Pair transitions in Zn3P2

Laser-excited photoluminescence emission has been measured from 2.5 to 100 °K for single crystals of Zn3P2 grown either by sublimation or by iodine chemical transport. Sublimation-grown crystals show two main peaks at 1.361 and 1.354 eV at 2.5 °K, each of which has a phonon replica displaced by 43 meV, and a third much smaller peak observable only above 20 °K at 1.367 eV. Iodine-transport grown crystals show a broad peak at 2.5 °K at 1.320 eV and its phonon replica displaced by 42 meV. The photon energy for peak emission shifts with excitation intensity as is typical of pair transitions, for the major bands seen at 2.5 °K. Temperature dependence measurements identify the donor and acceptor ionization energies corresponding to each of these bands.