Ag-metallization effects on optical and electrical properties of porous silicon

In this study, the chemisorption of Ag atoms to the porous silicon (PS) surface was studied with pre-metallization and post-metallization processes. The photoluminescence (PL), Fourier transform infrared (FTIR) spectroscopy and electrical properties of the Ag/PS samples via different metallization processes were examined. The PL spectra show a shift towards the high energy region in both of the metallized samples. According to the FTIR results, the Ag atoms coordinate themselves with respect to Si atoms on the surface through the oxygen and hydrogen atoms. The current–voltage characteristics were not examined in pre-metallization samples due to the aging effect of the oxygen atom and the trap levels in the contact Ag/PS interlayer. However, the current–voltage characteristics of post-metallization samples show a rectifying effect. Furthermore, the 10 s metallization sample shows an ohmic behaviour due to Ag atoms being adsorbed to the PS structure and Al contact material filling interlayer. It can therefore be concluded that optical and electrical properties of metal/Ag/PS/Si/metal structures are influenced by metallization time, i.e. pore diameter increases as the post-metallization time increases.