a b s t r a c tIn this paper, the theory of coupled plasma, thermal and elastic wave was used to study the vibration of semiconducting microcantilevers during photothermal process. The generalized thermoelastic model was adopted, along with plasma wave model, to obtain the vibration response of semiconducting microcantilevers under periodical laser excitation. The influence of thermal relaxation time on the vibration was investigated. The conventional and generalized thermoelastic theories for the temperature and deflection of microcantilever were compared. The simulation results for the amplitude and phase versus the modulation frequency revealed that near resonance frequency the generalized hyperbolic thermoelastic model was more suitable to describe the vibration characterization of microcantilevers than the conventional thermoelstic model.

An original approach for designing a one dimensional phononic crystal strip with an ultra-wide band gap is presented. The strip consists of periodic pillars erected on a tailored beam, enabling the generation of a band gap that is due to both Bragg scattering and local resonances. The optimized combination of both effects results in the lowering and the widening of the main band gap, ultimately leading to a gap-to-midgap ratio of 138%. The design method used to improve the band gap width is based on the flattening of phononic bands and relies on the study of the modal energy distribution within the unit cell. The computed transmission through a finite number of periods corroborates the dispersion diagram. The strong attenuation, in excess of 150 dB for only five periods, highlights the interest of such ultra-wide band gap phononic crystal strips.