Raman Spectroscopy as an Effective Tool for Assessment of Structural Quality and Polymorphism of Gallium Oxide (Ga 2 O 3 ) Thin Films.

Raman spectroscopy, a versatile and nondestructive technique, was employed to develop a methodology for gallium oxide (Ga 2 O 3 ) phase detection and identification. This methodology combines experimental results with a comprehensive literature survey. The established Raman approach offers a powerful tool for nondestructively assessing phase purity and detecting secondary phases in Ga 2 O 3 thin films. X-ray diffraction was used for comparison, highlighting the complementary information that these techniques may provide for Ga 2 O 3 characterization. Few case studies are included to demonstrate the usefulness of the proposed spectroscopic approach, namely the impact of deposition conditions such as metal-organic vapor-phase epitaxy and pulsed electron deposition (PED), and extrinsic elements provided during growth (Sn in the case of PED) on Ga 2 O 3 polymorphism. In conclusion, it is shown that Raman spectroscopy offers a quick, reliable, and nondestructive high-resolution approach for Ga 2 O 3 thin film characterization, especially concerning phase detection and crystalline quality.