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Keywords:

  • silicon nanosheet;
  • piezoresistivity;
  • microelectromechanical system;
  • nanoscale material;
  • first-principles calculation

Abstract

We have simulated the electronic states and piezoresistance coefficients in single-crystal silicon (Si) nanosheets on the basis of first-principles calculations of model structures. The carrier conductivities of the hydrogen-terminated Si nanosheet models with (001) surface orientation have been calculated using band carrier densities and their corresponding effective mass tensors derived from the two-dimensional (2D) band diagram by our original approach for a small amount of carrier occupation. The [110] uniaxial tensile stress causes band deformation, leading to the redistribution of carriers, and a drastic change of conductivity can be observed for nanosheet models. The p-type longitudinal and transverse piezoresistance coefficients about the [110] tensile stress swell up as the nanosheet becomes thinner, and we have obtained high piezoresistance coefficients of 343 × 10−11 Pa−1 of πl[110] and − 141 × 10−11 Pa−1 of πt [110] for about 1 nm thickness. It is expected that p-type ultra-thin Si(001) nanosheet will be a suitable candidate for nanoscale piezoresistors due to its giant piezoresistivity. Copyright © 2010 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.