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HL: Fachverband Halbleiterphysik
HL 10: Devices II
HL 10.1: Vortrag
Montag, 22. März 2010, 14:00–14:15, H13
Ballistic rectification in an asymmetric Si/SiGe cross junction with modulated electron density — •Daniel Salloch1, Ulrich Wieser1, Ulrich Kunze1, and Thomas Hackbarth2 — 1Werkstoffe und Nanoelektronik, Ruhr-Universität Bochum, D-44780 Bochum — 2DaimlerCrysler Forschungszentrum Ulm, D-89081 Ulm
We demonstrate a substantial efficiency increase in an injection-type ballistic rectifier due to a modulated electron density in its active region.
The rectifier is a nanoscale four-terminal Ψ-shaped cross junction [1] fabricated from a high-mobility Si/SiGe heterostructure.
Two nanoscale Schottky gates are locally deposited on top of the central stem above and below the cross junction.
In addition to the inertial-ballistic rectified voltage, which will develope between the upper and lower end of the central stem if a current is injected between the branches [1], a hot-electron thermopower voltage [2] establishes across the saddle-point potential formed below the local gate for negative gate-voltages [3].
At T=4.2 K we observe an increase of the rectified signal due to the superposed hot-electron thermopower for negative gate voltages. Depending on the position of the constriction in the stem, a sign reversal of the output signal is also demonstrated. Both signals are experimentally separated in a modified device geometry.
[1] M. Knop et al., Appl. Phys. Lett. 88, 082110 (2006)
[2] L. W. Molenkamp et al., Phys. Rev. Lett. 65, 1052 (1990)
[3] D. Salloch et al., Appl. Phys. Lett. 94, 203503 (2009)