A Chemically-ResponsiveNanojunction within a SilverNanowire.

The formation of a nanometer-scale chemically responsivejunction(CRJ) within a silver nanowire is described. A silver nanowire wasfirst prepared on glass using the lithographically patterned nanowireelectrodeposition method. A 1–5 nm gap was formed in this wireby electromigration. Finally, this gap was reconnected by applyinga voltage ramp to the nanowire resulting in the formation of a resistive,ohmic CRJ. Exposure of this CRJ-containing nanowire to ammonia (NH3) induced a rapid (<30 s) and reversible resistance changethat was as large as ΔR/R0= ()138% in 7% NH3and observable down to 500ppm NH3. Exposure to water vapor produced a weaker resistanceincrease of ΔR/R0,H2O= ()10–15% (for 2.3% water) while nitrogen dioxide (NO2) exposure induced a stronger concentration-normalized resistancedecrease of ΔR/R0,NO2= (−)10–15% (for 500 ppm NO2). The proposed mechanism of the resistance response for a CRJ, supportedby temperature-dependent measurements of the conductivity for CRJsand density functional theory calculations, is that semiconductingp-type AgxO is formed within the CRJ andthe binding of molecules to this AgxOmodulates its electrical resistance. [ABSTRACT FROM AUTHOR]