Effect of different laser wavelengths on the optical properties of GaN/PSi and Al₂O₃/PSi thin films using the pulse laser deposition method

In this work, gallium nitride (GaN) and aluminum oxide (Al₂O₃) nano-thin films were fabricated on the porous silicon (PSi) substrate. However, the porous silicon (PSi) substrate was synthesized in this study using a photoelectrochemical etching method. A thin layer of gallium nitride (GaN) and aluminum oxide (Al₂O₃) was deposited on the porous Si (PSi) substrate using the pulsed laser deposition method. This technique is employed at various wavelengths (1064 nm, 532 nm, and 355 nm) of Nd: YAG Q-Switched laser that works at a vacuum pressure of 10⁻² mbar, and the energy of the pulsed Laser is 900 mJ. The best results disappear when deposited at the 532 nm wavelength. The XRD investigation demonstrated that the GaN layer exhibits a distinct crystalline structure along the (002) plane, with a higher crystallite size of 18.9 nm, and the (311) plane, with a 19 nm crystallite size for Al₂O₃. This resulted in improved film quality and surface morphology. The field emission scanning microscope (FESEM) image, Energy Dispersive X-ray Spectroscopy (EDX), Atomic force microscopy (AFM), and photoluminescence (PL) spectra of gallium nitride (GaN) and aluminum oxide (Al₂O₃) films that were deposited at different wavelengths (1064, 532 nm, and 355 nm) were examined in this paper.