High-GF planar aluminium-silicon hybrid strain transducers

We demonstrate here a simple planar aluminium-silicon strain sensor incorporating an external aluminium ohmic shunt (metal-semiconductor hybrid) which exhibits a geometrically enhanced room-temperature gauge factor (GF) of up to 843 under uni-axial tensile strains of up of 8×10^-5 for a silicon p-type doping level of 1×10¹⁷cm^-3. We also show that the GF is dependent on the silicon doping density; a GF of 317 being demonstrated for a p-type doping density of 1×10²⁰ cm ^-3. Moreover a GF well above 1000 is possible in more lightly doped samples. The observed behaviour, to be contrasted with the gauge factor of -93 observed in homogeneous p-type silicon, is the result of the stress-induced anisotropy in the silicon conductivity that acts to deflect the current away from the metallic shunt for tensile strains.