Evidence for Primal sp2 Defects at the Diamond Surface: Candidates for Electron Trapping and Noise Sources

Abstract Many advanced applications of diamond materials are now being limited by unknown surface defects, including in the fields of high power/frequency electronics and quantum computing and quantum sensing. Of acute interest to diamond researchers worldwide is the loss of quantum coherence in near‐surface nitrogen‐vacancy (NV) centers and the generation of associated magnetic noise at the diamond surface. Here for the first time is presented the observation of a family of primal diamond surface defects, which is suggested as the leading cause of band‐bending and Fermi‐pinning phenomena in diamond devices. A combination of density functional theory and synchrotron‐based X‐ray absorption spectroscopy is used to show that these defects introduce low‐lying electronic trap states. The effect of these states is modeled on band‐bending into the diamond bulk and it is shown that the properties of the important NV defect centers are affected by these defects. Due to the paramount importance of near‐surface NV center properties in a growing number of fields, the density of these defects is further quantified at the surface of a variety of differently‐treated device surfaces, consistent with best‐practice processing techniques in the literature. The identification and characterization of these defects has wide‐ranging implications for diamond devices across many fields.