Effect of oxygen content on piezoresistivity of indium tin oxide thin films prepared by pulsed laser deposition

The piezoresistivity of thin films of indium tin oxide prepared by pulsed laser deposition has been measured as a function of the O-to-(In+Sn) atom ratio. The oxygen-to-metal atom ratio was determined through Rutherford backscattering spectrometry and x-ray photoelectron spectroscopy analyses. Gauge factors, defined as the fractional change of the film resistance to the applied strain, increase with the film's oxygen content. The deposition under 50 mTorr oxygen pressure resulted in the film with the largest oxygen-to-metal atom ratio, 1.92, and a gauge factor of -14.5. A model based on hopping conduction is proposed. Results from this model are consistent with the sign and magnitude of the observed gauge factors. © 2005 American Institute of Physics.