Seed-free growth of diamond patterns on silicon predefined by femtosecond laser direct writing

Seed-free growth of diamond patterns on Si surfaces was realized by surface patterning via femtosecond laser direct writing followed by laser-assisted combustion synthesis in open air. Prepatterned Si surfaces provide active nucleation sites for diamond growth. The dimension and shape of the diamond patterns can be precisely controlled at micrometer scales. Field-enhanced thermionic emission current was measured to monitor diamond nucleation and growth process in real time. The diamond nucleation density and quality depend strongly on the surface roughness of the prepatterned Si patterns. A higher surface roughness leads to more nucleation sites and higher nucleation density. However, high local temperature at peaks due to a large exposed surface to the flame on an excessively rough surface degrades the diamond quality. The easy fabrication of diamond patterns on nondiamond surfaces suggests potential applications such as cutting tools, protective coatings, heat sinks, etc.