In situ Analysis of Ga-ultra Thin Films by TOF-LEIS

presentation

English

It is very well known that low energy ion scattering (LEIS) is a surface analytical technique capable of sensing the outermost monolayer on the surface. When a time-of-flight (TOF) detection is used, both scattered ions and neutral particles are detected and, hence, an information on deeper layers can be obtained as well. The TOF LEIS can thus be used for analysis of ultra thin films and for in-situ monitoring of their growth. In our group a unique ultrahigh vacuum (UHV) apparatus for deposition and in situ analysis of ultrathin films has been developed. Our recently published results on Ga grown on hydrogen terminated Si (111) proved the ability of TOF-LEIS to in-situ monitor the growth mechanism of ultra thin films as well as their thickness. However, Ga-film behaviour is complicated, it tends to form liquid metal droplets on silicon surfaces. To interpret the TOF-LEIS spectra correctly and to get a realistic view into the growth, computer simulation of ion beam scattering has to be carried out as well. Additionally, some complementary analytical techniques, particularly those for morphology and atomic structure determination should be applied as well. In our contribution, the results of an in situ study of growth mechanisms and thickness/morphology of gallium superstructures and ultrathin films on Si (111) and Si (100) substrates using TOF-LEIS, TDS, UHV AFM/STM and LEED will be presented. A special attention will be paid to finding the ratio between the growth mode/layer thickness and the shape of TOF-LEIS peaks being determined by inelastic and multiple-scattering processes.

TOF-LEIS, gallium, silicon, growth

KOLÍBAL, M.; PRŮŠA, S.; PLOJHAR, M.; BÁBOR, P.; POTOČEK, M.; TOMANEC, O.; MARKIN, S.; BAUER, P.; ŠIKOLA, T.

27. 6. 2005

Seville