Interaction of adsorbates with passivated Si surfaces studied by STM

Abstract

Skenovacia tunelová mikroskopia bola použitá na štúdium morfolgie táliovej vrstvy v rôznych štádiách desorbcie Tl z povrchu Si(111) a na štúdium správania sa rôznych adsorbátov na povrchu Si(111)/Tl-(1 × 1). Využitie táliovej vrstvy na pasivásiu povrchu Si(111) bolo bližšie skúmané pre rôzne druhy adsorbátov. Mangánové, hliníkové, indiové a cínové vrstvy, ktoré boli priamo deponované na Si(111)-(7 × 7), boli porovnané s vrstvami pripravenými depozíciou adsorbátu na pasivačnú vrstvu po následnej termálnej desorbcii tália z povrchu (po ohreve na teplote ≈ 400◦ C). Skúmané adsorbáty vykazovali známky extrémne vysokej difuzivity a slabej väzby k Si(111)/Tl-(1 × 1). Pasivačná vrstva bola voči ad- sorbátom stabilná. Aplikácia tália ako surfaktantu spôsobovala zníženie teploty a pokrytia potrebného na prípravu rekonštrukcií pozorovaných na povrchoch pripravených priamou depozíciou adsorbátu. 1

The scanning tunneling microscopy is used to study the morphology of Tl adlayer in various stages of Tl desorption from the Si(111) surface and to study behaviour of various adsorbates on the Si(111)/Tl-(1 × 1). The utilization of thallium layer for passivation of the Si(111) was examined closely for various adsorbates. Manganese, aluminium, indium and tin layers which were directly deposited onto the Si(111)-(7 × 7) were compared with the layers prepared by deposition of adsorbate onto the passivating layer after the subsequent thermal desorption of Tl (after annealing at ≈ 400◦ C). Examined adsorbates exhibited signs of extremely high diffusivity and weak bond with the surface Si(111)/Tl- (1 × 1). The passivating layer was stable against the adsorbates.The application of thallium in the role of surfactant caused lowering of temperature and coverage needed for the preparation of reconstructions which were observed on the surfaces prepared by the direct deposition of adsorbate. 1