Theoretical investigations of EPR parameters and local structure of single erbium center in hexagonal GaN layers

Investigations of the spin-Hamiltonian parameters for Er3+ions in AlN crystal

“…The experimental " g(%6.54 [10]) for AlN : Er 3þ suggests that its ground state is À 5,6 . This point is different from that of Er 3þ in similar GaN crystal, where the observed " g % 6.05 [7,8] and the ground state is À 4 [8]. This suggests that the trigonal crystal fields for Er 3þ in AlN and GaN crystals are quite different.…”

“…Here we take the values of similar (ErN 4 ) 9À tetrahedron in GaN : Er 3þ [8], i.e. the Coulomb repulsions F 2 % 95 709 cm À1 , F 4 % 73 519 cm À1 and F 6 % 52 149 cm À1 , the two-body interaction parameters % 44.5 cm À1 , % À1073 cm À1 , % 1492 cm À1 , and the spin-orbit parameter % 2365 cm À1 .…”

“…Since the luminescence temperature quenching of Er 3þ -doped semiconductors strongly depends on the band gap of the host material and the III-nitride semiconductors (e.g. GaN, AlN) have wide band gap [3], the Er 3þ -doped III-nitride semiconductors have attracted considerable attention, and various spectroscopic studies have been made of these materials [6][7][8][9][10]. Recently, the electron paramagnetic resonance (EPR) spectra of Er 3þ -doped AlN crystal was measured and its spin-Hamiltonian (SH) parameters (g factor g // , g ?…”

“…The lowest-lying doublet may be À 4 or À 5,6, corresponding to the average value " g½¼ 1 3 ð g == þ 2g ? Þ of about 6 or 6.8, respectively [8,11]. The experimental " g(%6.54 [10]) for AlN : Er 3þ suggests that its ground state is À 5,6 .…”

“…This suggests that the trigonal crystal fields for Er 3þ in AlN and GaN crystals are quite different. The SH parameters of GaN : Er 3þ were explained from the perturbation formulas by Maalej et al [8]. No theoretical explanations for the SH parameters of AlN : Er 3þ have been carried out.…”