Optically detected magnetic resonance studies of donor‐double‐acceptor recombination processes in n‐type GaP crystals

We have studied luminescence and optically detected magnetic resonance (ODMR) of n‐type GaP crystals. Two luminescence bands at 1.5 and 1.7 eV, among which the 1.7 eV one decays faster than the other, are observed in the temperature range between 4.2 and 77 K. An ODMR signal, which shows the same photon‐energy dependence as the 1.5‐eV luminescence band, is found to have the characteristics of the electrons trapped by shallow donors. We suggest that the two luminescence bands arise from electron transitions from shallow donors to the same double acceptors: the 1.7 eV luminescence is to the doubly occupied acceptors and the 1.5 eV luminescence is to those half‐occupied.