Maskless single ion implantion with nanometer spatial resolution for scalable quantum photonic devices
In various materials single ion implantations have been proven to serve as solid-state quantum bit and quantum photonics. In search of the ideal qubit researchers aiming for bright narrowband emissions and availability of optical read out and manipulation of spin states. Therefore researchers explore the benefits of ion specie and substrate combinations to improve properties such as Debye Waller factor, long spin coherence times or ground state splitting.
Two recent publications from Zheng Liu at al. (https://pubs.acs.org/doi/abs/10.1021/acsphotonics.7b00230) and Igor Aharonivich at al. (https://iopscience.iop.org/article/10.1088/1367-2630/aaf2ac) show the potential of Raiths focused ion beam systems VELION to serve as a maskless vacancy maker with high spatial resolution.
Mr Liu and colleges have studied the effect of implanted Si2+ ions into silicon carbide in terms of optical and spin properties. The photostabiliy was proven to be stable. No blinking or bleaching was observable also the count was stable, which is important for quantum information applications. The average number of defects on a spot where 40 ions were implanted was evaluated to be 1.56 with 19 single vacancies out of 50 spot. This means a single vacancy creation efficiency of about 38% proving an efficient generation of single photon surces, which is necessary for coupling with photonic structures.
“This method offers new possibilities for realizing phontonic applications where there arises a need to place a single of few Silicon vacancy defect centers within a nanometerscale region”, the author stated.
Mr. Aharonovich and colleges found great benefits of this approach by using Germanium ions and diamond substrate for photonic structures, too. They proved the emitters to be germanium vacancies by photoluminescence spectrum studies at room- and cryogenic temperatures and optically detected magnetic resonance. Here the spectrum shows four peaks around 600nm, corresponding to ground and exited states split by spin-orbit coupling. As for Si ions generated defects, here the photostability was found to be good, too. The probability of creating single emitters was found to be 53% by applying a dose of 200 ions per spot. With higher doses the number of emitters rises which is “extremely helpful in efficient and deterministic fabrication of single Germanium vacancy centers at tens of nanometer spatial precision” Mr. Aharonivich pointed out.
Both papers show the new possibility for the realization to place single or few vacancy centers with position accuracy in the nanometer regime for photonic applications.