In situ resistance measurements during physical vapor deposition of ultrathin metal films on Si(111) at room temperature

Abstract

The resistance of ultrathin metal films (Ag, Au, Cr, Ir, Pt, and Ti) on hydrofluoric acid-treated Si(111) surfaces is investigated during room temperature evaporation at very low deposition rates (0.003–0.006 nm/s). High-resolution in situ measurements are performed using the four-point probe technique. The authors find that, in addition to the type of metal, the resistance versus metal thickness characteristics heavily depend on the doping of the Si substrate. Furthermore, for most metals on p-type Si, the resistance initially increases as a function of deposition time. The authors explain this by a conductive path at the surface due to H-terminated Si bonds which are destroyed during deposition.

Influence of the nanostructure on the electric transport properties of resistive switching cluster-assembled gold films

“…The coverage percolation threshold ξ C should depend only on the dimensionality of the system [39] (ξ C ∿ 0.16 in 3D, ξ C ∿ 0.45 in 2D). In the case of atom-assembled films, the threshold value is close to the predicted value and in agreement with what is reported in literature [37]. This confirms that atomic-deposition favors the formation of 2D islands on the surface, forming large and connected structures.…”

“…Percolation curves acquired from evaporated gold, ns-Au/He and ns-Au/Ar thin films (Figure 7a) show that the drastic fall of resistivity happens according to particles dimension: first evaporated gold, in agreement with values reported in literature [37], followed by ns-Au/He and finally by ns-Au/Ar films. Small particles are more effective in forming large, well-connected regions during the film growth [27], reaching a fully percolated film at low thickness values.…”

Electrical conduction in nanogranular cluster-assembled metallic films

“…The early stages of film growth by atom assembling are characterized by the formation of isolated islands on the substrate [98]. The description of the electrical conduction mechanism at this stage is difficult since the experimental observations are averaged on the whole film constituted by several isolated aggregates [99].…”