Growth And Characterization Of Ga₂O₃ Thin Films By Halide Vapor Phase Epitaxy

As a new ultra-wide bandgap semiconductor material,Ga₂O₃ has a bandgap as large as 4.9e V and a critical breakdown electric field of 8 MV/cm.It is also has excellent chemical,mechanical and thermal stability at high temperature which makes its broad application prospects in UV emission/detection devices,high-power devices.In decades,most of the research on Ga₂O₃ thin films are focused on?-Ga₂O₃,but it is difficult to grow high-quality thin films on symmetrical heterogeneous substrates?such as sapphire?0001?and Ga N?0001??due to its monoclinic crystal structure.?-Ga₂O₃ is a ferroelectric material with wide bandgap and hexagonal crystal structure.Compared with?-Ga₂O₃,it is theoretically more suitable for the manufacture of new optoelectronic devices combined with wide bandgap hexagonal semiconductors?such as Ga N and Si C?.However,?-Ga₂O₃ couldn't be prepared using the melting method,because?-Ga₂O₃ has the phase transition at high temperature.The halide vapor phase epitaxy?HVPE?method has the advantages of high growth rate,uniform growth and relatively simple equipment,so it is very suitable for the growth of?-Ga₂O₃ materials.Aiming at the current research hotspots and difficulties of Ga₂O₃ materials,this paper adopts the HVPE system to carry out some research work on the preparation of?-Ga₂O₃ thin films.This paper mainly studied the structure,morphology,and optical properties of the?-Ga2O3 thin film.The main studies are as follows:1.We adopted the HVPE method to successfully grow the Ga2O3 film at 800?using metal gallium and high-purity oxygen as the gallium source and the oxygen source,respectively.The film was not a pure?-phase,but a mixed-phase film dominated by?-phase fraction and contained a small part of?-phase.When the growth temperature was 850?,the film was?-Ga2O3 single crystal film.2.At 800?,the transmittance of the gallium oxide film in the near-ultraviolet region exceeded 80%,and the transmittance in the visible region exceeded 85%.The obvious absorption edge was not generated until about 245 nm.The calculated band gap of?-Ga₂O₃ was about 5.06 e V.3.It was shown that the?-Ga₂O₃film is an island-like growth mode:three-dimensional?3D?islands merge to form a film.4.Both?-Ga₂O₃ and?-Ga₂O₃ unit cells contained Ga₂O₆ octahedron and Ga O₄tetrahedron,so the two-phase Raman peak position coincided.