Optimization of Ga2O3 thin film growth via magnetron sputtering: Influence of growth pressure on crystallinity, surface morphology, and optical properties

Abstract

Gallium oxide (Ga₂O₃) thin films were successfully deposited on 6° off-axis sapphire substrates using RF magnetron sputtering, and the effects of varying growth pressures on structural, optical, and stress properties were systematically explored. AFM, SEM, and XRD analyses showed significant changes in surface roughness, film thickness, and crystal orientation as pressure increased from 5 to 15 mTorr. At 10 mTorr, the films exhibited the highest crystallinity, smoothest surface, and most uniform orientation. TEM and GPA revealed internal stress was minimized at this pressure, reducing stress-induced distortions. XPS analysis confirmed that the oxidation process is more efficient at specific pressures (e.g., 10 mTorr) compared to lower or higher pressures tested in the study. Optical measurements showed films deposited at 10 mTorr achieved the highest transmittance and largest bandgap, identifying 10 mTorr as the optimal condition for high-quality Ga₂O₃ films.