Optical properties of GaN:Tb nanoparticles synthesized by simple ammonification method

GaN:Tb nanoparticles are synthesized by simple ammonification of a mixture of Ga(NO3)3 and Tb(NO3)3. The XRD result shows that the sample predominantly presents hexagonal phase of GaN and its average grain size is 22.1 nm. TEM images show that the sizes of the particles are almost uniform. Besides conventional GaN Raman shifts, two extra peaks at 251 and 414 cm-1 observed in the Raman spectra can be attributed to the phonons activated by surface disorders or finite-size effects and vibration mode of N-rich octahedral Ga-N6 bonds, respectively. From photoluminescence spectra, four characteristic peaks of Tb3+ions are clearly observed: 5D4 →7F6(493.9 nm), 5D4 →7F5(551.2 nm), 5D4 →7F4(594.4 nm), 5D4 →7F3(630.1 nm).