Abstract
In this paper, we investigate electrodeposition of Pt, Pd and Au particles on n-Si using a double potential step method that applies single pulse potential of -1 to -8 V vs. SCE and then maintains constant potential at -0.3 V. An aqueous solution of H2PtCl6, PdCl2 or HAuCl4 at pH 1.7 is used for the electrodeposition of each metal. The particle density of Pt is increased with a negative shift of the pulse potential and then remains nearly constant. The Pd particle density changes with the pulse potential in a similar manner to the Pt particle case. The particle density of Au is much higher than that of Pt, and it is independent of the pulse potential. Immersion of bare n-Si wafers in the H2PtCl6 solution under the open-circuit condition deposits no particles but produces silicon oxide. Immersion in a H2PtCl4 (Pt(II)) solution, under the same condition as the H2PtCl6 (Pt(IV)) case, deposits Pt particles on n-Si. Immersion in a HAuCl4 solution deposits almost the same particle density of Au as electrodeposition. These displacement reactions, which involve cathodic reduction of metal ions and anodic oxidation of Si, influences the electrodeposition behavior.
