High quality unintentionally doped n-type Al0.09Ga0.91N layers were grown on Si (111) substrate using AlN as buffer layer by radio frequency (RF) nitrogen plasma-assisted molecular beam epitaxy (PAMBE). This paper presents the structural and optical studies of porous Al0.09Ga0.91N sample as compared to the corresponding as grown AlGaN. The porous Al0.09Ga0.91N was prepared by Pt assisted electroless chemical etching using HF solution as an electrolyte. To assess the optical quality and morphology of these porous films, scanning electron microscopy (SEM), high resolution x-ray diffraction (HRXRD) and photoluminescence (PL) techniques have been employed. The porous area is very uniform, with pore diameter in the range of 100-150 nm. XRD measurements showed that
the (0002) diffraction plane peak width of porous samples was slightly broader than the as grown sample. As compared to the as grown film, the porous layer exhibits a slight increase in PL intensity.