In this paper we report results from electrical and optical measurements carried out on GaAs:Yb, Er.
For GaAs:Yb electrical experiments such as photoconductivity (PC) and Photo Induced Current Transient Spectroscopy (PICTS) show that there is a level at 0.65eV related to Yb. This explains why no Yb3+ photoluminescence (PL) emission is detected, the recombination energy of the trapped excitons is too low (≈ 0.6eV) to excite the Yb3+ internal transition(≈ 1.24eV). We also present results on Er doped GaAs materials. From PL experiments we deduce an estimate of 10−19cm2 for the stimulated emission cross section. By PICTS and PC, we have evidenced a trap at 0.67eV related to Er ions in GaAs. And we think that in this case, the rare earth ions are excited via formation of bound excitons.