Effects of deposition environment and temperature on photoluminescence, particle morphology, and crystal structure of pulsed laser deposited Ga2O3 thin films

Gallium oxide (Ga2O3) thin films were laser ablation deposited on Si(100) substrates in vacuum, argon, and oxygen (O-2) at different substrate temperatures by using the pulsed laser deposition technique. X-ray diffraction patterns showed that the films were crystallized in a mixed phase of beta-Ga2O3 and Ga(OH)(3). Data from scanning electron microscopy and atomic force microscopy showed that the major influence in the deposition conditions on the photoluminescence (PL) intensity was through changes in the particle morphology and surface topography of the films. The surface morphology studied using a field emission scanning electron microscope showed that the films were made of nanoparticles of spherical and cubic shapes at lower and higher temperatures, respectively. The energy-dispersive x-ray spectroscopy spectra confirmed the presence of the major elements Ga and O, with C coming from atmospheric hydrocarbons and Si from Si impurity in Ga2O3 and the substrate. The Si peak intensity was found to increase with the deposition temperature. X-ray photoelectron spectroscopy further confirmed the presence of Ga, O, C, Si, and N on the surface of the films. The PL spectrum excited using a 325 nm He-Cd laser showed nanoparticle shape driven tunable broadband emissions in the wavelength range between 350 and 750 nm. The comparison of the PL intensities of the films deposited in different atmospheres shows that the film deposited in O-2 has the highest PL intensity.