Electron paramagnetic resonance of Er3+ ions in aluminum nitride

An electron paramagnetic resonance (EPR) spectrum from Er3+ ions has been observed in a bulk single crystal of aluminum nitride (AlN). These Er3+ ions were introduced into the crystal during growth and had a concentration of approximately 2 x 10(16) cm(-3). The Er3+ EPR signal, monitored at 4.5 K, exhibits axial symmetry (the unique axis is parallel to the c axis in this wurtzite lattice) and shows well-resolved hyperfine splittings due to Er-167 nuclei. An absence of site splittings in the EPR angular dependence indicates that these erbium ions, replacing aluminum ions in the AlN crystal, have no nearby defects. Principal values for the g and hyperfine matrices are g(parallel to)=4.337, g(perpendicular to) = 7.647, vertical bar A(parallel to)vertical bar = 454 MHz, and vertical bar A(perpendicular to)vertical bar= 796 MHz. Forbidden transitions, appearing in the low-field portion of the hyperfine spectrum when the magnetic field is rotated a few degrees away from the c axis, give vertical bar P vertical bar=7.8 MHz for the nuclear electric quadrupole parameter. (C) 2009 American Institute of Physics. [DOI: 10.1063/1.3065532]