The piezoresistance effect of FIB-deposited carbon nanowires under severe strain

This paper reports the piezoresistance effect of carbon nanowires (CNWs) deposited by focused ion-beam-assisted chemical vapor deposition (FIB-CVD) using phenanthrene gas for the development of novel nanomechanical sensors. CNWs with diameters ranging from 88 to 129 nm were fabricated on electrostatic actuated nano tensile testing devices (EANATs) by FIB-CVD. EANATs can stretch CNWs using electrostatic comb drive actuators, and simultaneously measure the uniaxial tensile load and elongation of CNWs using the lever motion amplification system integrated into the EANATs. The average Young's modulus and fracture stress obtained for the CNWs were 69.2 GPa and 6.2 GPa, respectively. The resistance change in the CNWs with increasing uniaxial tensile strain indicated that the total gauge factor of CNWs was 0.7 below a tensile strain of 4%, but changed to −0.9 above 4%. An electrical conduction model for CNWs proposed in this paper was able to explain the resistance change in the nanowires and predict that the gauge factor for only the hydrogenated amorphous carbon region of CNWs ranged from −27.8 to −56.8