Comparing schemes of displacement detection and subharmonic generation in nanomachined mechanical resonators

We present measurements on nanomechanical resonators operating in the radio frequency range. We apply a set-up which allows the comparison of two schemes of displacement detection for mechanical resonators, namely conventional power reflection measurements of a probing signal and direct detection by capacitive coupling via a gate electrode. For capacitive detection, we employ a preamplifier, mounted close to the sample and connected to it via bond wires, which enables direct measurements of the resonator's displacement. We observe that the response of the mechanical resonator depends on the detection technique applied, which is verified in model calculations. We show results for the detection of subharmonics.