GaAlAs-based micromachined accelerometer

To develop micromachined accelerometers based on GaAlAs heterostructures, a selective etching procedure has been optimized as a function of structure and composition. The test structures (a GaxAl1-a,As (x = 0.32) alloy and sh ort period (GaAs)(9)-(AlAs)(4) superlattices) were grown on (001) GaAs subs trates. The strain gauge was deposited along the longitudinal direction of the micro-beam, with a width of 25 or 35 mum and the beam length ranging fr om 100 to 1000 mum. The measurements of piezoresistive properties were perf ormed for tensile strains by flexural tests. The gauge factors G (DeltaR/R- 0 = Ge), obtained for the GaxAl1-xAs epilayer can be estimated to be about 60. A complementary study was performed under hydrostatic pressure.