1 research outputs found
Electrical Resistance of Ag<sup>TS</sup>–S(CH<sub>2</sub>)<sub><i>n</i>−1</sub>CH<sub>3</sub>//Ga<sub>2</sub>O<sub>3</sub>/EGaIn Tunneling Junctions
Tunneling junctions having the structure Ag<sup>TS</sup>–SÂ(CH<sub>2</sub>)<sub><i>n</i>−1</sub>CH<sub>3</sub>//Ga<sub>2</sub>O<sub>3</sub>/EGaIn allow physical–organic
studies
of charge transport across self-assembled monolayers (SAMs). In ambient
conditions, the surface of the liquid metal electrode (EGaIn, 75.5
wt % Ga, 24.5 wt % In, mp 15.7 °C) oxidizes and adsorbs―like
other high-energy surfaces―adventitious contaminants. The interface
between the EGaIn and the SAM thus includes a film of metal oxide,
and probably also organic material adsorbed on this film; this interface
will influence the properties and operation of the junctions. A combination
of structural, chemical, and electrical characterizations leads to
four conclusions about Ag<sup>TS</sup>–SÂ(CH<sub>2</sub>)<sub><i>n</i>−1</sub>CH<sub>3</sub>//Ga<sub>2</sub>O<sub>3</sub>/EGaIn junctions. (i) The oxide is ∼0.7 nm thick on
average, is composed mostly of Ga<sub>2</sub>O<sub>3</sub>, and appears
to be self-limiting in its growth. (ii) The structure and composition
(but not necessarily the contact area) of the junctions are conserved
from junction to junction. (iii) The transport of charge through the
junctions is dominated by the alkanethiolate SAM and not by the oxide
or by the contaminants. (iv) The interface between the oxide and the
eutectic alloy is rough at the micrometer scale