The mechanism of N-vacancy defects self-activated light emitting based on CaMg2N2

For resolving the problems existing in the self-activated nitride based phosphors, a self-activated orange light emitting semiconductor of CaMg2N2 has been successfully synthesized and investigated in details. The crystal structure of CaMg2N2 is formed by the face-shared MgN4 tetrahedron and CaN6 octahedron, implying its rigid host lattice. With the doped of R (R = La3+, Sm3+, Pr3+, Ce3+, Eu3+) ions, emission lights and XRD diffraction peaks all show a few shift except the excitation bands. The broad excitation bands all locate at 420 nm, which matches well with blue LED chips. The similar excitation bands have also been found in self-activated light emitting semiconductors of Li3AlN2 and Mg3N2, indicating the same defect (N related defects) existing in three matrixes leads to light emitting. Through investigating the crystal and electronic structures of three matrixes, N3- vacancies that can capture the electrons are deduced to act as luminescent center, which well explains the mechanism of self-activated light emitting nitride based phosphors. This conclusion has a guiding significance for improving the existing materials and researching the new LED materials.