Optical studies of vanadium in gallium phosphide

The results of optical absorption, luminescence, luminescence excitation, and temperature-dependent Hall-effect measurements on semi-insulating n-type GaP:V and n-conducting GaP:V are reported. The VGa2+VGa3+ acceptor level is found at Ec - 0.58 eV. Absorptions due to photoionization transitions from and into this level can be identified. The absorption bands due to the transitions 3A2 → 3T1(F) and → 3T1(P) of VGa3+ are measured, both absorptions include three zero-phonon lines as well as phonon replica. At low temperatures the photoinduced rechargings VGa3+ <-> VGa3+ are investigated and interpreted in terms of the three charge states of VGa and the excitation of electrons from the PGa4+P4 anti-site centre. (author)