Ion implantation for deterministic single atom devices

Abstract

Abstract:We demonstrate a capability of deterministic doping at the single atom level using a combination of direct write focused ion beam and solid-state ion detectors. The focused ion beam system can position a single ion to within 35 nm of a targeted location and the detection system is sensitive to single low energy heavy ions. This platform can be used to deterministically fabricate single atom devices in materials where the nanostructure and ion detectors can be integrated, including donor-based qubits in Si and color centers in diamond.Deterministic placement of single atoms is a key capability for fabrication of nanometer scale and single atom solid-state devices in a range of material systems including Si, diamond, and III-V compounds. Examples of Si-based devices include: donors coupled to quantum dots [1] for charge [2], electron [3,4], and nuclear spin [5,6] qubits (quantum bits) and acceptors coupled to silicon cavities to create phononic qubits [7]. Single color (defect) centers in diamond have a range of applications including metrology [8], quantum computing using nitrogen-vacancy (NV) centers [9] and coupling silicon-vacancy (SiV) centers to photonic cavities for cavity QED experiments [9,10]. In III-V materials, deterministic seeding of nucleation sites for controlling the quantum dot growth locations [11] has many potential applications including the development of single photon sources [12]. In many applications, placement of single ions within small volumes is critical. Ion implantation has been widely applied in the semiconductor industry for introducing dopants with a nominal depth and dose by varying the implant energy and the exposure time, respectively. The key challenges to extending this technique down to single atom control are the precise control over the atom's position and the implantation of one and only one atom. Techniques include in-situ ion detection using PIN diode detectors [13][14][15] and FinFETs [16,17] and detection of secondary electrons [18].We present a "top down" ion implantation approach to deterministic single atom device fabrication in Si and in other material systems suitable for ion detection including diamond [19] and GaAs [20]. This requires the ability to place the implanted ions with high positioning precision and deterministic control over the number of ions implanted. We use the nanoImplanter (nI) at Sandia National Labs (SNL), which is a direct-write focused ion beam platform to control the positioning of the implanted ion and in-situ solid-state detectors for single ion detection. We demonstrate single ion targeting to less than 35 nm allowing for deterministic single ion implantation. The combination of focused ion beams, direct write lithography, fast beam blanking and chopping, ion mass selectivity, in-situ detection and electrical probing are key features that enable rapid prototyping, customized implantation and high throughput fabrication of deterministic single atom devices. As a test of our "top-down" ion implantation and detection capability we...

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