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We have prepared the β-Ga2O3 nanofibres by electrospinning method followed by calcining in air at 900°C. The morphology and structure of the nanofibres are characterized by field emission scanning electron microscopy (FE-SEM), x-ray diffraction (XRD) and Raman technique. These nanofibres have diameters ranging from 60 to 130 nm and lengths up to several millimetres. Photoluminescence (PL) spectrum under excitation at 325 nm shows that these β-Ga2O3 nanofibres have a blue emission peaking at 466nm, which may be attributed to defects such as the oxygen vacancies, gallium vacancies and gallium-oxygen vacancy pairs.

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: D-5(4) -> F-7(6) (493.9 nm), D-5(4) -> F-7(5) (551.2 nm), D-5(4) -> F-7(4) (594.4 nm), D-5(4) -> F-7(3) (630.1 nm).

The amorphous GaN（a-GaN） films are deposited by direct current planar magnetron sputtering in different compositions of argon-nitrogen mixtures. X-ray diffraction patterns and the Raman spectra indicate that the films have amorphous structures. Spectroscopic ellipsometry shows that the refractive index and the film thickness increase with increasing argon content. The UV-Vis spectra indicate that the band gap of the film deposited without argon is 3.90eV, which is much larger than that of crystalline GaN （c-GaN）, owing to the structural disorder. When the films are deposited at higher argon content, the band gap becomes much smaller （2.80—3.30eV）, probably because of more excessive Ga in the films. The band tails extending to lower energies are modeled. Two parameters representing the energy broadening of the electronic transitions and the width or slope of the exponential tail are 0.257—0.338eV and 1.44—1.89?eV, respectively, which are higher than that of c-GaN films, indicating that a-GaN films have wider absorption tails than the c-GaN films. Photoluminescence peak at 360 nm observed at room temperature comes from band_to_band emission.

GaN:Er thin film has been prepared by direct current (DC) planar magnetron reactive sputtering deposition. The film was characterized by X-ray diffraction (XRD), ultraviolet—visible (UV—Vis) spectroscopy, transmission electron microscope (TEM) and photoluminescence (PL) spectroscopy, XRD shows the structure of the film was nano/poly-crystalline. The average grain size of the film was derived from XRD peaks using the Scherrer formula and the value was 58nm. TEM result indicated that the film was GaN nano-particles embed in amorphous matrix and the particle size was between 6—8nm. UV—Vis transmission spectrum shows that the transmission ratio of the film exceeds 80% in the visible zone from 500nm to 700nm. From UV-Vis spectrum, the optical band gap of the film was calculated using Tauc plot and the value was 322eV. Last, PL was measured by fluorescence spectrometer at room temperature and green emission of Er3+ ions was clearly observed for the transition: 4S3/2(2H11/2)—4I15/2(554nm).