Dresden 2003 – scientific programme

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HL: Halbleiterphysik

HL 30: Photovoltaik

HL 30.15: Talk

Wednesday, March 26, 2003, 18:00–18:15, BEY/81

Band structure of CuI/CuInS2 heterointerface — •Igor Konovalov and Rüdiger Szargan — Wilhelm-Ostwald-Institut für physikalische und theoretische Chemie, Universität Leipzig, Linnéstr. 2, 04103 Leipzig

The band offset at an interface between two different semiconductors has a significant influence on the electrical properties of the correspondent semiconductor device. For example, chalcopyrite solar cells based on p-type CuInS2 semiconductor are far away today from reaching the expected efficiency due to a non-optimal conduction band alignment with a cliff at the interface to transparent semiconductors of n-type. We have investigated the valence band alignment between single crystal CuInS2 and a typical transparent p-type semiconductor CuI using X-ray photoelectron spectroscopy. It was found that the valence band offset at this interface is preferentially of the spike type and it is smaller than 0,2 eV. This result can be explained from the point of view of the doping pinning rule. The position of the valence band maximum has been determined from the X-ray photoelectron spectra under assumption of the parabolic distribution of the density of states near the valence band maximum and assuming the normally distributed instrument response. The structure of the valence band of in-situ deposited CuI films has been also investigated.