Energy structure of Er-2O center in GaAs:Er,O studied by high magnetic field photoluminescence measurement

We perform photoluminescence measurement of GaAs:Er,O under a pulsed magnetic field up to 60 T and succeed to obtain the magnetic field dependence of three main photoluminescence peaks. We also estimate the energy splitting of states 4I15/2 and 4I13/2 using the crystal field theory. Theoretically calculated energy differences between the lowest state of J=image and the lowest three states of J=image are in good agreement with experimentally obtained energy of three main PL peaks. We discuss the local configuration around the luminescent Er-2O center. By using parameters in the crystal field calculation, our analysis suggest that not only O2− sites but also As3− sites adjacent to Er3+ ion are displaced from their original lattice positions.