STREAK PATTERNS IN LOW-ENERGY-ELECTRON DIFFRACTION ON SI(001)

The phase transition of Si(001) has been studied by investigating the temperature dependence of streak patterns in low-energy electron diffraction above the transition temperature. The streak pattern remains up to well above the transition temperature of c(4 x 2) to 2 x 1. The temperature dependence of the width and the length of the streak cannot be described by a simple two-dimensional Ising system. The result is discussed in terms of effects of a strong anisotropic coupling between adjacent asymmetric dimers, dimer vacancies, and a small amount of the p(2 x 2) configuration.