Berlin 2008 – scientific programme

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O: Fachverband Oberflächenphysik

O 30: Phenomena at Semiconductor Surfaces

O 30.8: Talk

Tuesday, February 26, 2008, 13:45–14:00, MA 041

Investigation of crucial interfaces for III-V multi-junction solar cells — •Ulf Seidel, Henning Döscher, and Thomas Hannappel — Hahn-Meitner-Institut, Glienicker Str. 100, 14109 Berlin, Germany

Currently high efficiency III-V multi-junction solar cells are grown epitaxially on Ge(100)-substrates, which are simultaneously utilized for the low band gap subcell. Our concept is the replacement of Ge in these devices by a more efficient InGaAsP/InGaAs tandem solar cells integrated on Si(100) substrates. According structures contain many different layers of III-V semiconductors, which were prepared in this work via MOVPE. For the best performance of the solar cells sharp hetero-interfaces are necessary. Here, the investigation of two interfaces is presented in detail: (1) InGaAs/GaAsSb that is needed in the tunnel junction of our low band gap multi-junction solar cell and (2) Si/GaP that is needed for the epitaxy of our III-V solar cells on silicon(100) substrates instead of InP(100). Both interfaces were characterized in-situ during the MOVPE-growth with reflectance difference spectroscopy (RDS) and after a contamination free transfer in ultra high vacuum with X-ray photoelectron spectroscopy (XPS), low energy electron diffraction (LEED) and scanning tunnelling microscopy. Additionally AFM micrographs were recorded.