Growth of thin Ti films on Si(111)-(7x7) surfaces

A study of the room-temperature growth of ultrathin Ti films [up to 7 monolayers (ML)] on clean and atomically flat Si(111)-(7X7) surfaces using Auger electron spectroscopy and low-energy electron diffraction (LEED) is presented. The variations in the Auger signal due to Si L(2,3)VV with binding energy of 92 eV are used to model the growth morphology of this system. These measurements indicate the growth of an initial disordered and continuous Ti film of up to 1.6 ML in thickness where the LEED pattern completely disappears and the Si Auger signal is strongly attenuated. As more Ti is deposited, this is followed by the disintegration of the continuous film and the formation of an intermixed Ti/Si film. This is evidenced by a change in the slope of the Auger signal time plot, and the reappearance of the LEED pattern. The modification in the overlayer composition for films thicker than 1.6 ML is confirmed by a change in the Si L(2,3)VV Auger peak that resembles the peak shape due to TiSi2. (C) 1996 American Vacuum Society.