Focused electron beam induced deposition (FEBID) is a flexible direct-writing method of 2D and 3D metallic nanostructures, which can be easily extended to produce mixed (alloy) metallic nanostructures with tunable superior magnetic and conductive features. Alloy nanostructures can be prepared through simultaneous use of different organometallic precursor gases in FEBID. However, spontaneous dissociation of different precursors results in a challenge for obtaining precise control over the composition of reproducible deposits. So, this requires better understanding of EBID mechanism including bond breaking process and interactions between all the parties in order to establish design strategies for FEBID specific precursors providing with an exact control of nanostructure composition for high metal yield. We have developed an ultrahigh vacuum (UHV) surface science approach to study electron interactions with adsorbed EBID precursor molecules and understand the mechanistic steps of EBID at molecular level. These surface studies for adsorbed precursor is also compared to gas phase studies for volatile species desorbed from the precursor film as a result of electron irradiation. We have studied with a novel organo-bimetallic precursor, C5H5Fe(CO)2Mn(CO)5 to investigate the fate of different ligands, -CO and -C5H5, decomposing as volatile species pumped away or contamination incorporating into the deposit during EBID. Furthermore, the impact of different metal centers on the behavior of the same ligand have been simultaneously evaluated since C5H5Fe(CO)2Mn(CO)5 precursor consists of Fe and Mn metal centers in the same coordination sphere. This bimetallic precursor also provided with the opportunity to explore the response of metal centers to the same electron irradiation. Under electron irradiation, all of the CO groups attached to Fe center leave the deposit but Mn center lost only one CO ligand. In addition, as shown in our previous work, -C5H5 ligand is a poor leaving group which is incorporated into the deposit and this prevents Fe center to oxidize, whereas Mn center is oxidized. However, electron beam stimulated Fe oxidation takes place only in the presence of H2O molecules. Finally, the chemical composition of C5H5Fe(CO)2Mn(CO)5 deposit reflects the same Fe:Mn atom ratio (1:1) of the precursor molecule. Novel organo-bimetallic (heteronuclear) precursors can offer nanostructures with well-defined metal ratio for tunable conductive and magnetic properties.

Electron induced surface reactions of C5H5Fe(CO)2Mn(CO)5: Metal center impact on the behavior of organic ligands

254th National Meeting (2017)

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