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HL: Fachverband Halbleiterphysik

HL 17: Quantum wires: Optical and transport properties

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 Eickhoff^1,3 — 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 Al_xGa_x−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.