Extracting Piezoresistance in SiNWs using Thermal Induced Buckling of Micro-bridges

Abstract

AbstractThe recent reports on giant piezoresistance effect in highly resistive silicon nanowires (SiNWs) have offer greater sensitivity in stress measurements. Despite enhanced sensitivity, the piezoresistance of highly conductive silicon are preferred as they are less prone to thermal noises and hence better accuracy. Here we report a thermal induced buckle micro-bridge technique to accurately characterize the temperature dependent piezoresistivity effect in SiNWs. Phosphorus doped <110> SiNWs with 50 nm width, 95 nm thickness and 100 μm length were encapsulated within SiO2 micro-bridges. The electrical measurement of both reference SiNWs and SiNWs at micro-bridges was carried out, followed by the optical profiling of the micro-bridges with embedded SiNWs. N-type SiNWs with doping of 1×1020 ion/cm3 exhibit a strong dependence on temperature with a piezoresistive coefficient that decreases by 22.5 % between 25 oC to 60 oC; whereas its bulk counterpart is independent of temperature across this range. The results demonstrated that thermal noises may be more detrimental to nano-scale electromechanical sensors than its bulk counterparts.