Low-temperature synthesis and characterization of GaN nanocrystals from gallium trichloride precursor

Abstract

Gallium nitride (GaN) has been synthesized by reacting gallium trichloride with ammonia (NH3) at low temperatures ranging from 500 to 1000 °C for 12 h. X-ray diffraction, transmission electron microscopy, infrared, and Raman backscattering spectra revealed that the synthesized GaN powder consists of single-phase nano-sized crystallites with the wurtzite-type structure. The average size of the crystals decreases with the reaction temperature from approximately ∼63 nm at 1000 °C to ∼5 nm at 500 °C. GaOCl and ϵ–Ga2O3 are the intermediate products during synthesis of the GaN. Characteristic shifts of the Raman peaks are associated with the change in crystal size. The band-edge emission of GaN at 361 nm was observed on room temperature photoluminescence spectra exclusively for the sample synthesized at 1000 °C, while a new and broad emission band appeared with the center ranging from 827 to 765 nm for the samples synthesized between 500 and 800 °C.