DISPERSION LIQUID PROPERTIES FOR EFFICIENT SEEDING IN CVD DIAMOND NUCLEATION ENHANCEMENT

We investigated diamond seeding as an efficient method of enhancing th e 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 d ispersion liquids on seeding. We identified five key liquid properties for efficient seeding: zero or low dipole moment, low density, high v apor pressure, low surface tension and low viscosity. n-Hexane and n-p entane are the most suitable liquids, and yield seeding at the limit o f the powder grit. We also observed the phenomenon of chemical consoli dation of diamond particles onto silicon substrates during the initial growth stages. This consolidation ensures film adherence comparable w ith that obtained by other methods of nucleation enhancement.