Long-Range Coherence and Macroscopic Phase Separation of Steps on Vicinal Si(111)

摘要

We present a synchrotron x-ray scattering study of a vicinal Si(111) surfacemisoriented by 3.3 toward the (1 Ii) direction. At temperatures above the first order 7 x 7 to 1 x 1 reconstruction transition temperature the surface contains coherent, thermally rough atomic steps in domains larger than 0.4 x 1 square micrometer. Below this temperature the surface phase-separates into macroscopic (II 1) facets larger than 0.4 x 1 square micrometer, and stepped regions where the step density increases as the temperature is decreased.