X-ray reflectivity measurement of δ-doped erbium profile in silicon molecular-beam epitaxial layer

Synchrotron radiation x-ray reflectivity measurement is used to study the concentration profile of a {δ}-doped Er layer in Si epitaxial film grown by molecular-beam epitaxy. The oscillation of the reflectivity amplitude as a function of reflection angle is observed in the experiment. By doing a theoretical simulation, the concentration profile of Er atoms could be derived. It is shown that the originally grown {δ}-doped Er layer changes into an exponentially decayed function due to the Er segregation. The temperature dependence of the 1/e decay length indicates that the segregation is a kinetically limited process. The activation energy is determined to be 0.044±{}0.005 eV.