Laplace transform photoinduced transient spectroscopy (LTPITS) has been
applied to study defect centres in Fe-doped and undoped semi-insulating (SI)
InP. A high resistivity (~ 2 × 107 Ω cm) of the latter was
by annealing at 950 °C for 40 h under a phosphorus overpressure.
It is shown that shallow donors in this material have an activation energy of
10 meV and are mainly compensated with deep acceptors characterised by
activation energies of 350 and 470 meV with respect to the bottom of the
conduction band. In the Fe-doped material, the shallow donors are compensated
with Fe-related deep acceptors having activation energies of 590 and 640 meV.