Generation of isolated Nitrogen-vacancy centers in diamond by ion implantation

The project’s main ambition is the development of a deterministic single ion implantation method at the tandem accelerator of the Microanalytical centre at the Jozef Stefan Institute to greatly advance the fields of quantum computing and materials science. Ion implantation is a well recognized technique in the semiconductor industry and research, and a very promising method enabling ground-breaking research in novel quantum technologies, including quantum computing and quantum information processing. Here, the scalability of produced basic units of quantum information (qubits) is the main limitation of the state of the art, which is currently mostly based on ultra-low temperatures. The proposed approach focuses on producing a new basis for storing qubits in solid matter at room temperatures. Candidate techniques for ion implantation are based on either phosphorous donors in silicon, or on nitrogen-vacancy (NV) centres in diamond. Both show much promise, although many difficult challenges remain. The main requirement for successful qubit production via ion implantation is determinism - a specified number of single ions should be implanted into predetermined positions. This requires high precision of the beam, as well as tightly controlled ion beam intensity. Such criteria can be met by employing the 2 MV tandem accelerator at JSI, where ions of most of the stable elements within the periodic system can be accelerated to energy spectra in the keV and MeV ranges. Ions can be focused below 200 nm in a controllable manner, combining slit apertures and magnetic quadrupole triplet lenses. Afterwards, a focused ultra-low current beam can be rastered across the area of 2 x 2 mm2 or smaller, allowing multiple ions to be implanted on various pre-determined positions without changing the experimental conditions. In our project we aim to generate NV centres in diamond by using N ions within MeV range. Although implantation of phosphorous in Silicon is a competitive method, the success of such approach is limited by the isotopic purity of 28 Si, and the supply of pure Silicon is very low. Our goal is to successfully create a stable grid of NV centres with – on average - one nitrogen atom in each point defect, which may afterwards be confirmed with high precision imaging methods, such as SEM or TEM. Additionally, we will research the possibilities for improving the determinism of ion implantation, hopefully allowing significant advances in material science and quantum computing.