The use of SiO2 sublayers beneath titanium transition edge sensors for the purpose of phonon spectroscopy

We have investigated the effect of thin SiO 2 sublayers on the transmission of phonons into titanium transition edge sensors (TESs) fabricated on high-resistivity (100) float zone (FZ) silicon substrates. The response of a TES on native oxide is compared to that of an adjacent TES on a thermally grown SiO 2 sublayer. Latching current measurements indicate that thermal phonons are not attenuated by the film. However, pulse data from X-ray scattering experiments suggest that high frequency phonons are preferentially scattered.