Ballistic full-wave rectification: Separation of transport effects
Prof. Ulrich Kunze, Electronic Materials and Nanoelectronics, University of Bochum
- 10.02.2012 11:30 Uhr
- PGI-Hörsaal (Geb. 04.8, 2. floor)
Ballistic rectifiers are discussed as a possible technical application of ballistic transport. Such rectifiers allow full-wave rectification at zero cut-in voltage. At first the talk introduces the different transport effects that enable rectification operation, namely mode control, ballistic charging of a current-free lead by injecting electrons, and hot-electron thermopower. Depending on the device geometry these mechanisms may occur simultaneously, leading to a constructive or destructive superposition in the resulting output signal. The present devices are prepared from high-mobility AlGaAs/GaAs or Si/SiGe heterostructures. Different experiments are reported which target to separate the three mechanisms so as to evaluate their effectiveness separately. The rectifier efficiency is measured by two different figures of merit: The transfer resistance RT gives the ratio of output voltage and input current, the voltage efficiency η the ratio of output and input voltage. Present best values are RT ≈ 7 kΩ and η ≈ 60% for GaAs-based thermopower-type rectifiers and RT ≈ 950 Ω and η ≈ 15% for Si-based injection-type rectifiers containing a thermopower component.
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