Corresponding planar TEM micrographs of the two samples are also reported in the inserts of Figures. Electron diffraction (SAED) of AuNP as shown in the support information document 1 (Fig. 2) presents a bright spot along the (400) Si direction on the (200) Au ring, representing the heteroepitaxial arrangement of Au atoms deposited, as previously reported. The intensity of this point is reduced after hydrofluoric acid treatment, so it can be assumed that the flat gray region and the substrate orientation are heteroepitaxial. The 3D arrangement of the Au atoms after hydrofluoric acid treatment indicates partial loss of the heteroepitaxial relationship with the substrate.

In addition, the amount of Au on the sample measured using RBS did not change even after 70 seconds of hydrofluoric acid treatment, indicating that the atomic arrangement was not associated with the dissolution of the deposited gold atoms.

For a better understanding of the processes taking place in hydrofluoric acid impregnation, we prepared samples with large, flat areas, followed by a short period of hydrofluoric acid pretreatment followed by 20 seconds of immersion in the plating solution. In the high-angle annular dark field imaging (HAADF) Z-contrast (atomic number) imaging mode, the gold morphology was examined by planar TEM and scanning transmission electron microscopy (STEM) Figures 4a and 4b are plane TEM of the sample before and after the hydrofluoric acid deposition treatment for 70 seconds. A more pronounced effect is a significant change in the fractional coverage area, which varies by about 15%. By using a STEM detector (HAADF detector) with a large inner radius, electrons that are not Bragg scattering are collected. Because such HAADF images show little or no diffraction effect and their intensities are approximately proportional to Z2. The post-hydrofluoric deposition treatment imparted a uniform intensity distribution to the corresponding STEM micrographs, indicating a more uniform thickness of the gold particles, as can be clearly seen by comparing Fig. 4c and Fig. 4d, respectively.