Optically detected magnetic resonance investigation of a deep Li-related complex in GaP

A broad photoluminescence (PL) band peaking at ≊1.70 eV in Li-doped GaP is investigated by optical spectroscopy. No electronic lines are observed for this PL spectrum, indicating a strong phonon coupling with a no-phonon energy of ≊1.80 eV. Optically detected magnetic resonance (ODMR) data reveal a triplet configuration for the lowest excited electronic state of the corresponding defect, which proves that it is a neutral complex defect, binding an exciton in a predominantly hole-attractive local potential with a compressive local strain field at the defect. The ODMR data can be fitted to a triplet spin Hamiltonian H=${\mu }_B$B⋅g⋅S+D[$S_z^2$-(1/3)S (S+1)]+E($S_x^2$-$S_y^2$) with evaluated parameters $g_x$=2.0, $g_y$=1.9, $g_z$=2.05, D=1.2×${10}^{\mathrm{-}5}$ eV, and E=8×${10}^{\mathrm{-}7}$ eV x∥[001], y∥[11¯0], z∥[110]. The defect, therefore, has a bent symmetry, and the identity is suggested to involve ${\mathrm{Li}}_{\mathrm{Ga}}$ together with two interstitials in a (110) plane, probably both Li atoms.