Zeitaufgelöste STM-Untersuchungen zur Silizid- und Metall-Epitaxie der Systeme Fe-, Cu-, Pt/Si(111) und Cu/W(110)

Reshöft, Klaus

An in situ and MBE-capable high temperature STM and integrated MBE-evaporator cells for the metal species Fe, Cu and Pt have been constructed. Nucleation and growth of Fe-, Cu- and Pt-silicides on the Si(111)-(7x7) surface and of Cu on W(110) have been investigated directly during the MBE-deposition by in situ time-resolved STM. Venables nucleation theory has been applied to the first two systems in order to estimate specific quantities of the nucleation process. s. Fe/Si(111) exhibits in the temperature range 235-560°C three morphological different types of nuclei with (2x2)-, c(8x4)- and a distorted pseudohexagonal reconstruction. The last type occurs only in a star-shaped 3-domain structure. Different silicide phases are discussed, considering the vertical layer growth, stoechiometric composition and the observed phase transformations. Fe-depositions at lower temperatures of 170°C and RT show an amorphous cluster growth. h. For Cu/Si(111) nuclei with quasi-(5x5)-reconstruction originate above 120°C. This phase is affected by a temperature dependent ordering phenomenon, which influences the azimutal orientation, stoechiometry and period length. h. Pt/Si(111) developes in the temperature range 385-445°C different successive structures. First occurs a (root{3}xroot{3})R30°-phase, second a (root{13}xroot{13})R13.9°-phase, finally structure types with quasi-(3.2x3.2)-, (5x5)R0°-, (root{13}xroot{13})*R13.9°-reconstruction and Stranski-Krastanov islands. Above 400°C the last mentioned phases exist only metastable. Phase transformations lead to the formation of a (root{7}xroot{7})R19.1°-phase. e. For the system Cu/W(110) a sequence of three different structures is needed to transfer the Cu-film to its ts intrinsic fcc-like behavior. The first, second and third layer are related respectively to a pseudomorphous structure with fractal geometry, a strained structure exhibiting a periodic trench network and a slightly expanded fcc-Cu(111) layer showing a periodic dislocation network. SPA-LEED has been used to obtain precise information about the lateral geometrical dimensions. Structure models are suggested.



Citation style:

Reshöft, Klaus: Zeitaufgelöste STM-Untersuchungen zur Silizid- und Metall-Epitaxie der Systeme Fe-, Cu-, Pt/Si(111) und Cu/W(110). 2001.


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