Morphological investigation of ultrathin Ag and Ti films grown on hydrogen terminated Si(111)

Abstract

The growth of ultrathin Ag and Ti films on hydrogen terminated Si(111) has been investigated using electrical resistance measurements and atomic force microscopy (AFM). The films were deposited by electron beam evaporation at a rate of 0.01 nm/s under ultrahigh vacuum conditions at substrate temperatures from 130 to 550 K. The films were analyzed by in situ electrical resistance measurements during deposition and annealing, and by ex situ AFM characterization. The Ag films required approximately 5.5 nm to achieve electrical continuity at a deposition temperature of 130 K, whereas the Ti was found to produce electrically continuous films after deposition of 0.5 nm at room temperature. Film resistance and AFM measurements suggested island growth for Ag and layer by layer growth for Ti. The Ag island size of 10 nm films increased from a base area of approximately 2×103–9×103 nm2 with increasing deposition temperature from 300 to 550 K. The use of a 4 nm Ti buffer layer on the Si was found to significantly decrease the final roughness of the Ag films.