Heteroepitaxial Growth of Single-Crystal Diamond on Amorphous Carbon under High Pressure and High Temperature

Abstract

High-pressure and high-temperature (HPHT) heteroepitaxy enables diamond growth with dislocation densities approaching those of homoepitaxial crystals, yet the role of the amorphous carbon interlayer at the heterointerface remains poorly understood. Here, we investigate the nucleation and growth behavior of diamond on amorphous glassy carbon under HPHT conditions. Diamond nucleation on amorphous glassy carbon is achieved at 5.5 GPa by tuning nucleation temperature and duration, followed by single-crystal growth on the amorphous substrate. The resulting heteroepitaxial diamonds exhibit RC full widths at half maximum of 0.0037°−0.0142°, corresponding to dislocation densities as low as 10⁵−10⁶ cm⁻², comparable to conventional HPHT single crystals. Finite element simulations reveal that the confined growth structure reduces carbon concentration during the initial growth stage, suppressing random multi-site nucleation and polycrystalline competition, thereby enabling continuous growth from limited nucleation sites. In addition, stable growth on large-diameter glassy carbon seeds requires increased pit depth to provide sufficient relaxation time. These results clarify the role of amorphous carbon in HPHT heteroepitaxy and provide a feasible route for expanding seed selection in diamond growth.