Piezoresistance of carbon nanotubes on deformable thin-film membranes

Carbon nanotubes have interesting electromechanical properties that may enable a new class of nanoscale mechanical sensors. We fabricated two-terminal nanotube devices on silicon nitride membranes, measured their electronic transport versus strain, and estimated their band gaps and the strain-induced changes in them. We found band-gap increases and decreases among both semiconducting and small-gap semiconducting (SGS) tubes. The SGS band gaps exceeded the predicted curvature-induced gaps for their diameter. Some of the band-gap changes for both types of tubes exceeded the predicted maxima. These anomalies are likely caused by interaction with the rough silicon nitride surface.