Conductivity conversion of lightly Fe-doped InP induced by thermal annealing: A method for semi-insulating material production

As-grown Fe-doped semiconducting InP wafers (residual carrier concentration ≤10¹⁵ cm^-3, estimated iron concentration 5-8×10¹⁵cm^-3) were converted to semi-insulating, with high resistivity and good mobility, when annealed under appropriate conditions. This fact is very interesting, since it permits the preparation of semi-insulating InP with an Fe content substantially lower than that of standard as-grown material. In this article, we report the annealing parameters, together with the results of an extensive characterization (Hall effect, C-V, infrared absorption, and photoinduced current transient spectroscopy) of the treated samples. The onset of the semiinsulating regime seems to be primarily due to an annealing-related loss of shallow donors.