Optoelectronic Nanocharacterization
Scanning Probe - Group

Abstract

For the characterization of semiconductor surfaces and interfaces on a nanometer scale new spectroscopic techniques based on scanning probe microscopy are developed. Especially the Kelvin probe force microscopy (KPFM) is a very powerful tool to measure electrostatic forces and to obtain contact potential (CP) images with a high lateral resolution by non-contact (NC) atomic force microscopy (AFM).

So far, most of these experiments where performed in air. However, the quantitative determination of the CP requires ultrahigh vacuum (UHV) conditions. Therefore, we extended a commercial AFM (Omicron UHV-STM/AFM) for KPFM measurements in UHV. A PVD-preparation chamber is used for the growth of CuGaSe₂ and CdS films by evaporating the source materials under UHV conditions. Electronic and structural surface properties on atomic scale can be analyzed by a variable temperature STM (Omicron).