FABRICATION AND STRUCTURE OF EPITAXIAL TERBIUM SILICIDE ON SI(111)

The epitaxial growth of terbium silicide by codeposition on Si(111) is demonstrated. Terbium and silicon are evaporated onto substrates held at room temperature and subsequently annealed up to 850-degrees-C, where the pressure during evaporation and annealing is maintained below 1 x 10(-9) Torr. Low-energy electron diffraction shows a sharp square-root 3 x square-root 3 pattern of the hexagonal silicide after an 850-degrees-C anneal. The morphology in these films in much improved over that of metal reacted layers with pinholes of < 0.15-mu-m in diameter. Rutherford backscattering analysis indicates single-crystal growth with a channeling minimum yield of 9% for 150-angstrom-thick silicide films annealed to 800-850-degrees-C. Plan view electron microscopy shows the evidence of faults along <220BAR> directions, but no indication of a superstructure in the silicide layer. The microstructure of the thick film is shown to be strongly affected by the formation of a template layer to thick film deposition.