Crystal anisotropy of elastoresistance effect of semiconductive piezoresistor and its application to transducers

An explicit equation which describes the strain-resistance relation, so-called elastoresistance, has been derived by means of piezoresistance and elastic coefficients. Typical examples of elastoresistance coefficients for p-Si have been calculated and illustrated as a function of crystal orientations in the principal crystal planes. The strain sensitivity of semiconductive piezoresistor and its dependence on the crystal orientation has been obtained from the illustration. As examples, a single transducer for a biaxial strain measurement and shear strain transducer have been explained. The optimum crystal plane and orientation for this purpose have been discussed.