Electrical transport properties of ultrathin disordered films

We report an experimental study of quench condensed ($2K\le T \le 15K$) disordered ultrathin films of {\rm Bi} where localisation effects and superconductivity compete. Experiments are done with different substrates and/or different underlayers. Quasi-free standing films of {\rm Bi}, prepared by quenching {\rm Bi} vapours onto solid {\rm Xe}, are also studied. The results show a dependence of the transport properties both on the dielectric constant of the substrate/underlayer as well as the temperature of quench condensation. RHEED studies indicate that quantum size effects are important in these systems. In this paper, we try to correlate the structure of the films to the transport properties obtained.