Tailoring the structural and optical properties of next-generation aluminum nitride thin films using CO₂ laser-assisted RF sputtering

Aluminum nitride (AlN) has recently garnered significant attention as a wide bandgap (WBG) semiconductor due to its high thermal conductivity, optical transmittance, electrical resistivity, and wide bandgap energy reaching up to 6.2 eV. Owing to these properties, AlN has become highly desirable for high-power electronic devices and deep-ultraviolet photonic systems. However, the fabrication of high-quality AlN thin films necessitates elevated substrate temperatures or additional post-deposition annealing processes, posing challenges for device integration and manufacturing compatibility. In this study, we demonstrate the deposition of high-quality AlN thin films without post-annealing by integrating a CO₂ laser into an RF sputtering system. To elucidate the influence of CO₂ laser energy density on thin film properties, structural and optical analyses were conducted. Structural and compositional characterizations were performed using X-ray diffraction (XRD), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and ultraviolet–visible (UV–Vis) spectroscopy. The optimized laser energy density significantly enhanced crystallinity suppressed defect formation, and refined surface morphology. Films exhibited high transmittance in the visible spectrum and an optical bandgap of approximately 5.94 eV at 0.70 W/mm², indicating improved crystallinity and reduced defect-related absorption. X-ray reflectivity (XRR) measurements revealed pronounced Kiessig fringes and film thicknesses in the range of ∼45–55 nm, confirming uniform and well-defined interfaces between the AlN film and the underlying substrate. Overall, these results accentuate the significance of CO₂ laser-assisted RF sputtering for controlling the properties of AlN films. These comprehensions analysis cover the way for their unified assimilation into next-generation electronic and optoelectronic devices.