Homoepitaxial diamond film growth: High purity, high crystalline quality, isotopic enrichment, and single color center formation

With optical/electronic devices of the next generation in mind, we provide a guideline for the growth of homoepitaxial diamond films that possess higher crystalline quality, higher chemical purity, and a higher carbon isotopic ratio. A custom-built microwave plasma-assisted chemical vapor deposition system was constructed to achieve these requirements. To improve both the purity and crystalline quality of homoepitaxial diamond films, an advanced growth condition was applied: higher oxygen concentration in the growth ambient. Under this growth condition for high-quality diamond, a thick diamond film of ≥30 μm was deposited reproducibly while maintaining high purity and a flat surface. Then, combining this advanced growth condition for non-doped diamond with a unique doping technique that provides parts-per-billion order doping, single-color centers of either nitrogen-vacancy or silicon-vacancy centers that show excellent properties were formed. The new idea of using these color centers as a probe for detecting tiny amounts of impurities was presented. These advanced growth and characterization techniques are expected to open up new fields of diamond research that require extremely low-impurity concentration, for use in power devices and quantum information devices.