Controlled synthesis and mechanistic study of B, N and Si multi-doped diamond films using liquid carbon source precursors via HFCVD method

This study investigates the synthesis of B, N, and Si multi-doped diamond films using liquid carbon source precursors via the hot filament chemical vapor deposition (HFCVD) method, aiming to meet the performance requirements of diamond films for diverse applications, which possess high mechanical, electrical, and other properties. Density functional theory (DFT) calculations were employed to analyze the decomposition and adsorption processes of different precursor molecules, including trimethyl borate, urea, and tetraethyl orthosilicate, on the diamond surface. By examining the activation energy barriers and chemical adsorption energies under single doping, co-doping, and multi-doping conditions, the study elucidates the synthesis mechanisms of doped diamond films, and the interaction between different liquid precursor molecules in the synthesis of doped diamond films are explained. Experimental validation was conducted to evaluate the doping efficiency, uniformity, and element-specific interactions in the films. Secondary ion mass spectrometry (SIMS) results revealed variations in doping uniformity along the film depth and highlighted the synergistic and antagonistic effects of the dopants under single, co-doping, and multi-doping conditions. The findings demonstrate that liquid carbon source precursors provide a controlled approach for synthesizing multi-doped diamond films, with potential to improve their structural and functional performance across various technological applications.