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 ?1015 cm-3, estimated iron concentration 6-8×1015 cm-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.