Morphological, structural and optical properties of GaN grown on porous silicon/Si(100) substrate

In the present paper, we report results of GaN layers grown at 800 °C by metal organic vapour phase epitaxy (MOVPE) on porous silicon (PS) formed on Si(100) substrates. The surface morphology and the crystallinity of the GaN films were characterized by scanning electron microscope and X-ray diffraction. It was shown that GaN grows on PS preferentially on hexagonal polycrystalline form. The SEM observation reveals roughly surface textured by disoriented GaN grains having different shapes and sizes. The surface coverage and the wetting of GaN to PS are improved when the thickness of GaN layer increases. The optical properties of GaN layers were examined by PL and CL at low and room temperatures. Besides, the near edge-band (BE) emission, shows yellow (YL) and deep localized excitons bands at approximately 2.2 and 3.3–3.36 eV respectively. The depth CL analysis shows a spatial variation of the dominating YL and BE emissions as the electron beam energy rises from 3 to 25 kV.