Investigation of Er-related centers in doped GaP

The electronic and optical properties of Er-related center in doped vapor phase epitaxial GaP were investigated. Photocapacitance measurements revealed three Er-related transitions at 0.80, 1.27, and 1.50 eV. The transitions at 0.80 and 1.27 eV involve the direct excitation of Er³⁺ 4f shell electrons. The transition at 1.50 eV involves the excitation of an electron from the valence band to an Er-related trapping center. Photoluminescence excitation spectra of Er-doped GaP indicated three types of mechanisms for the excitation of characteristic 4f shell luminescence. Peaks at 1.27 and 1.55 eV were attributed to direct excitation of intra-4f-shell electrons, while the threshold of 1.50 eV is attributed to a valence band to Er³⁺ center transition.