Uniform, self-organized, seven-step heightPb/Si(111)−(7×7)islands at low temperatures

Abstract

An unusual growth mode has been observed during low temperature growth at T=185 K in the system $\mathrm{P}\mathrm{b}/\mathrm{S}\mathrm{i}\mathrm{}\left(111\right)\mathrm{}-(7\mathrm{}\times 7)$ with the formation of uniform seven-step, steep-edged, flat-top islands up to coverages $\theta =7.5\mathrm{}\hspace{0.5em}\mathrm{ML}.$ The evidence is based on the spot profile analysis–low-energy electron diffraction diffracted intensity distribution as a function of $k_{\Vert },$ $k_z$ the parallel and normal components of the momentum transfer which show sevenfold oscillations over the range in $k_z$ where single step oscillations are expected. The formation of these highly uniform, self-organized structures implies that unconventional kinetic mechanisms operate at these low temperatures.