STEM-EELS/EDS Identification and Manipulation of Color Centers in Nanodiamond

Single-photon-emitting color centers in nanodiamonds are studied extensively for their application in quantum systems. In addition to strong single-photon photoluminescence from the color centers, diamond has many advantages such as chemical inertness, mechanical hardness, and zero nuclear spin. Nitrogen-vacancy (NV) centers in nanodiamonds are a potential architecture for single-atom quantum systems. However, unambiguous identification of a single NV center in a nanodiamond is challenging. Computational work has predicted that the NV center produces a peak at 282.4 eV near the carbon K-edge in electron energy loss spectroscopy (EELS). Here, we perform simultaneous EELS and energy dispersive x-ray spectroscopy (EDS) spectrum imaging in an aberration-corrected scanning transmission electron microscope (STEM) to identify single NV centers by identifying pixels that contain both the EELS 282.4 eV peak and the EDS nitrogen signal at 0.39 keV.<br/>Atomic-scale identification of NV centers is an important first step toward single-atom quantum device fabrication. We further demonstrate that the focused probe of the STEM can be used to reposition N and NV centers in the diamonds. By scanning the electron beam over a single nanodiamond for an extended period of time, we demonstrate the ability to: 1. corral N atoms into one region of the nanodiamond; and 2. redistribute the N throughout the nanodiamond. This is a significant step toward single-defect manipulation in nanodiamond, and density functional theory (DFT) calculations will help elucidate the exact mechanism of this atomic-scale manipulation.