Surface Morphology and Crystallographic Orientation of Electroplated Zn Film

Abstract

In this investigation, the surface morphology and crystallographic orientation of an electroplated zinc film is studied in regard to changes in plating conditions which include changes plating solution (ZnSO₄ bath, ZnCl₂ bath, and a mixed bath of these chemicals, as well as a Zn(CH₃COO)₂ bath and Zn(NO₃)₂ bath), kinds of substrate material (copper single crystal, and amorphous metal), thickness of the plating film, current density, pH of plating solution and additives. The electroplated zinc film has crystallographic coherency with a single copper crystal. On the amorphous metal substrate the initial zinc film is formed with an aggregation of small zinc crystals. The surface of the electroplated zinc film has a typical morphology depending on the kind of plating solution used. Generally, the surface roughness of the film increases with increasing of film thickness, and the morphology and roughness of the zinc film remains independent of changes in pH and plating temperature. The preferred crystallographic orientation of the film is generally 002, which is also independent of change in pH and plating temperature. The addition of p-cresolsulfonic acid in the bath largely changes the surface morphology and the preferred orientation, while addition of citric acid monohydrate in the bath changes the preferred orientation, but does not change the surface morphology. The preferred orientation of the electroplated zinc film is independent of surface morphology.