Effects of temperature and tensile strain on the electrical resistance of nanometric gold films

The thermoresistivity and piezoresistivity of gold films with thicknesses of 10, 20, and 40 nm were analyzed. The films were thermally evaporated and deposited onto polyimide (Kapton (R)) substrates. Because of their nanometric thickness, the films required a post-deposition annealing to yield reproducible piezoresistive responses. Separation of each contributing factor and proper analytical models capturing the thermoresistivity and piezoresistivity responses were used for determining the gage factor (GF) and the temperature coefficient of resistance (TCR) of the films. The obtained GF values varied between 2.52 and 2.88, and the TCR values from (6.25 to 9.81) x 10(-4) degrees C-1. The TCR is about one fourth of the value typically reported for a bulk material. It was also observed that the electrical current used to measure the electrical resistance causes important heating of the films. These phenomena are relevant and must be taken into account in the case of electrical currents flowing through metallic nanofilms, either when designing experiments or as part of a device.