(001) β-Ga2O3 epitaxial layer grown with in-situ pulsed Al atom assisted method by MOCVD

Abstract

In this paper, to overcome the issues of high roughness and defect density in (001) β-Ga₂O₃ epitaxial films grown by MOCVD, a novel in-situ pulsed Al atom assisted growth method is proposed. Compared to films grown by conventional growth methods, the β-Ga₂O₃ epitaxial film grown using this method exhibited lower RMS roughness and a smaller FWHM of the (002) peak in the X-ray rocking curve. Additionally, oxygen vacancy defects within the film are significantly reduced, and Al incorporation is relatively limited without inducing lattice distortion. The width of serrations at the substrate-epitaxial layer interface is reduced from 70 nm to 17 nm, demonstrating improved interface flatness. The mechanism of pulsed Al atoms in optimizing homoepitaxial growth of (001) β-Ga₂O₃ is proposed, including their roles as preferential nucleation sites for Ga atoms, their inhibitory effects on Ga₂O formation and desorption, and the enhancement of atomic diffusion while minimizing parasitic side reactions. The phenomenon of epitaxial orientation rotation is observed, and a hypothesis is proposed regarding the causes of the difference in rotation angle and surface flatness. Additionally, Schottky barrier diodes (SBDs) are also fabricated to study the electrical properties of these epitaxial materials. The epitaxial layer obtained through the pulsed Al atom assisted growth method exhibited a breakdown field strength of 1.8 MV/cm. These results demonstrate that the pulsed Al atom assisted growth method may serve as a valuable reference for achieving high-quality (001) β-Ga₂O₃ epitaxial growth by the MOCVD method.