Interface engineering for scalable fabrication of high-quality, crack-free diamond films

Direct current (DC) arc plasma jet chemical vapor deposition (CVD) has emerged as an important technique for synthesizing high-quality diamond. Nevertheless, the central challenge of this technique stems from the interfacial mismatch between diamond and the substrate, which hinders the scalable synthesis of crack-free, high-quality diamond films. Here, we optimize the performance of the graphite substrate by sequentially depositing titanium (Ti) and molybdenum (Mo) layers via interfacial engineering. The Mo layer effectively resists erosion from energetic hydrogen (H) species in the DC arc plasma and promotes diamond nucleation. Simultaneously, Ti enhances adhesion at the graphite-Mo interface to improve resistance against stress during diamond deposition. Post-growth, Ti facilitates stress-induced interface fracture, allowing diamond films to self-separation. The Mo-Ti-Graphite (MTG) substrate enables the scaled production of large-area (5-inch), high-quality diamond films, achieving an impressive crack-free yield of ∼80%. Systematic experimental and theoretical analyses reveal that the MTG substrate enhances diamond quality and elucidate the mechanism of self-separation. Consequently, this approach offers an effective route to the cost-effective, scalable fabrication of high-quality, crack-free diamond films.