Dresden 2009 – wissenschaftliches Programm
HL 17.1: Vortrag
Dienstag, 24. März 2009, 10:00–10:15, BEY 154
Growth and Optical Properties of GaN Nanodisks in GaN/AlGaN Nanowires — •Florian Furtmayr1, Christoph Stark1, Martin Stutzmann1, Sònia Conesa-Boj2, Francesca Peiro2, Jordi Arbiol2, Joan Ramon Morante2, and Martin Eickhoff1,3 — 1Walter Schottky Institut, Technische Universität München, 85748 Garching — 2EME/CeRMAE/IN2UB, Dept. d’Electronica, Universitat de Barcelona, E-08028 Barcelona, Spain — 3I. Physikalisches Institut, Justus-Liebig-Universität, 35392 Giessen
We report on the self-assembled growth of GaN/AlGaN and GaN/AlN nanowires with embedded GaN nanodisks (NDs) by plasma assisted molecular beam epitaxy (PAMBE) on Si(111). GaN multi quantum wells with different thicknesses were formed between barriers of AlN or AlxGax−1N in different compositions. The samples were analyzed by high resolution transmission electron microscopy (HRTEM) and photoluminescence (PL). The PL emission energy of the NDs at 3.53 eV to 3.70 eV can be controlled by the variation of the Al-content in the barrier. Its intensity exceeds that of the GaN base of the NW (3.40 eV - 3.47 eV) by about a factor of ten. The FWHM increases with the Al-content and varies between 21 meV and 70 meV at 4K. Due to the presence of polarization fields, the emission energies show a red shift, which increases with increasing well-thickness. HRTEM analysis reveals well defined flat GaN NDs with sharp interfaces. Whereas the radial growth rate of the GaN region is almost zero, it is 11% of the axial growth for the AlN region, leading to the formation of an AlN shell around the NW.