Giant room temperature piezoresistance in a metal/silicon hybrid

TL;DR

This paper reports a giant room-temperature piezoresistance effect in a silicon/aluminum hybrid, with a gauge factor of 843, significantly surpassing bulk silicon, due to stress-induced anisotropy in silicon conductivity.

Contribution

The study demonstrates a novel giant piezoresistance effect in a metal/semiconductor hybrid, driven by geometrical arrangement and stress-induced anisotropy, not interface effects.

Findings

Maximum gauge factor of 843 at room temperature

Piezoresistance boost due to stress-induced anisotropy in silicon

Dependence of effect on hybrid's geometrical arrangement

Abstract

Metal/semiconductor hybrids are artificially created structures presenting novel properties not exhibited by either of the component materials alone. Here we present a giant piezoresistance effect in a hybrid formed from silicon and aluminum. The maximum piezoresistive gage factor (GF) of 843, measured at room temperature, compares with a GF of -93 measured in the bulk homogeneous silicon. This piezoresistance boost is not due to the silicon/aluminum interface, but results from a stress induced anisotropy in the silicon conductivity that acts to switch current away from the highly conductive aluminum for uniaxial tensile strains. Its magnitude is shown, via the calculation of hybrid resistivity weighting functions, to depend only on the geometrical arrangement of the component parts of the hybrid.