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HL: Halbleiterphysik

HL 8: Heterostrukturen II

HL 8.3: Vortrag

Montag, 11. März 2002, 16:00–16:15, H14

Intersubband resonance in tunneling coupled double quantum wells — •S. Holland, K. Bittkau, C. Zehnder, C.-M. Hu, C. Heyn, and D. Heitmann — Institut für Angewandte Physik und Zentrum für Mikrostrukturforschung, Jungiusstrasse 11, 20355 Hamburg

GaAs/AlGaAs based tunneling coupled double quantum wells have been grown with molecular beam epitaxy (MBE). The system was investigated with FIR transmission spectroscopy with a magnetic field up to 12 T at 2 K. A grating coupler with a periodicity of 2 µm on top of the sample made the excitation of the intersubbband resonance (ISBR) possible. The charge density could be varied with a Ti front gate.

We observe the ISBR from the first antisymmetric subband 1_AS to the second symmetric subband 2_S. With changing the magnetic field we see a filling factor dependent oscillation of the resonance position at charge densities of 7·10¹¹cm⁻² - 7.9·10¹¹cm⁻². This behaviour is explained by a change of the selfconsistent potential because of alternating occupation of Landau levels which belong to the symmetric and the antisymmetric subband 1_S and 1_AS, respectively.

At lower densities (4.6·10¹¹ cm⁻² - 5.9·10¹¹ cm⁻²) we observe between 5 T and 8 T two ISBR which arise from a splitting of the 1_AS induced by disorder.

We would like to thank the BMBF, the DFG, the SFB 508 and the NEDO program for spintronics for financial support.