Study of Atomic Structures of Silicon Surfaces by Scanning Tunneling Microscopy

Abstract

Scanning tunneling microscopy (STM) is used to elucidate the atomic structure of a Si (111)√3×√3: Al surface and the solid phase epitaxy (SPE) processes of Ar-sputtered Si (100) surface. A √3×√3: Al structure is observed upon annealing at 580°C where Al adatoms occupy the T₄ sites. At a domain boundary between 7×7 and √3×√3 phases, Al adatoms are located in the unfaulted half of the 7×7 unit cell. The phase transition from √3×√3 to 7×7 structure occurred at the annealing temperature of 680_??_700°C. On the other hand, the 2×2 and c(4×4) reconstructed surfaces are observed upon annealing of amorphodized Si by Ar sputtering at 587_??_621°C. The possible arrangements of the missing-dimer defect are proposed to explain corresponding 2×2 and c(4×4) reconstructed structures.