Light sensitive SiGe MEM resonator for detection and frequency tuning applications.

This paper presents a silicon-based MEM resonant light sensor, a novel application for MEM resonators. The sensor is a particular kind of micro-bolometer in which the temperature increase of the heat absorber material is measured as a change in the resonant frequency, as opposed to the more traditional resistance measurement. A theoretical model, based on the finite element approach, will be presented together with measurements of fabricated sensors. The sensors were fabricated in a silicon-germanium (SiGe) based technology, with a 4µm thick structural layer. The sensors exhibited measured sensitivities up to 53 ppm/µW. From a theoretical analysis a temperature increase of 4.2K is predicted, which is in good agreement with the measured value of 5K.