Investigation of thermal vibration correlation of [1Â 1Â 0] silicon lattice atoms by ion scattering

When a beam of fast ions hits an atom, a shadow cone is formed behind the atom. By varying the ion energy, the radius of the shadow cone can be changed and also the interaction probability between ions and lattice atoms. At strong vibration correlations, neighboring atoms are located almost inside the shadow cone and this acts to reduce the interaction probability. The Si-KL23L23 Auger electron emission was used to detect the reduction of the interaction between ions and lattice atoms, which is a measure for the vibration correlation. The yield of the Si-KL23L23 Auger electrons was measured as a function of the incidence angle around the [1 1 0] axis with ions. The correlation coefficient was determined by comparison of the minimum Auger electron yields with the results of computer simulations. It has been shown that the ion induced Auger electron emission can be used as a sensitive method for studying the thermal vibration correlation of a surface. The correlation coefficient of the normal displacement of nearest-neighbor silicon atoms along [1 1 0] at room temperature is determined to be 0.90.