Diamond formation mechanism in chemical vapor deposition

Abstract

Significance Artificial diamond plays a vital role in the manufacturing industry, jewelry, and future photoelectronic devices, but it is a key challenge to prepare the required large-area diamonds. A distinctive way to solve this problem possibly hides in the undiscovered formation mechanism of thermodynamically metastable diamond compared to graphite in low-pressure chemical vapor deposition. We design a series of short-term growth on the margins of cauliflower-like nanocrystalline diamond particles and find that diamond is formed by the transformation from graphite, not by the piling up of sp 3 carbon. Atomically dispersed Ta atoms let the transition spontaneously occur. This subverts the general knowledge and supplies a way to prepare large-area diamonds based on large-sized graphite under normal pressure.