Defects, chemistry and ordering in nitride nanostructures

• Applicant: Professor Dr. Andreas Rosenauer, since 11/2007
• Subject Area: Theoretical Condensed Matter Physics
• Term: from 2003 to 2012
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 5470211

The proposed project aims for a thorough understanding of defect formation mechanisms in metal organic vapor phase epitaxy and molecular beam epitaxy grown group III nitride based heterostructures used for the realization of light emitters in the blue spectral region. In conjunction with transmission electron microscopy, which provides information about extended defects formed at interfaces as well as due to the insertion of impurity atoms for either doping purposes or to realize quantum dot layers, the x-ray standing wave technique will be utilized to determine the bonding structure of dopants at the surface and inside the bulk of the film. The XSW measurements will be performed together with density functional theory calculations, which are part of project III-1 to accomplish a detailed picture of the insertion of impurity atoms into GaN. Combining XSW with TEM gives unique possibilities to join detailed knowledge of the impact of impurity atom insertion into the lattice with a comprehensive investigation of the structural defects formed during growth. These investigations will focus on Mg-doped and Si-doped GaN as well as on the role of these dopants in the formation of stable facets in GaN films grown in the framework of project I-1. In conjunction with project II-1 the influence of impurities on the growth mode will be addressed. The results gained from the work proposed here will be of great value for optimizing the growth conditions for quantum dot laser structures and will provide important information for the understanding of surface modifications and the interaction of extended defects with the doping elements.

• DFG Programme: Research Units
• Subproject of: FOR 506: Physics of nitride-based, nanostructured, light-emitting devices
• Participating Person: Privatdozent Dr. Thomas Schmidt
• Ehemaliger Antragsteller: Dr. Roland Kröger, from 9/2007 until 11/2007