Semiconducting Stress Transducers Utilizing the Transverse and Shear Piezoresistance Effects

Abstract

Principles of a varied group of new semiconducting, piezoresistive stress and strain transducers are outlined. These devices have in common the utilization of the transverse or shear piezoresistive effect. One group of devices consists of gauges in the form of a thin rectangular sheet which is bonded to the test piece, and whose resistance change can be expressed as a simple function of the principal stresses in the gauge. Two special gauges in this group are described. In one, the resistance change is proportional to the sum of the principal biaxial stresses for any orientation of the gauge on the test piece. In the other, the resistance change is proportional only to longitudinal stress components, being independent of transverse stress components. Also described are: a four-terminal gauge for complete determination of biaxial stresses, full-bridge gauges made from a single crystal, load cells of low compliance, new torque transducers, and diffusion techniques for making some of the foregoing. The devices are illustrated in terms of germanium and silicon but extension to other semiconductors is straightforward.