SEGREGATION AND TRAPPING OF ERBIUM AT A MOVING CRYSTAL-AMORPHOUS SI INTERFACE

Segregation and trapping of Er during solid-phase crystallization of a morphous Si on crystalline Si is studied in a concentration range of 1 0(16)-5X10(20) Er/cm(3). Amorphous surface layers are prepared on Si(1 00) by 250 keV Er ion implantation, recrystallized st 600 degrees C, a nd then analyzed using high-resolution Rutherford backscattering spect rometry using 2 MeV He+ or 100 keV H+. The segregation coefficient k d epends strongly on Er concentration, At Er interface areal densities b elow 6X10(13) Er/cm(2) nearly full segregation to the surface is obser ved, with k=0.01. At higher Er densities, segregation and trapping in thr crystal are observed, with k=0.20. The results are consistent with a model in which it is assumed that defects in the a-Si near the inte rface act as traps for the Er. (C) 1997 American Institute of Physics.