Time resolved investigation and resonant sub-harmonic driving of confined acoustic phonon modes in free-standing silicon membranes

MIKE HETTICH; AXEL BRUCHHAUSEN; RAPHAEL GEBS; FLORIAN HUDERT; DANIEL ISSENMANN; OLIVIER SCHECKER; REIMAR WAITZ; ARTUR ERBE; ELKE SCHEER; ADNEN MLAYAH; JEAN-ROCH HUNTZINGER; THOMAS DEKORSY

Regensburg, Alemania

Conferencia; Frühlingstagung – Deutsche Physikalische Gesellschaft (DPG-Spring-Meeting 2010); 2010

Deutsche Physikalische Gesellschaft (DPG)

The vibrational dynamics of thin silicon membranes have been investigatedby asynchronous optical sampling (ASOPS)[1].The small thickness of the silicon membranes leads to a confinementof the acoustic phonon modes and therefore to a discretization of thephonon frequency spectrum. Odd harmonics of the fundamental mode(19 GHz for a 221nm thick membrane) up to the 25th order have beenobserved [2].In order to measure the phonon lifetimes which exceed the measurementwindow of 1.2ns the repetition rates of the pump and probe laserare tuned to a subharmonic of the fundamental mode. By using thisapproach the phonon modes are resonantly driven and in analogy to amechanical resonator the lifetime and the quality factor of the phononmodes can be determined. We observe a Q-factor of 500 which is asignificant value for a nanomechanical resonator at room temperatur