【Epitaxy Papers】Optimization of α-Ga₂O₃ film via Mist-CVD: The role of droplet characteristics in 2D-3D crystal growth transition

      Researchers from the Shandong University have published a dissertation titled "Optimization of α-Ga₂O₃ film via Mist-CVD: The role of droplet characteristics in 2D-3D crystal growth transition" in Materials Today Chemistry.

Abstract

      Mist-CVD (Mist Chemical Vapor Deposition) is a promising technique for fabricating ultra-wide bandgap semiconductor gallium oxide films without requiring a vacuum environment, making it an attractive method for low-cost, high-performance semiconductor device fabrication. However, the films characteristics prepared by this method still require optimization to meet the stringent demands of electronic devices. In the process, the precursor solution undergoes ultrasonic atomization to generate microdroplets, which then react on the heated substrate surface, contributing to film growth. The behavior of mist droplets plays a crucial role in determining film quality, yet this relationship remains insufficiently underexplored. In this study, a microchannel Mist-CVD preparation system has been designed, through which the effect of mist droplet mass and heat transfer on the growth of single-crystal α-Ga₂O₃ have been explored by regulating the droplet characteristics, including velocity, size and number. Experimental results indicate that the optimal temperature occurs just before the phase transition point, where droplets are densely packed and have not undergone pre-reaction. By integrating theories of microchannel heat and mass transfer with crystal growth principles, correlations between the mist morphology and the 2D-3D crystal growth of α-Ga₂O₃ films have been established. Finally, an optimized strategy for low-cost, high-quality α-Ga₂O₃ film fabrication has been realized with full width at half maxima (FWHM) of 37 arcsec, root mean square (RMS) of 1.66 nm, and optical bandgap (E_g) of 5.32 eV.

DOI：

https://doi.org/10.1016/j.mtchem.2025.102853