Dresden 2009 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 41: GaN: preparation and characterization II
HL 41.7: Vortrag
Donnerstag, 26. März 2009, 11:15–11:30, BEY 154
Optical properties of GaN nanorods grown catalyst- and mask-free on r-plane sapphire — •Joachim Kalden, Kathrin Sebald, Moritz Seyfried, Tobias Voss, Jürgen Gutowski, Timo Aschenbrenner, Gerd Kunert, Carsten Kruse, Stefan Figge, and Detlef Hommel — Institute of Solid State Physics, University of Bremen, P.O. Box 330 440, D-28334 Bremen, Germany
In the UV spectral region GaN is an up-and-coming material system for the realization of nanostructures with high crystalline quality. So far, such nanorods have been realized by either applying a mask or using a catalyst. Both approaches lead to an unintentional doping and the creation of deep centers, the latter one reducing the efficiency of the near-band edge emission. We present GaN nanorods which were grown catalyst- and mask-free in two steps. After nitridation via metal-organic vapor phase epitaxy the nanorod growth is realized via molecular beam epitaxy. These nanorods have brilliant optical properties. Microphotoluminescence measurements are performed at temperatures between 4 and 300 K. The excitonic emission band reveals several distinct lines which can be attributed to donor-bound (D0X) and acceptor-bound (A0X) excitons, respectively. The full width at half maximum (FWHM) of the D0X emission is 1.2 meV, proving the high crystalline quality. Furthermore, the free exciton is visible as a shoulder already at 4 K, while no yellow defect-related luminescence occurs. Microphotoluminescence experiments on single nanorods reveal strong luminescence intensity up to room temperature.