Optical tuning of the diamond Fermi level measured by correlated scanning probe microscopy and quantum defect spectroscopy

Precise control of diamond's surface termination is crucial for electronic devices and the charge stability of shallow, implanted color centers for quantum devices, such as the nitrogen-vacancy (NV) and silicon-vacancy (SiV) center. Previously, such surface control relied on aggressive treatments, such as annealing, plasma exposure, or strong acids, but here the authors demonstrate a novel technique utilizing a laser under ambient conditions. This technique is demonstrated on NV and SiV centers, with optical spatial resolution and continuous optical feedback. They are able to image the change in the diamond's work function through Kelvin probe force microscopy, and determine the mechanism as laser-assisted oxidation.