Growth of Single Crystalline Diamond and Surface Control

Single spins in diamond, like nitrogen-vacancy-centers (NV), have unique properties making them candidates for various applications. Their spin can be manipulated and optically read out at room temperature, so they can be used for atomic imaging, magnetometry, spin sensing or qubits in quantum information protocols. The controlled creation of such desired diamond defects still remains a challenge. Besides the ion implantation, the diamond growth using Plasma-Enhanced-Chemical-Vapor-Deposition (PECVD) is the state of the art technique to produce single spin defects in diamond. With our PECVD reactor (schematic picture to the right) we are able to grow pure diamond layers (no impurities in the lattice) and nitrogen doped layers (NVs are created at a desired depth with nm precision). Furthermore it is important to control the isotopical purity in the crystal (12C/13C ratio) as it depicts the spin bath for the created color centers.

By nitrogen delta doping at the last step of a PECVD growth process we are able to produce shallow NV centers a few nanometers below the surface which can be used for sensing applications. By controlling the diamond surface termination (H,O,F,Cl) we can control the charge state of the NVs. Exemplary there is shown the schematic picture of a CVD grown diamond with delta doped layers on the left side and the corresponding confocal image on the right side where NV centers appear as bright spots. The fluorescence map nicely shows the boarderline between the type Ib diamond substrate, the type IIa and the delta doped grown diamond layers.

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