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Thin-film polycrystalline-Si solar cells on
have a large potential for cost reduction.
However, good electrical and crystal layer
properties are necessary to reach competitive energy conversion efficiencies.
The choice of the base substrate is crucial. Usual substrates are generally
quite rough and not transparent which presents a disadvantage for solar cell
processing.
Substrate
Roughness
The substrate roughness has a large effect
on all aspects of our pc-Si solar cell process. A smoother substrates lead to a
bigger grain size in the absorber layer and to an increase in generated voltage
and efficiency of the resulting solar cells.
Solar Cell
Efficiency
On the other hand, the efficiency of
hydrogenated amorphous silicon solar cells can be significantly improved when
enhancing the light absorption in the thin layers by introducing light
scattering at rough surfaces. Therefore it is important to investigate the
roughness of solar cell.
Figure 1. Polycrystalline-Si solar cell surface. Scan range 90ìm x 90ìm; Z
range 7.6ìm
AFM can provide precise, qualitative and
quantitative roughness measurements of surfaces. The image shows the topography
of the P-doped polycrystalline-Si layer of a solar
cell. |