Semi-insulating behaviour of n-type lightly Fe-doped InP wafers after thermal annealing

As-grown Fe-doped semiconducting (SC) InP samples (residual carrier concentration /spl les/10/sup 15/ cm/sup -3/, estimated iron concentration 6-8/spl times/10/sup 15/ cm/sup -3/) were seen to convert to semi-insulating (SI), with high resistivity and good mobility, when annealed under appropriate conditions. This fact is very interesting since it gives the opportunity of obtaining semi-insulating InP with low Fe content. In this paper we report the annealing parameters together with the results of an extensive characterization (by Hall effect, C-V, IR absorption and PICTS) of the treated samples. The results suggest that the conductivity drop is related to a considerable loss of shallow donors.