GaN-based Nanorods for LEDs

• Applicant: Privatdozent Dr.-Ing. Hergo-Heinrich Wehmann
• Subject Area: Experimental Condensed Matter Physics
• Term: from 2004 to 2011
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 5429105

The goal of this project is to fabricate ZnO-based as well as GaN-based nanorods for a variety of different applications in optoelectronics, spintronics as well as sensorics. In particular, concepts for controlling size, composition and position of the nanorods are under investigation and will be explored further. MOVPE will be used as the growth technique of choice. Special efforts will be undertaken to grow ZnO nanorods on silicon, with the potential of combining ZnO based sensorics and magnetoelectronics with silicon microelectronics. The particular advantage of ZnO nanorods is that a surface oxidation is obviously not critical, unlike in other semiconductor systems. With its high exciton binding energy (in quantum wells up to 100 meV, larger than the LO phonon energy of 71 meV and much larger than the thermal energy at room temperature) as well as the potential for incorporating magnetic ions isoelectronically forming a transparent ferromagnetic semiconductor, ZnO based heterostructures are very interesting both in the field of magnetoelectronics and optoelectronics, as well as sensorics. In particular, magnetic ZnO (ZnCoO, ZnVO, ZnMnO) has been reported to be ferromagnetic with Curie temperatures above room temperature. Magnetic nanorods will therefore be explored as one possible system for magnetic data storage with an out of plane magnetisation. In addition, the possibility of combining ZnO nanorods with Bragg mirrors will be explored, in order to achieve a strong light-matter coupling, interesting for a possible realisation of a polariton laser. In summary, focus of the project will be the development of a technology to fabricate ZnO-based nanorods, to gain control on composition, size and position of these nanoobjects, and to apply this to prospective devices in the field of optoelectronics, magnetoelectronics and sensorics. Even though the focus of the work will be on ZnO, the possibility to achieve GaN-based nanorods will also be explored, which can be fabricated e. g. by the overgrowth of ZnO nanorods with GaN in the same MOCVD reactor.

• DFG Programme: Priority Programmes
• Subproject of: SPP 1165: Nanowires and Nanotubes: From Controlled Synthesis to Functions
• Participating Person: Professor Dr. Andreas Waag