Rapid and Highly Compact Purification for Focused Electron Beam Induced Deposits: A Low Temperature Approach Using Electron Stimulated H₂O Reactions

Abstract

Focused electron beam induced deposition (FEBID) is an important synthesis method as it is an extremely flexible tool for fabricating functional (3D) structures with nanometer spatial resolution. However, FEBID has historically suffered from carbon impurities up to 90 at %, which significantly limits the intended functionalities. In this study we demonstrate that MeCpPtIVMe3 deposits can be fully purified by an electron-beam assisted approach using H2O vapor at room temperature, which eliminates sample and/or gas heating and complicated gas delivery systems, respectively. We demonstrate that local pressures of 10 Pa results in an electron-limited regime, thus enabling high purification rates of better than 5 min·nA–1·μm–2 (30 C·cm–2) for initially 150 nm thick deposits. Furthermore, TEM measurements suggest the purification process for the highly compact deposits occurs via a bottom-up process.

Plasmonic gold helices for the visible range fabricated by oxygen plasma purification of electron beam induced deposits

“…In contrast to the treatment of platinum deposition in water vapor with a higher permeability coefficient and a lower chemisorption a bottom-up purification has been noted. 29 The observed out-to inside purification in this study is a first hint that the permeability coefficient of the radicals is comparably small in the case of oxygen plasma applied for gold-containing deposits.…”

“…Therefore, the quantification presented here relies on peaks ratios of Au:C after subtracting the background instead of absolute amounts. 29 substrate proves that the signal originates from gold material only. However, as expected even the pure gold sample exhibits a distinct carbon signal resulting from the residual gases inside the chamber.…”

Purification of Au EBID structures by electron beam post-irradiation under oxygen flux at room temperature

“…In the recent past, several other post deposition purification protocols have been reported. For carbon-rich Pt EBID structures, an electron beam assisted oxygen purification at oxygen temperatures as low as 50°C [13] and post-growth purification using electron assisted H 2 O purification [14] and electron beam assisted purification with pulsated oxygen exposure [15] have been observed to yield pure Pt structures after the post-treatment. Pt EBID structures have been reported to be purified very rapidly (laser exposure time <1 s) by pulsed laser-induced oxidation reaction [16].…”

Direct-Write Fabrication of Cellulose Nano-Structures via Focused Electron Beam Induced Nanosynthesis

“…While we have already shown before that the intermediate and desired product is cellulose, beam damage also present from the beginning renders a fraction of the exposed materials non-degradable. The assumption of a carbon-rich residue at high doses is feasible as similar processes in FEBID and dedicated studies have been shown in literature5761. The fitting model provides valuable information on the rate-constants and reaction-speeds (full summary can be found in supplement 4).…”