Feb 24, 2009
Novel self-organized GaN nanorods
The Institute of Solid State Physics (IFP) at the University of Bremen is investigating different approaches to realizing high-power light emitting devices as well as single photon emitters. At first sight, these goals seem to be contradictory, but with the development of high quality, self-organized and catalyst-free grown gallium nitride nanorods both are realistic aims within the next years.
The nanorods were grown in the Semiconductor Epitaxy Group by using the advantages of both a metal-organic vapour-phase epitaxy system and a molecular beam epitaxy reactor on r-plane sapphire substrates. No catalysts or masks were necessary to obtain nanocolumns with outstanding crystalline and optical quality.
Depending on the growth conditions, it was possible to vary the density of the columns over two orders of magnitude. The optical quality and the low impurity-level were proven by microphotoluminescence measurements performed by the Semiconductor Optics Group at the IFP. The exciton-related emission shows linewidths that are unmatched for the growth of gallium nitride nanocolumns. To further confirm the high structural quality of the rods, transmission electron microscopy investigations (Electron Microscopy Group) and synchrotron radiation studies (Semiconductor Surface Group) are on the way.
The next steps are the realization of heterostructures (for example, alternating AlN/GaN layers or InGaN quantum wells) to create LED structures as well as the integration of a single quantum dot into such a nanocolumn to fabricate a single-photon emitter.
The researchers presented their work in Nanotechnology.
About the author
Timo Aschenbrenner is a PhD student in the Semiconductor Epitaxy group of Prof. Hommel at the Institute of Solid State Physics, University of Bremen, Germany. He is currently writing his thesis on a relatively diversified subject area centred around the epitaxial growth of group-III nitrides. Among his topics is the realization of quantum-dot-based laser diodes, the improvement of AlInN/GaN DBRs and finally the investigation of the above mentioned GaN nanorods. The financial support by the German Research Society (DFG) is acknowledged.