NOBLE METAL ROW GROWTH ON SI (5 5 12)

摘要

We use scanning tunneling microscopy to study the growth behavior of Ag and Au on the highly anisotropic Si(5 5 12) surface. When low coverages of either metal (< 0.25 ML) are deposited onto Si(5 5 12) and annealed to moderate temperatures (～450℃), an array of overlayer rows occurs with an inter-row spacing of ～5 nm. Between these metal "nanowires," isolated Si π-chains from the underlying (5 5 12)―2x1 reconstruction remain undisturbed. At higher annealing temperatures (≈ 525℃), Au and Ag diverge in behavior to form two types of rows that are easily distinguished in STM images. In this case, the Ag rows completely remove all underlying Si structures near their vicinity. At higher metal coverages (> 0.25 ML), the surfaces form very different row-like phases, where Ag is significantly more ordered than Au. Under all conditions, we find that these noble metals grow as 1-D structures that result from the row-like morphology of the underlying Si(5 5 12) surface.