Synthesized aluminum Gallium Nitride/porous-Si thin films at different compositions by pulsed laser deposition method

In this study, AlGaN/porous silicon substrate was prepared using three different Al content (Al₂O₃: GaN) (25, 50, and 75) percent for a gas sensing application. A photo-electrochemical etching technique (PECE) created the porous silicon (PSi) substrate with the assistance of a diode laser. A thin layer of Aluminum gallium nitride (AlGaN) target was accurately synthesized on this porous Si (PSi) substrate at different concentrations of Al₂O₃: GaN (25,50 and 75%). The unique crystalline structure of the AlGaN thin film at (50:50%) of AlGaN with hexagonal structure was discovered by x-ray diffraction (XRD) analysis along the diffraction angles of 34.46°,34.52°, and 36.18° correspond to the planes (002), (002), and (103) plane respectively. This deposition technique precisely improved the film quality and surface morphology. Oval particles were uniformly dispersed throughout the surface under the atomic force microscope (AFM). The RMS and surface roughness increased to 25.3 nm and 21.5 nm, respectively, when the composition percentage was increased to (50:50) %. The Aluminum gallium nitride (AlGaN) film deposited at 532 nm wavelength was imaged using a field emission scanning microscope (FESEM) and revealed to have a uniformly covered porous silicon substrate. This demonstrated that round particles were dispersed evenly and smoothly. The AlGaN film (50:50) % structure has a thickness of 3.1 μm in its cross-sectional area, showing how precisely the deposition process worked. In UV photoluminescence (PL), The AlGaN nanofilms prepared with 50:50% composition of Al₂O₃: GaN has a wavelength of 360 nm and an energy gap of 3.44 eV, which was near band edge emission of GaN. As expected, the AlGaN peak related to the band edge transitions exhibited a blue shift with increasing Al₂O3 concentrations. The optical energy gap of the AlGaN thin film was discovered under UV-visible light. The resulting AlGaN showed energy band gaps of 3.2 eV, 3.44 eV, and 3.6 eV at 25,50, and 75% concentration, respectively.