Photosensitive Paramagnetic Resonance in Fe-Doped Gallium Phosphide

In iron-doped gallium phosphide two sorts of EPR spectra (denoted A and B spectrum here) have been observed: g =2.020±0.001, and g =2.131±0.002, for the A and the B spectrum, respectively. The A spectrum is attributed to the (3 d ) 5 configuration of substitutional Fe. The B spectrum seems to be attributed to the (3 d ) 7 configuration of Fe. The center corresponding to the B spectrum (B center) is not the center corresponding to the A spectrum (A center) which have trapped electrons, but an Fe impurity at a certain site of the lattice which have trapped a hole. Both spectra are photosensitive. Measurements of their photoresponse and temperature dependence have been made. They show that the activation energies of electrons and of holes for the A center are 0.5 eV and 1.7 eV, respectively.