Dresden 2003 – wissenschaftliches Programm
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HL: Halbleiterphysik
HL 34: Transporteigenschaften
HL 34.4: Vortrag
Mittwoch, 26. März 2003, 17:30–17:45, POT/81
Negativ differential resistance in a periodically and atomically precise modulated 2DEG — •T. Feil1, W. Wegscheider1, D. Schuh2, M. Bichler2, and G. Abstreiter2 — 1Institut für Experimentalphysik, Universität Regensburg, 93040 Regensburg, Germany — 2Walter Schottky Institut, TU München, Am Coulombwall, 85748 Garching, Germany
We investigate the negative differential resistance (NDR) in a periodically modulated 2DEG fabricated with the Cleaved-Edge-Overgrowth method. The negative conductance is attributed to Bloch oscillations of electrons in the first miniband. The numerically calculated miniband formation has been confirmed by magnetotransport measurements. Unlike in three dimensional superlattices the NDR does not lead to a hysteretical behaviour of the I-V-characteristics in the NDR-regime. This suggests that no electric field breakdown and subsequent charge domain formation takes place in our device. Numerical calculations for our samples based on the drift-diffusion-model confirm the experimental measurements. Due to the absence of domain formation we can study the transport dynamics of Bloch oscillations excited only by a constant electric field. Recently started microwave absorption experiments show a decrease in the peak current of the I-V-characteristics. This is attributed to the coupling of the Bloch oscillating electrons to the high frequency electric field. This project is supported by DFG via SFB348 and by BMBF 01BM918.