Regensburg 2004 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe
HL: Halbleiterphysik
HL 24: Photovoltaik I
HL 24.3: Vortrag
Dienstag, 9. März 2004, 18:15–18:30, H15
Band alignment at the i-ZnO/CdS interface in Cu(In,Ga)(S,Se)2 thin film solar cells — •L. Weinhardt1, C. Heske1, E. Umbach1, S. Visbeck2, T.P. Niesen2, and F. Karg2 — 1Exp. Physik II, Universität Würzburg — 2Shell Solar GmbH, Munich
In solar cells based on Cu(In,Ga)(S,Se)2 (CIGSSe) one potential
target for further optimization of cell performance is the
commonly used ZnO window layer. Today, an n-ZnO/i-ZnO structure is
generally used, separated from the CIGSSe absorber by a CdS buffer
layer. Apart from important bulk parameters of the ZnO layer, such
as window transmission and resistivity, particularly the
properties of its interface to the CdS buffer layer represent a
crucial component for the optimization of solar cells. For a
further improvement of this interface a detailed understanding of
the chemical and electronic properties is needed. We have thus
investigated the ZnO/CdS interface using X-ray photoelectron
spectroscopy to probe its chemical properties, and we have used UV
and inverse photoemission for a direct determination of the band
gaps and band alignments at the heterojunction. The results will
be discussed in view of a level alignment model for the complete
CIGSSe thin film solar cell device, taking into account the
previously found electronic and chemical structure of the
CdS/CIG(S)Se interface [1,2] as well as new results for absorbers
with varied sulfur content at the surface.
[1] L. Weinhardt et al., Proc. 17th EPSEC Munich 2001, p. 1261.
[2] M. Morkel et al., Appl. Phys. Lett. 79 (2001) 4482.