Electrical and optical properties of the neutral nickel acceptor in gallium phosphide

Abstract
Concentration measurements using the electron paramagnetic resonance (EPR) signature of the Ni3+ (3d7) state in GaP have been compared with thermal emission and photocapacitance data measured on the same samples. These data combined with EPR photo-quenching measurements provide a definitive assignment of a state with a thermal activation energy for hole emission of 510 meV to the Ni3+ to Ni2+ transition. The optical threshold for the same transition is 520 meV and the cross section for thermal capture of a hole into Ni2+ is 1.3*10-16 cm2 at 240K.