Scanning tunneling spectroscopy of quantum coherence phenomena due to atom-by-atom nanostructure assembly on semiconductor surfaces

• Applicant: Dr. Stefan Fölsch
• Subject Area: Experimental Condensed Matter Physics
• Term: from 2008 to 2011
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 94778613

The joint project will be made possible by combining the expertise of both research partners. The Japanese side (NTT Basic Research Laboratories (NTT)) has excellent expertise in the field of molecular beam epitaxy (MBE) of InAs and GaAs-based III-V compound semiconductor materials and their characterization by low-temperature scanning tunneling spectroscopy (STS). NTT operates one of the few facilities worldwide which combine MBE with in situ low-temperature scanning tunneling microscopy (LT-STM) capabilities. The German side (Paul Drude Institute (PDI)) has outstanding expertise in the field of atom manipulation by LT-STM and STS characterization of individual metal-on-metal nanostructures assembled one atom at a time.The goal is to push the frontiers forward to the atom-by-atom assembly of individual nanostructures on semiconductor surfaces by using single adatoms as building blocks. The targeted applicability of atom manipulation to semiconductors – in combination with the spectroscopic capabilities of LT-STM – will represent a major advance in the attempt to understand and control electron behavior in semiconductor nanostructures. This understanding is of crucial importance for future device functionality based on quantum structures on semiconductor platform. In a joint experiment, we recently succeeded in reversible atom manipulation and versatile nanostructure assembly on InAs substrates, allowing us to create and to modify nanostructure-confined electronic states in an atom-by-atom fashion. This achievement is – to our knowledge – a worldwide novelty in the field of semiconductor materials and will mark the starting point of the project. Up to now, there is no reported success in the characterization and control of semiconductor-based quantum coherence phenomena utilizing atom-by-atom-assembled nanostructures at surfaces. These facts indicate that our joint project will yield a pioneering contribution to nanometer-scale science and technology.

• DFG Programme: Research Grants
• International Connection: Japan
• Participating Person: Dr. Kiyoshi Kanisawa