Piezoresistance in silicon at uniaxial compressive stresses up to 3 GPa

The room-temperature longitudinal piezoresistance of n-type and p-type crystalline silicon along selected crystal axes is investigated under uniaxial compressive stresses up to 3 GPa. While the conductance (\(G\)) of n-type silicon eventually saturates at \(\approx 45%\) of its zero-stress value (\(G_0\)) in accordance with the charge transfer model, in p-type material \(G/G_0\) increases above a predicted limit of \(\approx 4.5\) without any significant saturation, even at 3 GPa. Calculation of \(G/G_0\) using \textit{ab-initio} density functional theory reveals that neither \(G\) nor the mobility, when properly averaged over the hole distribution, saturate at stresses lower than 3 GPa. The lack of saturation has important consequences for strained silicon technologies.