Suppressing beam deflections by introducing phosphorous in the GaAs-based terahertz MEMS bolometers

We have investigated the effects of initial deflection of the doubly clamped beam on the responsivities of the recently proposed terahertz (THz) microelectromechanical (MEMS) bolometers. Although long beams are expected to have high responsivities, measurement results on the GaAs beam samples deviated from theory due to initial deflection of the MEMS beams. To suppress the beam deflection, we have introduced a preloaded tensile strain in the beam by adding a small amount of phosphorous in the GaAs beams. The observed responsivity shows a good agreement with theory, demonstrating that the initial beam deflection is reduced by introducing a tensile strain and that long MEMS beams are useful for high sensitivity measurements.