Au/amorphous Si/SiO2/Si structure was used as substrate for diamond deposition by microwave plasma CVD. The Au-Si phase diagram shows a eutectic point at 363 °C. At deposition temperatures of 700-800 °C, the Au and amorphous Si films were alloyed as liquid during deposition, which resulted in formation of an array of single crystalline Si whiskers. Microstructural characterization shows that the Si whiskers have a diameter in the range of 50 nm-5 μm with facet on the top surface. The Si whiskers are shown to be oriented along 〈311〉 directions. Diamond particles deposited are found only on top of the Si whiskers. The diamond particles can be either of polycrystalline or single crystalline characteristics.