Regensburg 2010 – scientific programme

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O: Fachverband Oberflächenphysik

O 86: Organic, electronics and photovoltaics

O 86.6: Talk

Friday, March 26, 2010, 12:30–12:45, H40

Band alignment studies of ZnO-ZnS-CIS interfaces — •Carsten Lehmann, Andreas Hofmann, Alexandra Dombrowa, and Christian Pettenkofer — Helmholz-Zentrum Berlin, Berlin, Deutschland

With respect to thin film solar cells based on CuInS₂ and ZnO ZnS is a promising alternative to CdS as buffer layer material [1,2]. A MOMBE process based on diethylzinc and water is investigated on CuInS₂(112) thin films. A ZnS buffer layer grows epitaxially using the surplus of sulfur in the eventually present CuS_x layer. A ZnO film grows on top of the .8 nm thick ZnS layer with its own lattice parameters in (0001) direction. Step-by-step analysis of this ZnO-ZnS-CIS interface yielded a band alignment favorable for photovoltaic applications [2]. We present in-situ preparation and step-by-step investigation on ZnO-ZnS-CIS interfaces with varying CIS substrates. CuInS₂(001) samples were prepared on GaAs(100) by gas source MBE (GSMBE) using TBDS as sulfur precursor. Sulfurization of CuIn films prepared by MBE and sputtering yielded polycrystalline CuInS₂ samples of 100nm up to 2.5µm thickness. The samples were investigated by XPS, UPS and LEED. We will discuss the interfaces with respect to the derived band aligments and their morphology. Furthermore we will compare the results to those of analogous experiments on CuInSe₂(112). [1] M. Bär, et. al., Journal of Applied Physics 99 (2006) [2] S. Andres, et. al., Thin Solid Films 518 (2009)

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