Atomic Focused Nitrogen Ion Beam from a Liquid-Metal Alloy Ion Source*

Focused ion beam (FIB) implantation is a popular technique in the fabrication of optically active color centers. The nanometer scale resolution of FIB implantation allows targeting of photonic structures for scalable fabrication of color centers. The nitrogen-vacancy (NV) in diamond has been shown to be an extremely sensitive magnetic field sensor and recent results have measured magnetic fields in record low volume through integration of NV with AFM tips. A scalable FIB source for localized implantation of nitrogen (N) has not yet been demonstrated but is a critical component in nanometer resolution placement of NVs for quantum applications.

We have made and characterized a FIB N source based on a AuSn liquid metal alloy ion source eutectic that will enable scalable fabrication of localized NVs. We add N to the foil, which is then released during field emission, by implanting thin AuSn foils with 200 keV N⁺⁺. We confirm inclusion of N through elastic recoil detection and release of N⁺ and N⁺⁺ ions during operation of the source using ion beam induced charge collection measurements. We will report on the source characteristics including beam current, lifetime (approximately 200 µAh), stability and spot size.

SNL is managed and operated by NTESS under DOE NNSA contract DE-NA0003525