Study of piezoresistance effect in nanotubes and applications

Piezoresistance is the tendency of a material to change its resistivity under strain. As a force deforms a crystal and changes the lattice spacing, the electronic band structure changes, which changes the resistivity. This effect is well understood in bulk semiconductors like silicon and germanium,[1,2] In this paper we study The resistivity of a semiconductor and a parameter which causes a shift in the population of carriers between subbands with different mobilities. In addition, the splitting suppresses band–band scattering because there are no longer phonons available with the correct energy and momentum. Another, smaller effect is a change in the overall band gap, which changes the number of carriers in the entire conduction band. The overall change in resistivity tends to be linear with strain. In nanotubes, on the other hand, the second-lowest subband of the conduction band is typically ~1 eV above the lowest subband,[3] so it is too high in energy to have any substantial carrier population. In nanotubes, piezoresistance is useful for mechanical sensors as well as electromechanical switches