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HL: Fachverband Halbleiterphysik

HL 46: Nitrides: mostly structural characterization

HL 46.4: Vortrag

Dienstag, 1. April 2014, 12:30–12:45, POT 051

Structural and optical properties of MBE grown asymmetric cubic AlGaN/GaN double quantum well structures — •Tobias Wecker¹, Florian Hörich², Martin Feneberg², Rüdiger Goldhahn², Dirk Reuter¹, and Donat J. As¹ — ¹University of Paderborn, Germany — ²Otto-von-Guericke University, Magdeburg

Asymmetric double quantum wells based on group III nitrides are in the focus of interest for the design of quantum cascade lasers and fountain lasers, which emit in the 1.55 µ m infrared spectral region. Thus they are important for future devices in the telecommunication. The design of low dimensional optoelectronic devices in hexagonal group III nitrides is complicated by spontaneous polarization fields along the c-axis. By growing cubic group III nitrides in the (001) direction this harmful effect could be avoided. Asymmetric cubic Al_xGa_1−xN/GaN double hetero-structures with different Al content were grown on 3C-SiC(001) substrates by radio-frequency plasma-assisted molecular beam epitaxy. For in-situ monitoring of the growth process reflection high energy electron diffraction (RHEED) was used. Clear RHEED oscillations were observed permitting an adjustment of the growth parameters to achieve good sample qualities. Furthermore ex-situ characterization was done by high resolution X-Ray diffraction and inter-band photoluminescence measurements taken at low temperature. The photoluminescence spectra provide four spectral separated emission bands, which clearly could be assigned to the specific layers. A partial stress in the barriers was measured, employing X-Ray diffraction reciprocal space maps (RSM) in the (113) direction.