Luminescence of tungsten impurities in ZnSe

A new near-infrared luminescence band due to internal transitions of tungsten in ZnSe crystals is described. It is characterized by a weak zero-phonon line (ZPL) at ( nm) and 40 partially strong phonon satellites which reveal the presence of quasilocalized modes with energies of 33, 77, and . A magnetic field does not split the ground state, indicating that this is a state of a low-spin configuration of . The lifetime of the excited state is . Intense absorption bands around 12 000 and dominating the PLE spectrum are assigned to internal W transitions. Under excitation with ) a further emission appears starting at with a weak ZPL followed by several stronger phonon lines. The distances between these peaks coincide in some cases with the quasilocalized modes of the former emission. Therefore, this luminescence is probably also related to tungsten centres.