Versatile direct-writing of dopants in a solid state host through recoil implantation

Abstract

Modifying material properties at the nanoscale is crucially important for devices in nano-electronics, nanophotonics and quantum information. Optically active defects in wide band gap materials, for instance, are critical constituents for the realisation of quantum technologies. Here, we demonstrate the use of recoil implantation, a method exploiting momentum transfer from accelerated ions, for versatile and mask-free material doping. As a proof of concept, we direct-write arrays of optically active defects into diamond via momentum transfer from a Xe+ focused ion beam (FIB) to thin films of the group IV dopants pre-deposited onto a diamond surface. We further demonstrate the flexibility of the technique, by implanting rare earth ions into the core of a single mode fibre. We conclusively show that the presented technique yields ultra-shallow dopant profiles localised to the top few nanometres of the target surface, and use it to achieve sub-50 nm positional accuracy. The method is applicable to non-planar substrates with complex geometries, and it is suitable for applications such as electronic and magnetic doping of atomically-thin materials and engineering of near-surface states of semiconductor devices.

Low-Temperature Spectroscopic Investigation of Lead-Vacancy Centers in Diamond Fabricated by High-Pressure and High-Temperature Treatment

“…𝜏 yields an estimation of the excited state lifetime of a florescent structure at a low excitation power 47 . The excited state lifetime of the observed single PbV center was estimated to be ~3.7 ns, which is consistent with another experimental result 31 . The fluorescence intensity is measured as a function of the excitation laser power, as shown in Fig.…”

“…To date, several studies have been reported for the fabrication of lead-vacancy (PbV) centers in diamond. However, the optical transition energy of the PbV center has not been determined consistently: values have been reported at ∼550 − or ∼520 nm …”

Recoil implantation using gas-phase precursor molecules

“…This is higher than but comparable to our previous work using solid metallic precursors, where a fluence of less than 1 x 10 12 cm -2 was needed to observe patterned regions of the same size. 19 The values obtained in this study are higher because of the lower concentration of adsorbates on the surface compared to a solid thin film and the ability for the gaseous precursors to desorb or diffuse unlike the solid metallic precursor. This naturally results in a lower probability of the recoil process, and therefore requires higher total fluence values.…”

“…13, Further to the above, we have recently demonstrated the use of recoil implantation [16][17][18] in combination with a standard FIB system. 19 In that work, momentum transfer from inert ions in a nano-scale beam to a thin film was used for implantation of the film constituents. This was demonstrated by implanting group IV elements into a bulk diamond substrate, which resulted in the creation of group IV color centers.…”

“…The recoil implantation technique provides control over dopant density using the ion beam irradiation and scanning parameters, and enables ultra-shallow implantation, with the majority of dopants located within the first 2 nm of the surface. 19 Hence, this technique allows for a wide range of implant species using a single ion source, as well as beam-directed control over the location and density of the dopants. However, it is limited to the use of solid-state precursors that can be deposited in the form of a removable film.…”