Electron spin resonance of erbium in gallium nitride

We performed electron spin resonance (ESR) measurements on Er-doped single GaN crystals synthesized from the solution of nitrogen in liquid gallium under high pressure of N2. The axial Er3+ spectrum was observed with g∥=2.861±0.003, g⊥=7.645±0.003, A∥=(110±5)×10−4cm−1, and A⊥=(290±5)×10−4 cm−1. The magnitude of an average g-factor gav=1/3(g∥+2g⊥) was nearly equal to the g(Γ7) ground state, as expected for Er3+ ions substituting for Ga in the GaN structure.