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HL: Fachverband Halbleiterphysik

HL 16: III-V semiconductors II

HL 16.5: Vortrag

Dienstag, 24. März 2009, 10:30–10:45, POT 151

Optical characterisation of AlGaN/GaN MQW — •Christian Nenstiel¹, Ronny Kirste¹, Viola Küller², Frank Brunner², Arne Knauer², Markus Weyers², and Axel Hoffmann¹ — ¹Institut für Festkörperphysik, TU Berlin, Hardenbergstr. 36, 10623 Berlin — ²Ferdinand-Braun-Institut für Höchstfrequenztechnik (FBH) in Berlin, Germany

The direct transition energy of the ternary semiconductor AlGaN system can be adjusted between 6.2 eV (AlN) and 3.4 eV (GaN). The preferences of AlGaN/GaN multiple quantum wells (MQW) are the large bandgap, large longitudinal phonon energy, good carrier confinement and ultra fast carrier and intersubband relaxation. These properties make AlGaN/GaN and AlGaN/AlN MQWs a possible material for optoelectronic devices like ultra violet light emitting diodes, laser diodes or photodetectors. AlGaN MQWs were grown on [0001]-oriented sapphire substrates (c-plane) by metal organic vapour phase epitaxy at high temperatures around 1500^∘C. In this contribution we analyse Al₂₈Ga₇₂N:nid and Al₂₈Ga₇₂N:Si samples with super lattice structures consisting of 10 - 80 layers with 1 - 11nm thickness. The samples were investigated by Raman spectroscopy and temperature-dependent photoluminescence. The Raman spectra show a shift of the strain-sensitive E₂ (high) mode, which can be attributed to the doping of the sample. The temperature-dependent photoluminescence spectra demonstrate different exciton energies and defect luminescences of the samples. Thereby the strength of the defect luminescence depends on the structure and doping of the samples.