On the location of ytterbium in GaP and GaAs lattices

Abstract
Yb-implanted layers in GaP and GaAs were analyzed by Rutherford backscattering and channeling of 1.7-MeV 4He+ ions. It is shown that Yb diffused to the surface and formed precipitates in both crystals, and the nonsubstitutional fraction of Yb in furnace annealed samples exceeded 95%. Pronounced segregation of Yb to the surface in laser annealed GaAs was also observed. Nonsubstitutional location of rare earth ions and their out-diffusion from the crystals seem to be the main difficulties in obtaining III–V semiconductors doped with rare-earth elements.