The segregation and trapping of Er during the solid-phase crystallization of amorphous Si, on crystalline Si, was studied for Er concentrations ranging from 1016 to 5 x 1020/cm3. Amorphous surface layers were prepared on (100) Si by the implantation of 250keV Er ion, followed by recrystallization at 600C. The samples were analyzed by using high-resolution Rutherford back-scattering spectrometry with 2MeV He+ or 100keV H+. It was found that the segregation coefficient depended strongly upon the Er concentration. At Er interface areal densities of less than 6 x 1013/cm2, almost complete segregation to the surface was observed; with a segregation coefficient of 0.01. At higher Er densities, segregation and trapping in the crystal were observed; with a segregation coefficient of 0.20. The results were consistent with a model which assumed that defects in amorphous Si, near to the interface, acted as a trap for the Er.

A.Polman, J.S.Custer, P.M.Zagwijn, A.M.Molenbroek, P.F.A.Alkemade: Journal of Applied Physics, 1997, 81[1], 150-3