Investigation of the (Cu-Li)-related 2.172-eV bound exciton in GaP with optically detected magnetic resonance

Optically detected magnetic resonance (ODMR) is applied in this work to study the 2.172-eV bound exciton (BE) in GaP, associated with a complex neutral (Cu-Li)-related defect denoted (Cu-Li${)}_{\mathrm{V}}$. The ODMR data are analyzed with a spin-triplet spin Hamiltonian scrH=${\mu }_B$B⋅g${̃}_{\mathrm{ex}}$⋅S+S⋅D̃⋅S, ⋅S, where S is the effective BE spin. The best fit of this Hamiltonian to the ODMR data gives the values $g_x$=1.98±0.01, $g_y$=1.97±0.01, $g_z$=2.07±0.01; $D_x$=(-0.34±0.01)×${10}^{\mathrm{-}5}$ eV, $D_y$=(-1.04 ±0.01)×${10}^{\mathrm{-}5}$ eV, $D_z$=(1.38±0.01)×${10}^{\mathrm{-}5}$ eV, where x?[001], y?[11¯0], and z?[110] are the principal axes of the g and D tensors. The determination of these parameters is much more accurate than in previous work, where neither the principal defect axes nor the sign of the components of the D tensor were given. These improved data establish a $C_{2v}$ symmetry of the defect, with a different atomic and geometrical arrangement than proposed in previous work. With the combined information from the conditions of creation of the defect, the photoluminescence spectra and the ODMR data, it is suggested to be a three-atomic ${\mathrm{Li}}_{\mathrm{i}}$-${\mathrm{Cu}}_{\mathrm{Ga}}$-${\mathrm{Li}}_{\mathrm{i}}$ chain in a bent configuration in a {110} plane. The components of the g tensor for the BE are all close to g=+2, consistent with a spinlike character of both electron and hole. It is noted that the fit of the ODMR data with the spin-triplet spin Hamiltonian is quite good, and the influence of the nearby singlet state on the magnetic properties of the triplet state can be regarded as negligible.