High bandwidth electron tunneling trasnducer using frequency downmixing readout of nanomechanical motion

Electron tunneling transduction based on quantum tunneling is very sensitive to the change of the distance from the probing tip apex to the sample surface and can be used as displacement transducer to detect the miniscule displacement of NEMS devices. However a limitation in electron tunneling transduction is the low detection bandwidth due to readout circuit frequency rolloff at a few 10's kHz. Here a novel electron tunneling transduction utilizing frequency downmixing directly in the tunneling junction overcomes the limitation of the detection bandwidth [1]. With this technique the high frequency vibration modes of doubly-clamped beams are measured, well above the RC rolloff of the STM measuring circuits.