Giant Piezoresistance Measured in n-Type Nanothick Si Layer That Has Interface With $\hbox {SiO}_{2}$

A giant piezoresistive coefficient is, for the first time, experimentally measured for n-type nanothick silicon. Compared to n-type bulk silicon, the nanothick silicon resistors exhibit at least one order of magnitude higher piezoresistive coefficient. Based on 2-D quantum confinement effect, our theoretic calculation indicates that the piezoresistive sensitivity will decrease and approach to zero, along with continually thinning the n-type silicon resistor. Thus, quantum effect is not responsible for the giant piezoresistance of the n-type nanothick silicon. By phenomenon analysis and qualitative modeling, we attribute the obtained giant piezoresistance to stress-enhanced Si/SiO₂ interfacial electron trapping effect. Hence, the giant piezoresistance in n-type nano thick silicon is dominantly originated from electron concentration change, instead of equivalent mobility change in conventional piezoresistance of bulk silicon.