Interface energy of Au7Si grown in the interfacial layer of truncated hexagonal dipyramidal Au nanoislands on polycrystalline-silicon

Growth of truncated hexagonal dipyramidal Au nanoislands is reported by annealing Au/amorphous-Si/crystalline-Si at 1030 °C in oxygen and nitrogen ambient. Metastable gold silicide phase of ${\mathrm{Au}}_7\mathrm{Si}$ is observed to form at the interface of Au and polycrystalline Si, which was transformed from amorphous Si. Oxygen, acting as an impurity, inhibits outdiffusion of Si at the interface and thus controls the growth of Si deficient metastable phase of ${\mathrm{Au}}_7\mathrm{Si}$ in a diffusion-limited growth process. Interface energies of ${\mathrm{Au}}_7\mathrm{Si}$ (0.623–0.672 N/m) and ${\mathrm{Au–Au}}_7\mathrm{Si}$ (1.438–1.471 N/m) are derived from the contact angle measurements of the island structure involving Au and ${\mathrm{Au}}_7\mathrm{Si}.$