Simultaneous chemical silver and palladium deposition on porous silicon; FESEM, TEM, EDX and XRD investigation

Simultaneous palladium and silver deposition on porous silicon (PS) by immersion plating from aqueous [Pd(NH3)4]2+ and [Ag(NH3)2]+ complexes were carried out and studied by scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray analysis and X-ray diffraction. As the measurements revealed, the deposits were individual Pd and Ag seeds both in the pores and on the surface of the PS without forming Pd–Ag alloys. Palladium was present in the form of small spherical grains with diameter of 1–40 nm. In case of silver, two types of deposits could be distinguished. When high silver-complex ion concentration was applied, the deposition of Ag grains (d=60–100 nm) took place in the pores and on the surface as well. In case of lowered [Ag(NH3)2]+ concentrations, the formation of a three-dimensional porous silver networks (built up from silver particles of 30–40 nm in diameter)—on the top surface of the porous silicon layer—was advanced.