A theoretical study was made of a self-limitation of the surface segregation of Ge in epitaxial Si overlayers. This was attributed to the surface bond geometry on (100)Si during molecular beam epitaxy. It was found that Ge surface segregation was markedly limiting when the Ge concentration exceeded 0.01 of a monolayer. As a result of this self-limitation, the segregation profiles of Ge in Si overlayers decayed exponentially in the growth direction. There was a kink in the profile at about 3 x 1020/cm3; in good agreement with experimental observations. The kinetic barrier to Ge surface segregation was estimated to be 1.63eV.

S.Fukatsu, K.Fujita, H.Yaguchi, Y.Shiraki, R.Ito: Applied Physics Letters, 1991, 59[17], 2103-5