The deposition layers of Ag, Au, Pd and Pt on porous silicon (PS) were prepared by the immersion deposition. The deposition bath was 0.5 mol•L^－1 HF aqueous solution containing noble metal salts and the deposition time was 20 s. Atomic force microscope morphologies showed that all the four noble metals could deposit on the PS, but the amount of Pt deposits was smaller than those of the others. Scanning electron microscope images and energy dispersive X-ray spectrometer analysis demonstrated that the deposition of noble metal occurred preferentially on the borders of pores, and the amount of noble metal depositing on the borders was 4.6 times as large as that on the bottoms. Electrochemical techniques presented that Pd and Pt, Ag and Au, respectively possessed similar properties in open circuit potential and A.C. impedance. Compared with others, the Pd deposit had distinct characters. Its oxidation current is one order of magnitude bigger than those of the others and its impedance is smaller than those of the others by one order of magnitude. This showed that the conductivity of Pd deposit/silicon heterojunction was higher than those of others due to the better adhesion of Pd on silicon substrate.

Key words: immersion deposition, noble metal, porous silicon