Decoration of Semiconductor Surfaces for Electron Microscopy by Displacement Deposition of Gold

Publisher Website
Google Scholar
Abstract
The electrochemical displacement plating of gold on silicon in an HF solution has been studied by electron microscopy using a transfer replica technique. The gold deposits begin as localized nuclei whose diameters are equal to or less than 20 Å. At this stage of the plating process the gold nuclei show a preferred orientation corresponding to that of the substrate. During subsequent growth the orientation becomes random. The dissolution of silicon, which accompanies the deposition of gold, is generally independent of crystallographic directions and occurs in a random manner around the gold nuclei. Some p‐type specimens, however, reveal an oriented etch pattern. The preferred nucleation of gold at surface defects is demonstrated on cleaved specimens where the cleavage steps act as preferred sites for the nucleation. These steps sometimes form bands. Between the single steps or bands there are flat regions of random nucleation whose width can be as large as 2 μ. The nucleation density on these regions is the same as that on chemically polished specimens and is high, on the order of 1011−1012 cm−2. The preferred sites for nucleation, with the exception of surface defects, are probably related to surface states. The nucleation kinetics resemble an adsorption process. The growth is diffusion‐limited and the particle diameter is roughly proportional to the cube root of time.

This publication has 15 references indexed in Scilit: