Regensburg 2004 – wissenschaftliches Programm

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DS: Dünne Schichten

DS 20: Dünne Schichten für die Photovoltaik II

DS 20.4: Vortrag

Donnerstag, 11. März 2004, 15:15–15:30, HS 32

Metal organic molecular beam epitaxy (MOMBE) of CuInS₂ on Si(111) — •Carsten Lehmann, Wolfram Calvet, and Christian Pettenkofer — Hahn-Meitner-Insititut, Glienicker Strasse 100, 14109 Berlin

The ternary compound semiconductor CuInS₂ with a direct band gap of 1.53 eV seems to be very promising as absorber material for thin film solar cells. We report on thin epitaxial CuInS₂ layers prepared on hydrogen terminated Si(111) by metal organic molecular beam epitaxy (MOMBE). The deposition steps are monitored in situ with photoelectron spectroscopy (PES) and low energy electron diffraction (LEED). Ex situ, x-ray diffraction (XRD) and secondary electron microscopy (SEM) complement the film analysis. The film growth is improved by additional ultraviolet (UV) light leading to epitaxial films showing ordered (1x1) LEED patterns of the surface. Additionally, the segregation of elemental In occurs in the In-rich regime of preparation. No carbon contamination is detected in the film indicating a clean reaction of the sulfur precursor. Further, the formation of Cu₂Si is observed at the interface during the nucleation phase. From SEM it can be deduced that this additional phase penetrates into the Si substrate forming extended hillocks. Obviously, the quality of the CuInS₂ films is sensitively influenced by the initial growth conditions.