A Chemically-Responsive Nanojunction within a Silver Nanowire

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• 作者：Wendong Xing ; Jun Hu ; Sheng-Chin Kung ; Keith C. Donavan ; Wenbo Yan ; Ruqian Wu ; Reginald M. Penner
• 刊名：Nano Letters
• 出版年：2012
• 出版时间：March 14, 2012
• 年：2012
• 卷：12
• 期：3
• 页码：1729-1735
• 全文大小：499K
• 年卷期：v.12,no.3(March 14, 2012)
• ISSN：1530-6992

文摘

The formation of a nanometer-scale chemically responsive junction (CRJ) within a silver nanowire is described. A silver nanowire was first prepared on glass using the lithographically patterned nanowire electrodeposition method. A 1鈥? nm gap was formed in this wire by electromigration. Finally, this gap was reconnected by applying a 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 change that was as large as 螖R/R₀ = (+)138% in 7% NH₃ and observable down to 500 ppm NH₃. Exposure to water vapor produced a weaker resistance increase of 螖R/R_0,H2O = (+)10鈥?5% (for 2.3% water) while nitrogen dioxide (NO₂) exposure induced a stronger concentration-normalized resistance decrease of 螖R/R_0,NO2 = (鈭?10鈥?5% (for 500 ppm NO₂). The proposed mechanism of the resistance response for a CRJ, supported by temperature-dependent measurements of the conductivity for CRJs and density functional theory calculations, is that semiconducting p-type Ag_xO is formed within the CRJ and the binding of molecules to this Ag_xO modulates its electrical resistance.

Keywords:

Sensor; ammonia; nitrogen dioxide; electrodeposition; oxide; electromigration