Lattice sites and damage annealing of Er in low-dose implanted GaAs

We have used conversion electron emission channeling to determine the latti ce location of (167)mEr (t(1/2) = 2.28 s) in GaAs after 60 keV room tempera ture implantation of Tm-167 (t(1/2) = 9.25 d) at low doses (0.6-3 x 10(13) cm(-2)). Following a recovery step of the implantation damage at 200-300 de grees C, we observe a large fraction of Er (45-68%) on substitutional Ga si tes. A second fraction of Er is found on the T-As sites (the tetrahedral in terstitial sites with nearest As neighbours). The fraction on T-As sites re aches a maximum of 12-23% following annealing at 500 - 600 degrees C. At hi gher annealing temperatures the channeling effects decrease markedly, which we attribute to the well-known degradation of GaAs due to As evaporation. (C) 1999 Elsevier Science B.V. All rights reserved.