POLYCRYSTALLINE SILICON AS A STRAIN-GAUGE MATERIAL

A theoretical model for piezoresistance in both n- and p-type polycrystalline silicon is described. This model considers the contribution to piezoresistance from the grain and the Schottky-type barrier regions around the grain boundaries. Transport across the grain boundaries. Transport across the grain boundary is assumed to be dominated by thermionic emission. The change in conductivity is due to a shift in the relevant conduction and valence band minima and maxima relative to each other, resulting in a redistribution of the carriers between minima or bands. This shift will result in a change in contribution to thermionic emission from the minima or bands and thus change the conductivity of the barrier.