Electron-Induced Decomposition of Different Silver(I) Complexes: Implications for the Design of Precursors for Focused Electron Beam Induced Deposition

Abstract

Focused electron beam induced deposition (FEBID) is a versatile tool to produce nanostructures through electron-induced decomposition of metal-containing precursor molecules. However, the metal content of the resulting materials is often low. Using different Ag(I) complexes, this study shows that the precursor performance depends critically on the molecular structure. This includes Ag(I) 2,2-dimethylbutanoate, which yields high Ag contents in FEBID, as well as similar aliphatic Ag(I) carboxylates, aromatic Ag(I) benzoate, and the acetylide Ag(I) 3,3-dimethylbutynyl. The compounds were sublimated on inert surfaces and their electron-induced decomposition was monitored by electron-stimulated desorption (ESD) experiments in ultrahigh vacuum and by reflection−absorption infrared spectroscopy (RAIRS). The results reveal that Ag(I) carboxylates with aliphatic side chains are particularly favourable for FEBID. Following electron impact ionization, they fragment by loss of volatile CO2. The remaining alkyl radical converts to a stable and equally volatile alkene. The lower decomposition efficiency of Ag(I) benzoate and Ag(I) 3,3-dimethylbutynyl is explained by calculated average local ionization energies (ALIE) which reveal that ionization from the unsaturated carbon units competes with ionization from the coordinate bond to Ag. This can stabilise the ionized complex with respect to fragmentation. This insight provides guidance with respect to the design of novel FEBID precursors.

In Situ Time-of-Flight Mass Spectrometry of Ionic Fragments Induced by Focused Electron Beam Irradiation: Investigation of Electron Driven Surface Chemistry inside an SEM under High Vacuum

“…What can be noted is the absence of CO 2 + fragments in spectra of both carboxylates. This fragment was observed in recent electron-induced mass spectrometry (EI-MS) studies of irradiated layers of non-fluorinated silver carboxylates in UHV [ 86 ]. The lack of this fragment may indicate different electron-induced dissociation pathways for fluorinated and non-fluorinated silver carboxylates, thus possibly explaining the difference in metal content obtained in FEBID by using these group of precursors [ 74 , 87 ].…”

Liquid injection field desorption/ionization as a powerful tool to characterize volatile, labile, and reactive metal–organic complexes

“…In fact, at m/z 496, the EI mass spectrum of the mixture does just exhibit a M species are easily reduced to metallic silver(0) upon contact with electrons, as usually experienced in the focused beam electron-induced deposition (FEBID) of silver nanostructures using common scanning electron microscopy (SEM) imaging tools. 31 The affinity toward reduction after electron exposure and bombardment might be another point to consider for these types of Ag(I) species. A similar Ag(I) species bearing an anionic 1,1,1,2,2,3,3-hepta-fluoro-7,7-dimethylocatne-4,6-dione (fod) backbone in [Ag(NHC)(fod)], which features a considerably enhanced window between the temperature of evaporation and decomposition, also only features an M +• peak with a low rel.…”

Area‐Selective Chemical Vapor Deposition of Gold by Electron Beam Seeding

“…[33,34] To achieve pure 3D gold structures, additional oxidizing agents must be used in combination with elaborate shape optimization for effective purification. [35][36][37] The key question is whether this presents a fundamental constraint, or whether thermal assistance at low electron fluxes, as in the case of silver deposition, [38,39] can result in pure yet still selective metal deposition. In this scenario, the clean surface of the gold seed could even be autocatalytically active.…”