Effect of beam deflection on the thermal responsivity of GaAs-based doubly clamped microelectromechanical beam resonators

Abstract

We have investigated how the beam geometry affects the thermal responsivity of doubly clamped GaAs microelectromechanical systems (MEMS) beam resonator structures. When the MEMS beam is heated, a thermal strain is generated and shifts the resonance frequency. MEMS beams with larger l/h ratios (l and h are the length and the thickness of the MEMS beam, respectively) have lower thermal conductances and are supposed to exhibit higher thermal responsivities. However, the induced thermal strain tends to be released by beam deflection for long GaAs beams, and as a result, long beams do not necessarily lead to high thermal responsivities. To reduce the beam deflection, we have introduced a preloaded tensile strain in the MEMS beam by using the lattice mismatch between GaAs1−xPx (x = 0.01) and GaAs. We find that the deflection of the GaAs1−xPx MEMS beam is suppressed and the responsivities increase with the increasing beam length, demonstrating that the introduction of tensile strain is useful for achieving high thermal responsivities predicted for long MEMS beams.