Electrically stimulated coupling of nanostructures to wide bandgap semiconductors

• Applicant: Dr.-Ing. Andrej Denisenko
• Subject Area: Condensed Matter Physics
• Term: from 2004 to 2010
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 5429297

In this investigation we propose to reduce this constraint by using a novel technique, which involves coupling the already grown and processed nanowires and nanotubes of various types to the structured surfaces of wide bandgap semiconductors, such as diamond and GaN. The choice of the wide bandgap semiconductors is specified by the their high chemical resistance, large potential window for water stability, and by the technologically controlled electrical and electrochemical properties, which range from highly insulating and chemically inert to highly conductive and electrochemically active depending on the surface processing. The nanowelding process involves two steps, namely: (i) electrostatic separation of the nanowires suspended in a liquid solution at the substrate surface and, (ii) subsequent bonding of the located nanostructures to the pre-defined conductive spots by applying defined electrical pulses. The proposed project will focus on two main items: (i) evaluation of the electrically stimulated coupling technique for the diamond and GaN substrates ; and (ii) fabrication of the sensor device structures to study the performance of the immobilized nanostructures. The first part of the project will be focused on the principle aspects of the coupling technique including: - investigation of nanowire-liquid interface charges, including the effect of the catalytic precursor and surface pretreatment on the surface dipole, used for the local separation and transport of the nanowires ; - methods to form the contacting sites on the substrate surfaces including the creation of local defects by irradiation damage, lithographical or AFM-assisted patterning, for example by using graphitic point defects at the grain boundaries of nanocrystalline CVD films; - optimization of the electrically stimulated coupling process including the effect of the liquid solution and bias regimes on the local discharge phenomena; studying the stability of the immobilized structures. In the second part of the project those results will be used in the sensor fabrication technology.

• DFG Programme: Priority Programmes
• Subproject of: SPP 1165: Nanowires and Nanotubes: From Controlled Synthesis to Functions
• Participating Person: Professor Dr.-Ing. Erhard Kohn