Dresden 2017 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 75: Poster Session: Transport 1
TT 75.27: Poster
Thursday, March 23, 2017, 15:00–19:00, P2-EG
Towards GHz reflection on a suspended carbon nanotube — Pascal Brunner, •Stefan Blien, and Andreas K. Hüttel — Institute for Experimental and Applied Physics, Universität Regensburg, Regensburg, Germany
Applying GHz signals as bias of a single electron tunneling device, as, e.g., a carbon nanotube, poses an obvious challenge. The impedance mismatch of typical radiofrequency electronics at Z0=50 Ω and a quantum conductor at ZL ≫ 6 kΩ leads to predominant signal reflection. This effect can be avoided by using an impedance matching network. A specific circuit which has already been successfully used to that purpose in literature is the so-called stub tuner.
We present low-temperature reflection measurements on stub tuner geometries intended for the in-situ growth of “ultraclean” carbon nanotubes as loads. The utilized superconductor is a rhenium-molybdenum alloy highly resistant to the nanotube growth process. For a load resistance of ZL=50 kΩ impedance matching is demonstrated with a return loss > 70 dB. The stub tuner properties are consistent with previous material characterization. Finally we discuss fabrication challenges for devices integrating in-situ grown carbon nanotubes.