Identification of topmost atom on InP (001) surface by coaxial impact collision ion scattering spectroscopy

Abstract

The topmost atom of InP (001) surfaces, which were annealed at temperatures between 300 and 550°C or sputtered with 1 keV Ar⁺ at 300°C in ultra high vacuum, has been directly identified by means of coaxial impact collision ion scattering spectroscopy (CAICISS). Time-of-flight spectra of the annealed InP (001) surface exhibited both In and P peaks in both$[\overline {\text{1}} {\text{ }}10]$ azimuth and in [100] azimuth, which revealed that the topmost layer of annealed InP (001) was comprised of In-terminated and P-terminated surfaces. On the other hand, time-of-flight spectrum of the InP (001) sputtered at 300°C revealed only an In peak in$[\overline {\text{1}} {\text{ }}10]$ azimuth and revealed both In and P peaks in [100] azimuth. This result indicates that the topmost layer on the Ar⁺-sputtered InP (001) surface was completely terminated by In atoms. Furthermore, we indicate that surface damage induced by this sputtering treatment is little. The azimuthal depen-dence of CAICISS intensity scattered from In and P showed twofold symmetry with respect to [100] direction, which originated from the zinc-blende structure.