Piezoresistance of top-down suspended Si nanowires

Abstract

Measurements of the gauge factor of suspended, top-down silicon nanowires are presented. Thenanowires are fabricated with a CMOS compatible process and with doping concentrations ranging from2 × 1020 downto 5 × 1017 cm − 3. The extracted gauge factors are compared with results on identical non-suspendednanowires and with state-of-the-art results. An increase of the gauge factor after suspensionis demonstrated. For the low doped nanowires a value of 235 is measured. Particularattention was paid throughout the experiments to distinguishing real resistance change dueto strain modulation from resistance fluctuations due to charge trapping. Furthermore, anumerical model correlating surface charge density with the gauge factor is presented.Comparison of the simulations with experimental measurements shows the validity of thisapproach. These results contribute to a deeper understanding of the piezoresistive effect inSi nanowires.