Dresden 2009 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 48: Poster 2
HL 48.68: Poster
Donnerstag, 26. März 2009, 15:00–17:30, P2
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
The influence of the electron density on the output characteristic of ballistic rectifiers is investigated.
The rectifier is a nanoscale four-terminal Ψ-shaped cross junction consisting of a straight voltage stem (200 nm wide and 2 µ m long) and two opposing 200 nm wide branches which merge under 45∘ into the central stem.
Different devices are fabricated from a high-mobility Si/SiGe heterostructure by using a mix-and-match process which combines high-resolution electron-beam lithography and UV-lithography. With a low-damage CF4/O2 plasma step the resist pattern is transferred into the heterostructure. After the preparation of ohmic contacts a nanoscale Schottky gate is locally deposited on top of the voltage stem.
A rectified inertial ballistic voltage develops between the upper and lower end of the central stem if a current is injected between the branches [1].
At T = 4.2 K we observe an increase of the rectified signal with decreasing electron density in the voltage stem achieved by applying a negative voltage at the local Schottky gate. The improved efficiency at low electron density is tentatively attributed to a reduced screening of the stationary dipole.
[1] M. Knop et al., Appl. Phys. Lett. 88, 082110 (2006)