Giant Piezoresistance of Nano-Thick Silicon Induced by Interface Electron Traping Effect

Both n- and p-type nano-thick piezoresistors are fabricated on SOI (silicon on insulator) wafers using micro-fabrication processes. Giant piezoresistance is measured and theoretically explained for nano-thick silicon resistors. Compared to bulk silicon, one order of magnitude higher piezoresistive coefficients are, for the first time, tested with 13 nm-thick n-type and 9 nm p-type samples. Surpassing 2-D quantum effect, Si-SiO₂ interface electron trapping effect dominates the giant piezoresistance. Different from equivalent mobility change in conventional piezoresistance of bulk silicon, the giant piezoresistance come from carrier concentration change and have the same effect on the longitudinal and transverse piezoresistors.