Optical Study of the Fe3+-Related Emission at 0.5 eV in InP:Fe

ABSTRACTThe 0.5 eV (2.5 μm 4000 cm1) emission band in InP has been studied by optical spectroscopy. By the use of Fourier-transform-infrared photoluminescence we have been able to observe at least a three-fold fine structure in the zero-phonon transitions at ∼ 4300 cm−1 which are studied at different temperatures. Based on the fine structure and the long decay time of 1.1 ms we ascribe the 0.5 eV emission to the 4T1 → 6A1 spin-flip transition of Fe3+. The excitation spectrum of this Fe3+-related emission shows a characteristic fine structure at ∼ 1.13 eV which belongs to a charge-transfer process of the type: Fe3+ + hv (1.13 eV) → [Fe2+, bound hole]. We discuss the excitation mechanism of the 0.5 eV emission by charge-transfer states and compare the results with an emission at 3057 cm1 in GaAs, which we attribute to the same Fe3+ transition (decay time: 1.9 ms).