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 β-Ga₂O₃ thin films on β-Ga₂O₃ (100) and Al₂O₃(0001) substrates using pulsed laser deposition (PLD). By optimizing temperature and oxygen pressure, the best conditions were found to be 650-700°C and 0.5Pa. To further improve the quality of hetero-epitaxial β-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°C exhibit a clear absorption edge at deep ultraviolet region around 250-275nm wavelength. High resolution transmission electron microscope (HRTEM) images and X-ray diffraction (XRD) patterns demonstrate that β-Ga₂O₃(-201)//Al₂O₃(0001) epitaxial texture dominated the epitaxial oxide films on sapphire substrate, which opens up the possibilities of high power electric devices.