Evidence for the leading role of the stacking-fault triangle in the Si(111) 1×1→7×7 phase transition

Abstract

In situ scanning-tunneling-microscopy (STM) observations at temperatures up to 600 °C provide atomic-scale evidence, demonstrating that the formation of the stacking-fault (SF) half-unit plays the leading role in the growth of 7×7 reconstructed domains of Si(111) surfaces from the 1×1 phase upon supercooling. The concept of the SF leading role accounts for the fact that all of the 7×7 reconstructed areas on Si(111) supercooled surfaces form triangular domains with vertices pointing in 〈1¯ 1¯2〉 directions. The STM data suggest that the formation of the SF half-unit involves the construction of dimer chains and corner holes. A similar leading role of the SF half-unit is also deduced to be fundamental for the growth of 5×5 or 9×9 metastable structures.