Detection of a piezoelectric effect in thin films of thermally grown SiO2 via lock-in ellipsometry

We report the observation of structural piezoelectricity in partially ordered thin films of thermally grown silicon dioxide (SiO2). The piezoelectric coefficient was determined to be 0.14-0.26 pm/V, and the piezoelectricity was found to originate in a layer with thickness at least 3.5 nm. This value is consistent with literature descriptions of SiO2 residual ordering based on structural measurements and modeling. Our observation demonstrates that the residual ordering in thermally grown silicon SiO2 is non-centrosymmetric and provides a rare example of diffusion controlled uniaxial growth producing macroscopic piezoelectricity. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4731287]