Studies of ultra-thin Bi films quench-condensed on solid inert gas and other substrates

This paper reports an experimental study of quench-condensed disordered ult ra-thin films of Bi, where localization effects and superconductivity compe te. Experiments are done with bare substrates and/or underlayers of solid X e, Ge and Sb. The deposition temperature is also varied. We have observed a bsence of superconductivity in low dielectric constant substrates even thou gh the sheet resistance is varied over 5 orders of magnitude. RHEED studies indicate that quantum size effects are important in these systems. Apart f rom stabilizing the amorphous phase in Bi, the Ge underlayer is found to nu cleate superconductivity when the Bi was quench-condensed at 15 K. The macr oscopic properties of the film are dependent both on the underlayer as well as the deposition temperature.