Epitaxial growth of β-Ga2O3 thin films on Ga2O3 and Al2O3 substrates by using pulsed laser deposition

In this work, we have successfully grown high quality epitaxial beta-Ga2O3 thin films on beta-Ga2O3 (100) and Al2O3 (0001) substrates using pulsed laser deposition (PLD). By optimizing temperature and oxygen pressure, the best conditions were found to be 650700 degrees C and 0.5 Pa. To further improve the quality of hetero-epitaxial beta-Ga2O3, the sapphire substrates were pretreated for atomic terraced surface by chemical cleaning and high temperature annealing. From the optical transmittance measurements, the films grown at 600-750 degrees C exhibit a clear absorption edge at deep ultraviolet region around 250-275 nm wavelength. High resolution transmission electron microscope (HRTEM) images and X-ray diffraction (XRD) patterns demonstrate that beta-Ga2O3(-201)//Al2O3(0001) epitaxial texture dominated the epitaxial oxide films on sapphire substrate, which opens up the possibilities of high power electric devices.