Nitrogen control in HPHT single-crystal diamond growth for quantum applications

Diamond, the "ultimate semiconductor," outperforms conventional semiconductors like SiC/GaN in high-power applications due to its superior material properties. It also promises innovations in quantum metrology and sensing. Yet, challenges include the need for wafer-scale (>=20 mm in diameter), high-crystalline-quality, high-purity diamond substrates with a defect density below 10 cm^-2. The current"electronic" and “quantum” grade Chemical Vapor Deposition diamond substrates fall short in respect of defect densities (with a range of 10^3-7 cm^-2). In contrast, high-pressure, high-temperature (HPHT) diamond growth technology holds a significant advantage for high-crystallinity substrates. We developed an advanced BARS HPHT technology to control nitrogen purity in diamond crystals. This unique approach, distinct from those adopted worldwide, offers potential advantages in compactness, cost-effectiveness, and flexibility to adjust growth parameters. Advanced nitrogen-removal conditions during diamond growth will also allow it to reach a level comparable to or exceeding the CVD purity of the material.