Morphological and electrical study of gold ultrathin films on mica

Abstract

We present a topographical study of the formation of thin films of gold on muscovite mica. The characterization of the samples was done with scanning tunneling microscopy, atomic force microscopy as well as electric measurements. We performed our study on two groups of samples: first group of samples, evaporated at room temperature for thickness ranging from 1.5 up to 97nm; second group of samples, for two different thicknesses of 3nm and 50nm evaporated at different substrate temperatures, between 110 and 530K. The gold films show a Volmer–Weber growth. The complete films are obtained from samples with a nominal thickness of 8nm deposited. The average grain diameter is constant, with nominal thicknesses of 18.5nm, up to 8nm and increases with the thickness for higher deposition. The average grain diameter is similar regardless of the temperature of the substrate for samples of 3nm thickness, but changes for samples of 50nm thickness. The resistivity is inversely dependent on nominal thickness and the mean free path is lineally dependent on nominal thickness.