Characterization of β-Ga2O3 films deposited under different growth temperature by pulsed laser deposition

A series of beta-Ga2O3 films were prepared on polished Al2O3 substrates by pulsed laser deposition at temperatures between 580 and 780 degrees C were characterized by X-ray diffraction, atomic force microscope, scanning electron microscope, spectrophotometer, and spectrofluorometer. As the growth temperature increases, the phase changed from amorphous to polycrystalline beta-Ga2O3 structure, the thickness of beta-Ga2O3 films decreases from 173 to 137 nm, and the average grain size increases from 14.2 to 34.7 nm. The band gap of beta-Ga2O3 film deposited at 780 degrees C is calculated to be 4.88 eV which is close to the Ga2O3 bulk. The photoluminescence intensity increases with the increasing growth temperature and the spectra can be divided into four emission bands located at UV and blue region, which are due to the recombination of self-strapped holes at O(1) sites and between two (O)2-s sites, and tunneling-trapped holes from V-Ga(2-) at Ga(1) tetrahedral sites.