Tunable morphology-quality synergy in (111) single crystal diamond via coupled process control

This study employs microwave plasma chemical vapor deposition (MPCVD) to systematically investigate the synergistic effects of deposition temperature (793-925 °C) and methane concentration (0.5-2.0%) on the homoepitaxial growth of (111)-oriented single-crystal diamond. Through comprehensive characterization, the intrinsic relationships between process parameters and crystal surface morphology, crystalline quality, and internal stress were revealed. Results indicate that the growth rate increases significantly with rising temperature and methane concentration, reaching a maximum of 1.73 µm h^-1. Under low temperature and low methane conditions, cracks and etch pits along the <110> direction were observed. These morphological features transitioned into wavy and eventually straight step-flow structures as process parameters were optimized, while sharp step structures emerged at high methane concentrations. XRD and Raman analyses demonstrated that samples grown in the medium-temperature range (861-875 °C) exhibited the best crystalline quality and the lowest stress, attributed to a balance between atomic migration capability and stress relaxation, which is crucial for high-quality epitaxial growth. This work provides key process windows and theoretical support for the controlled growth of (111) single-crystal diamond for electronic device applications.