Effect of strain on the frequency-dependent resistance of island gold films

Six different sets (A, B, C, D, E and F) of two-dimensional island gold films [2D-I(Au)Fs] were prepared by the thermal evaporation technique where Cornig 7059 glass slides, held at ambient temperature during deposition of gold atoms, were used as substrates. The mass thicknesses in nm for the films for each set were 0.5, 1.2, 2.4, 3.5, 5 and 10 for sets A, B, C, D, E and F respectively. After exposing the films to air at room temperature of 300 K, their d.c. resistance was monitored until the films attained short-term stable values. The effect of strain (ε) on both of the frequency-dependent resistance (rp) and the stabilized d.c. resistance have been studied for two modes of strain that were induced in the films. The first is the tensional longitudinal strain and the second is the compressional longitudinal one. It was found that: (i) at lower frequencies, rp increases with the increase in ε for the first mode while it decreases with the increase in ε for the second one. (ii) At higher frequencies, rp is independent on ε whatever its mode. (iii) The relative change in the d.c. resistance of the films varies linearly with ε for its two modes and thus the gauge factors for the films were simply deduced. Our results are, qualitatively, interpreted by: (i) considering the mechanism via which the charge carriers transfer among islands is tunneling. (ii) resorting to the known physical a.c. equivalent circuit of island metal films in general.