STRUCTURAL TRANSFORMATIONS AT ROOM-TEMPERATURE ADSORPTION OF IN ON SI(111)ROOT-3X-ROOT-3-IN SURFACE - LEED-AES-STM STUDY

Low energy electron diffraction (LEED), Auger electron spectroscopy (A ES) and scanning tunnelling microscopy (STM) have been used to study t he evolution of the surface structure upon room temperature deposition of In onto In-predeposited Si(111) root 3 x root 3-In surface. The se quential formation of the Si(111)2 x 2 and Si(111)root 7 x root 3 surf ace phases has been detected and coverage ranges of their existence ha ve been determined. STM observations have revealed that the Si(111)2 x 2-In phase has a honeycomblike atomic structure with depressions in T -4 positions. The structural model built of In trimers has been propos ed. The ''low-temperature'' Si(111)root 7 x root 3-In phase shows up i n STM images as parallel rows of protrusions and its structure has bee n found to differ from the structure of the known ''high-temperature'' Si(111)root 7 x root 3-In phases. The inheritance of the defects at t he structural transition from root 3 x root 3 structure to 2 x 2 struc ture has been discussed. (C) 1997 Elsevier Science B.V.