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HL: Fachverband Halbleiterphysik

HL 52: Nonpolar and Semipolar Nitrides

HL 52.5: Vortrag

Mittwoch, 16. März 2011, 12:45–13:00, POT 51

Highly spatially and spectrally resolved cathodoluminescence microscopy of planar semipolar InGaN/GaN MQWs grown on pre-patterned sapphire substrate — •Silvio Neugebauer¹, Sebastian Metzner¹, Frank Bertram¹, Thomas Hempel¹, Jürgen Christen¹, Stephan Schwaiger², and Ferdinand Scholz² — ¹Institute of Experimental Physics, Otto-von-Guericke-University Magdeburg, Germany — ²Institute of Optoelectronics, Ulm University, Germany

The optical properties of a 5-fold InGaN multiple quantum well (MQW) grown on planar semipolar (1122) GaN directly grown on pre-patterned r-sapphire substrate by MOVPE have been investigated using highly spatially and spectrally resolved cathodoluminescence (CL) microscopy. The sapphire was masked and structured via RIE generating grooves with c-plane-like sidewalls. Here the growth of GaN is initiated and single stripes are formed along the sapphire a-direction. The integral spectrum of the GaN substructure exhibits a dominant (D⁰,X) emission at 357,4 nm and a weak luminescence at about 361,7 nm related to basal plane stacking faults (BSFs). The BSF-CL was exclusively observed at the -c-wing of the stripes. Dark stripes in CL intensity image running from the c-plane-like sidewalls to the surface indicate bundles of dislocations acting as nonradiative recombination centers. In complete contrast, the area of the +c-wing exhibits a homogeneous CL distribution without any BSF contribution. The luminescence of the InGaN MQW shows three different emission wavelengths at 425 nm, 445 nm and 470 nm according to surface morphology.