Magneto-optical studies of the 0.88-eV photoluminescence emission in electron-irradiated GaN

Properties of the 0.88-eV photoluminescence (PL) in electron-irradiated wur tzite GaN have been investigated in detail by a combination of various magn eto-optical techniques, including Zeeman measurements of FL, optically dete cted magnetic resonance (ODMR), and level anticrossing (LAC). ODMR observed by monitoring the PL emission is demonstrated to originate from a spin tri plet. The symmetry of the corresponding defect is shown to be rhombic with its principal axes pointing into the high-symmetry directions Z = [0001], Y = [1 (1) over bar 00], and X = [11 (2) over bar0]. From the Zeeman measure ments the emission is shown to arise from an optical transition between a s inglet excited state and the singlet ground state, providing convincing evi dence for indirect detection of the spin triplet ODMR. LAC investigations o f the same PL emission reveal two LAC lines, among which one is related to the spin triplet detected in ODMR.