Regensburg 2004 – scientific programme

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HL: Halbleiterphysik

HL 44: Poster II

HL 44.50: Poster

Thursday, March 11, 2004, 16:30–19:00, Poster A

Photoluminescence of GaAs/AlGaAs heterostructures grown in a manganese contaminated MBE system — •Klaus Wagenhuber, Hans-Peter Tranitz, Matthias Reinwald, and Werner Wegscheider — Institut für Experimentelle und Angewandte Physik, Universität Regensburg, Universitätsstr. 31, D-93053 Regensburg

Photoluminescence is a highly sensitive tool for the detection of residual impurities in semiconductor crystals. We used this technique to determine the quality of modulation doped single interface (MDSI) AlGaAs/GaAs structures. The samples were grown in an MBE chamber, which is also used for the epitaxy of GaMnAs layers. Manganese on a gallium-site forms a shallow acceptor level at about 0.11 eV above the top of the GaAs valence Band. Due to free-to-bound and donor-acceptor pair transitions a characteristic emission band appears at a well-known position of the luminescence spectrum. Our samples exhibit bright and narrow excitonic recombination lines in the PL-signal but even at high excitation densities no manganese peak could be observed. That leads to the conclusion that these layers are, to a high degree, free of the unwanted manganese impurity. Magneto-transport measurements show low temperature electron mobilities in excess of 5 · 10⁶cm²/Vs and thus confirm these results.

This work is supported by BMBF Verbundprojekt Spinelektronik und Spinoptoelektronik in Halbleitern