Electron paramagnetic resonance studies of Mn2+ ions in β-Ga2O3 single crystal

A Mn2+ ion-doped β-Ga2O3 single crystal was grown by using a floating zone method. By employing an X-band electron paramagnetic resonance (EPR) spectrometer, Mn2+ EPR spectra were recorded at room temperature. The rotation patterns in the crystallographic planes together with spin-Hamiltonian parameters of Mn2+ show unequivocally that the actual local site symmetry of the Mn2+ ion is monoclinic. A Mn2+ ion lies on a site with a two-fold rotation symmetry, parallel to the monoclinic axis of the crystal. The spectroscopic splitting tensor g, zero-field splitting parameters Bkqs, and the hyperfine tensor A are determined with the effective spin Hamiltonian. It turns out that the Mn2+ ion lies at only one site, the substitutional site for the Ga3+ ion in the oxygen octahedron rather than in tetrahedron. Energy levels of the ground state for a Mn2+ ion embedded in the β-Ga2O3 crystal are calculated.