High quality factor whispering gallery modes from hexagonal GaN microrods

21.06.2013, 00:00

Newsletter 6

Self-assembled GaN microrods have been grown on sapphire substrates by metal-organic vapour phase epitaxy without the use of any catalyst and mask. Regular hexagonal shaped microrods formed, with diameters of 3-4 ?m, sharp edges and smooth sidewall facets. Micro-photoluminescence investigations showed the existence of whispering gallery modes (WGMs) superimposed on the characteristic yellow defect band of GaN. Many of the WGMs had a quality factor Q > 1000, demonstrating the high morphological and optical quality of such microcavities. Calculations are in agreement with the spectral positions of the WGMs. For a transverse magnetic (TM) WGM we observed a Q as high as 4177, which is comparable to the values reported by other groups in GaN microdisks fabricated using a more complicated procedure. We expect that lasing in the visible range can be achieved if these structures are surrounded with an optically active medium, e.g., incorporating InGaN quantum wells or dots. Furthermore, the microrods provide a basis for studying light-matter interactions at room temperature and may also serve as a highly sensitive molecule detectors.

Contact: christian.tessarek(at)mpl.mpg(dot)de
Group: Photonic Nanostructures (TDSU)
Reference: C. Tessarek et al., Opt. Express 21, 2733-2740 (2013).