Dispersion liquid properties for efficient seeding in CVD diamond nucleation enhancement

We investigated diamond seeding as an efficient method of enhancing the nucleation density in chemical vapor deposition (CVD) diamond growth. We prepared substrates by ultrasonification for a short time in a 0.25 mu m diamond powder suspension and studied the effects of several dispersion liquids on seeding. We identified five key liquid properties for efficient seeding: zero or low dipole moment, low density, high vapor pressure, low surface tension and low viscosity. n-Hexane and n-pentane are the most suitable liquids, and yield seeding at the limit of the powder grit. We also observed the phenomenon of chemical consolidation of diamond particles onto silicon substrates during the initial growth stages. This consolidation ensures film adherence comparable with that obtained by other methods of nucleation enhancement.