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HL: Halbleiterphysik

HL 10: Grenz- und Oberfl
ächen

HL 10.8: Talk

Monday, March 26, 2001, 17:15–17:30, S16

Characterization of the ZnSe/CuGaSe₂ Interface Using UHV Kelvin Probe Force Microscopy — •Thilo Glatzel¹, Sascha Sadewasser¹, Marin Rusu², Arnulf Jäger-Waldau¹, and Martha Ch. Lux-Steiner¹ — ¹Hahn-Meitner Institut, Berlin, GERMANY — ²State University of Moldova, Dept of Physics, Chisinau, MOLDOVA

To improve the efficiency of heterostructure solar cells based on chalcopyrite semiconductors a good understanding of the interface properties is crucial. By Kelvin Probe Force Microscopy it is possible to obtain laterally resolved images (resolution down to 20 nm) of the workfunction of semiconductor surfaces in addition and simultaneously to the topographical information usually obtained by non-contact AFM. ZnSe/CuGaSe₂ interfaces were prepared by growing CuGaSe₂ onto the (110) face of freshly cleaved ZnSe single crystals by different growth processes, i.e. CVD and MOCVD. On single CuGaSe₂ grains we observed different workfunction values for different facets. At the ZnSe/CuGaSe₂ interface, freshly cleaved in UHV, a smooth transition of the workfunction in a region of 2 µm at the interface was identified by studying the cross section of the heterojunction. Additionally a change in the crystalline structure of the ZnSe was observed. From the obtained workfunction data a schematic band diagram for the ZnSe/CuGaSe₂ heterostructure is proposed.