Physical Investigations of GaN/Porous Silicon at Different Laser Wavelengths

Abstract

In this study, we prepared PSi using the laser-assisted electrochemical etching method and deposited Gallium nitride (GaN) on the PSi substrate using the pulsed laser technique at different pulsed laser wavelengths (1064, 532, and 355 nm). We investigated the optical, structural, topographical, and morphological properties of Gallium Nitride on the substrate PSi by various pulsed laser wavelengths. The X-Ray Diffraction (XRD) analysis revealed that gallium nitride on PSi was polycrystalline and hexagonal, cubic structural at 532 nm, with a high peak intensity and crystallite size at 2θ=36.96°and 57.80 related to (101) and (110) planes, respectively, while the c-GaN phase is observed at 2θ = 25.43 degrees and is reflected from the (200) plane. PL shows two emission peaks were observed for the GaN film (430,345,413 nm) and the PSi substrate (867,891,876 nm), and the energy gap increased as the wavelength decreased. The field emission scanning electron microscopy (FESEM) pictures revealed that the synthetic sample had an average size of 24.45, 23.91, and 21.30 nm, and the nanoparticles appeared spherical and similar to cauliflower. The atomic force microscopy (AFM) results showed that the average roughness was 7.62, 10.64, and 13.62 nm, respectively, and it was observed the root mean square increased as a result of the uniform distribution of high-quality crystals and the excellent quality of the crystal structure. The UV-Visible (UV) results showed that the transmission decreased with a decrease in wavelength, and the absorption was inversely proportional to the transmission.