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Increased deposit purity

CELINA strives to identify novel precursors or FEBID processes that increase the purity of deposits to achieve > 90 at.% metal content. This has been achieved by different approaches as listed below. In particular, different successful purification protocols have been identified.

Pure Pt and Au deposits have been achieved in an environmental scanning electron microscope using water as a purification reagent, applied simultaneously with electron exposure both in a post-deposition process or by co-injecting water together with the precursor during deposition:

Treatment of deposits at elevated temperatures has also been successfully applied. Pure Cu phases have thus been obtained by post-deposition annealing leading to segregation of Cu from the as-deposited carbon matrix:

Purification of deposits produced from Co2(CO)8 by annealing leads to release of oxygen and thus enhances the content of cobalt to up to 85%. This way, an effective postgrowth electrical tuning was achieved:

Pure Co-FEBID nanostructures were obtained by exposure of heated samples to a H2 atmosphere
in conjunction with electron irradiation:

Electron beam induced deposition of 3D cobalt nanowires with simultaneous high metallic content (up to 85%) and small diameter has been achieved by optimization of the growth parameters without added process gas:

Pure Pt has been achieved by decomposition of solid cisplatin (Pt(NH3)2Cl2) and by purification with atomic hydrogen of deposits produced from the similar precursor Pt(CO)2Cl2. Removal of Cl is promoted by the hydrogen that, in the case of cisplatin, is delivered by the NH3 ligands:

Using novel FEBID precursors Ag-(2,2-dimethylbutanoato-κO)-(AgO2Me2Bu) and Ag(O2CC2F5) with low volatility, Ag nanostructures have been fabricated. In this process yielding deposits with up to 75% metal content, the precursor reservoir and the surface were heated:

A surprisingly low carbon content of only around 10% has been achieved by electron-beam processing of acetylacetonate precursors under UHV conditions yielding, however, partly oxidized deposits:

A non-traditional but successful approach to pure metal deposits relying on autocatalytic growth has also been established. The deposition proceeds in areas defined by prior electron-beam induced surface activation (EBISA):

The development of novel processes for deposit purification is also supported by fundamental surface science studies on the chemistry involved in such processes: