Temperature coefficient of resistance and thermal expansion coefficient of 10-nm thick gold films

A methodology to simultaneously estimate the temperature coefficient of resistance (αR) and the thermal expansion coefficient (αT) of metallic films with thickness in the nanometric range in a film/substrate system is discussed. An analytical model which takes into account the thermo-resistivity and the piezo-resistivity effects to estimate αR and αT of metallic films from experimental data obtained at room conditions is proposed. The methodology is first validated by using 100-nm thick Au films which yields values close to the bulk, providing confidence on the reported values. The proposed methodology was used to obtain αR and αT of 10-nm thick Au films deposited by thermal evaporation with three deposition rates onto two substrates. The results show that for 10-nm thick Au films αR presents similar values than previous reports, meanwhile αT is between 5 and 6 times higher than the corresponding bulk value; the arrangement of the atoms during the films deposition yields only minor variation in such a thermal parameter.