Replacing Ag^TSSCH₂-R with Ag^TSO ₂C-R in EGaIn-based tunneling junctions does not significantly change rates of charge transport

This paper compares rates of charge transport by tunneling across junctions with the structures Ag^TSX(CH₂)_2nCH₃ //Ga₂O₃ /EGaIn (n=1-8 and X= -SCH₂- and -O₂C-); here Ag^TS is template-stripped silver, and EGaIn is the eutectic alloy of gallium and indium. Its objective was to compare the tunneling decay coefficient (β, Å^-1) and the injection current (J₀, A cm^-2) of the junctions comprising SAMs of n-alkanethiolates and n-alkanoates. Replacing Ag^TSSCH₂-R with Ag^TSO₂C-R (R=alkyl chains) had no significant influence on J₀ (ca. 3×10³ A cm^-2) or β (0.75-0.79 Å^-1) - an indication that such changes (both structural and electronic) in the Ag^TSXR interface do not influence the rate of charge transport. A comparison of junctions comprising oligo(phenylene)carboxylates and n-alkanoates showed, as expected, that β for aliphatic (0.79 Å^-1) and aromatic (0.60 Å^-1) SAMs differed significantly. Either way: For junctions comprising thiolate- and carboxylate-anchored self-assembled monolayers (SAMs) the role of the metal-SAM interface in charge transport by tunneling was investigated and the charge-transport rates were measured. The data suggest that Ag-SAM interfaces having either a thiolate or carboxylate anchoring group may be directly comparable.