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HL: Fachverband Halbleiterphysik

HL 50: HL Poster IV

HL 50.54: Poster

Donnerstag, 15. März 2018, 19:00–21:00, Poster B

KPFM under local illumination - direct observation of local band bending in contacted nanostructures — •Jan Siebels, Andreas Kolditz, Dino Behn, Tobias Kipp, and Alf Mews — Institut für Physikalische Chemie, Universität Hamburg, Grindelallee 117, 20146 Hamburg

The understanding and control of charge transfer processes within semiconductor materials and at interfaces is crucial for the design of semiconductor devices such as, e.g., solar cells, photodetectors, and gas sensors. Here, we demonstrate the power of Kelvin probe force microscopy with simultaneous, localized illumination of a nanostructure device by focused laser light. A combination of this technique with scanning photocurrent measurements allows the exploration of the mutual interaction between local charge carrier generation and band profiles. The nanostructure devices under investigation are Pt contacted (i) CdS nanowires and (ii) SnS nanosheets. For (i), the combined measurements show that local photocurrents can be explained by a strong dependence of the surface potential on the position of illumination while, for (ii), the occurrence of zero-bias photocurrent can directly be attributed to changes of the band bending due to the optically generated charge carriers.