YELLOW-GREEN LUMINESCENCE FROM ISOELECTRONIC NITROGEN CENTERS IN GAP GROWN BY MOLECULAR-BEAM EPITAXY

Molecular-beam-epitaxial growth of GaP incorporating isoelectronic N traps was achieved through coinjection of NH3 and PH3 which were dissociated into P2 and PN fluxes. The photoluminescence spectrum of a sample with a N concentration of approximately 2 x 10(19) cm-3 indicated that the dominant emission wavelength was at 5691 angstrom (2.18 eV), which is characteristic of the nearest-neighbor pair transition NN1. The spectrum of a sample containing approximately 2 x 10(20) cm-3 N atoms also displayed strong NN1 pair luminescence in addition to much stronger emission line at 5846 angstrom (2.121 eV), which is believed to be from a local mode outside the vibrational band. The peak intensity of this local mode was approximately 25 times greater than the peak emission of the NN1 line from the lighter doped sample.