Speaker: Marek Szymonski, Jagiellonian University, Krakow, Poland
Date & Time: May 4, 2006 - 12:00pm
Location: Chemistry 260, 12 Noon
Metal Nanostructures Assembled at Semiconductor Surfaces Studied with High Resolution Scanning Probes
Laboratory for Surface Modification
Jagiellonian University, Krakow, Poland
Chemistry 260, 12 Noon
Dynamic Force Microscopy (DFM), Kelvin Probe Force Microscopy (KPFM) and Scanning Tunnelling Microscopy/Spectroscopy (STM/STS) have been used to study epitaxial nanostructures formed as a result of sub-monolayer deposition of silver and gold on clean reconstructed InSb, InAs and Ge surfaces. It has been found that both topography and composition of the structures are strongly dependent on the substrate temperature during evaporation. In the particular case of Au deposited on c (8x2) InSb(001) surface at 300 K, the nanostructures have predominantly the form of rectangular islands with edges oriented along <110> and <1-10> directions. Increasing the substrate temperature up to 600 K during deposition results in formation of narrow, long structures (nanowires) with an average length of 800 nm. The nanowires are created along troughs of the reconstructed InSb (001) surface. High resolution KPFM and STS measurements indicated that nanowires of different heights could have different chemical composition and electronic structure. For comparison, the structures assembled by silver deposition on the same substrates have been investigated with various SPM probes. It was found that topographies and composition of Ag-based nanostructures are different from the gold ones.