Synthesis of a Large Diamond Crystal with a Smooth (100) Facet at its Top Through MPCVD

A large diamond crystal up to 500 µm in diameter with a smooth (100) facet at its top has been synthesized on Mo substrate through microwave plasma chemical vapor deposi- tion (MPCVD). Its morphology and quality were characterized by scanning electron microscopy (SEM), and the growth mechanism was roughly illustrated from both macroscopic and microscopic viewpoints. It was found that morphological instabilities are a major factor resulting in synthesis of large diamond crystals, moreover, high microwave power density (MPD), high CH 4 concentra- tions, high pressure, high substrate surface temperature and the addition of a small amount of O 2 were also necessary for the synthesis of large diamond crystals.