GROWTH OF EPITAXIAL C54 TISI2 ON SI(111) SUBSTRATE BY INSITU ANNEALING IN ULTRAHIGH-VACUUM

Abstract

The growth of Ti and the formation of epitaxial Ti silicide on Si(111)-7 x 7 were investigated by using reflection high-energy electron diffraction (RHEED) and high-resolution transmission electron microscopy (HRTEM). The growth mode of Ti is Stransky-Krastanov type when the substrate temperature is room temperature (RT). On the other hand, it is Volmer-Weber type when the substrate temperature is approximately 550-degrees-C. The HRTEM lattice image and transmission electron diffraction pattern show that C54 TiSi2 is grown epitaxially on a Si substrate when 160 ML of Ti is deposited on a Si(111)-7 x 7 surface at RT followed by in situ annealing at 750-degrees-C for 10 min in ultrahigh vacuum (UHV). The TiSi2/Si interface is somewhat incoherent, but the developed TiSi2 crystallites are single crystal with matching face relationships of TiSi2(111) parallel-to Si(111), TiSi2(311) parallel-to Si(111), and TiSi2(022) parallel-to Si(111). A thin single-crystal Si overlayer with [111] direction is grown on the TiSi2 surface when TiSi2/Si(111) is annealed at approximately 900-degrees-C in UHV, which is confirmed by observing the Si(111)-7 x 7 RHEED pattern.