neykova
Institute of Physics AS CR v.v.i., Cukrovarnicka 10, 162 53 Prague, Czech Republic.
Jiri
J
Stuchlik
Institute of Physics AS CR v.v.i., Cukrovarnicka 10, 162 53 Prague, Czech Republic.
Karel
K
Hruska
Institute of Physics AS CR v.v.i., Cukrovarnicka 10, 162 53 Prague, Czech Republic.
Ales
A
Poruba
Institute of Physics AS CR v.v.i., Cukrovarnicka 10, 162 53 Prague, Czech Republic.
Zdenek
Z
Remes
Institute of Macromolecular Chemistry AS CR v.v.i., Heyrovsky sq. 2, 162 06 Prague, Czech Republic.
Ognen
O
Pop-Georgievski
3-dimensional solar cells; X-ray photoelectron spectroscopy; ZnO nanocolumns; hydrothermal growth; optical spectroscopy; photothermal deflection spectroscopy; plasma treatment