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

► We study the energy structure of Er3+ ion in GaAs with O under a high magnetic field. ► Photoluminescence peaks are observed up to 60 T using a pulsed magnetic field. ► Photoluminescence peaks are discussed using the crystal field calculation results. ► The local configuration around the luminescent center Er is suggested.