Effect of different laser energies on the structure of aluminum gallium nitride/Psi thin films

A photo-electrochemical etching method was employed to fabricate the porous silicon (PSi) substrate meticulously. Next, a thin layer of a high quality aluminum gallium nitride (AlGaN) target was precisely produced at 532 nm of laser wavelength, 50:50% of Al₂O₃ and GaN, 300 ⁰C of substrate temperature and different laser energies (600–1000 mJ) on this porous Si (PSi) substrate using the pulsed laser deposition process. By using X-ray diffraction (XRD) analysis, it was possible to identify the unique crystalline structure of the AlGaN thin film at 900 mJ of AlGaN structure with an average crystallite size of 23.2 nm. These diffraction angles, which correspond to the planes (002), (002), (101), and (103) plane, are 34.5⁰, 34.58⁰, 36.1⁰, and 36.13⁰, respectively. This method of deposition effectively enhanced the surface morphology and film quality. When examined with an atomic force microscope, oval particles were evenly distributed throughout the whole surface (AFM). The values of root mean square and average surface roughness increased from 600 to 900 mJ laser energy but decreased at 1000 mJ laser energy. Using a field emission scanning microscope (FESEM), images of the aluminum gallium nitride (AlGaN) layer deposited at 532 nm wavelength showed a uniformly covered porous silicon substrate. This proved that the spherical particles were distributed smoothly and uniformly. The thickness of the generated AlGaN nanofilms using 900 mJ laser energy during the PLD process was found to be roughly 2.426 μm. The AlGaN nanofilms were found to exhibit UV bands (345.9, 358.3, 361.2, 363.4, and 366.8 nm). Additionally, the AlGaN nanofilms produced with 900 mJ laser energy have a wavelength of 363.4 nm and an energy gap of 3.41 eV, which is closer than other laser energies to the theoretical value of E of GaN of 3.4 eV, all these results gives an indication to use the deposited AlGaN nanostructures in optoelectronic devices ans different sensors.