Structure properties of GaN1-xPx ternary alloys grown by metal-organic chemical vapor deposition

GaN-rich side of GaN_1-xP_x ternary alloys have been successfully synthesized by light-radiation heating and low-pressure metal-organic chemical vapor deposition. The Ga 3d and P 2p core level peaks of the GaN_1-xP_x films show that P atoms in GaN_1-xP_x do partly occupy the N site but also is incorporated as interstitials of GaN_1-xP_x by means of X-ray photoelectron spectroscopy. X-ray diffraction spectra show that the (0002) peak of GaN_1-xP_x shifts to smaller angle with increasing P composition and the GaN_1-xP_x films are still of a typical hexagonal structure. The Raman spectra of GaN_1-xP_x films, recorded in backscattering geometry, exhibit four new vibrational modes at 256, 314, 377 and 428 cm^-1 compared with an undoped GaN sample. Those modes are assigned to the so called quasi-local mode induced by P in GaN, disorder-activated scattering and gap modes related to the Ga-P bond vibrations, respectively.