Effect of the synthesis conditions on the properties of Co embedded porous Si nanostructures

Highlights: • The effect of the synthesis conditions on properties of porous silicon/Co is studied. • Size and shape of Co nanoparticle vary with the deposition time and current density. • XRD and Raman spectroscopy have also confirmed the presence of the Co nanostructures. • The origin of the improved PL signal from porous silicon/Co is also discussed. • Deposition time has a strong effect on light emitting properties of porous silicon/Co. -- Abstract: The electrodeposition of cobalt in the porous silicon (PSi) substrate was investigated in terms of the deposition times and current densities. The PSi/Co samples were characterized by SEM, XRD, Raman, and photoluminescence (PL) spectroscopies. The results indicated that for all current densities, the PL intensities of PSi/Co samples with shorter deposition times (t_s ≤ 20 min) increased due to spherical Co nanoparticles (NPs) could be created the new recombination centers, compared to that of the undeposited PSi. On the other hand, the PL intensity of PSi/Co samples significantly decreased at longer deposition times (t_l > 20 min) because of larger Co NP cluster promoted the formation of non-radiative centers. The increased PL intensities in samples with t_s were attributed to both the quantum confinement effect and surface effects. PL analyses also suggested that after exposure to air for 60 days, PL characteristics of PSi/Co were stabilized depending on deposition time and current density.