Conductance-Based Chemical Sensing in Metallic Nanowires and Metal-Semiconductor Nanostructures

Abstract

Conductance-based chemical sensing in metal-semiconductor nanostructures and all-metal nanowires of atomic dimensions is garnering increased interest. Adsorbed gas molecules can migrate to a metal-semiconductor junction, thereby shifting the magnitude of the Schottky barrier and altering electrical impedance, whereas atomic scale metal junctions can sensitively report the presence of adsorbates through their impact on ballistic electron transport.

Probing the effect of surface chemistry on the electrical properties of ultrathin gold nanowire sensors

“…This is an important feature when considering the electronic interactions between adsorbates and metals, since it implies that the driving force changing the resistance of the metal is mainly dominated by the HOMO-LUMO interaction resulting from the metal-adsorbate binding moiety. 40,41 Hence, Persson's model predicts that for sensors based on metal NWs, the resistance change is independent of the chain length or functional groups of the adsorbate that do not interact directly with the orbitals near the HOMO-LUMO gap. This effect was identied in X-ray photoelectron spectroscopy experiments, showing that the energy binding of the thiol moiety from different thiolate molecules on Au surface was the same.…”

Probing the effect of surface chemistry on the electrical properties of ultrathin gold nanowire sensors

“…This is an important feature when considering the electronic interactions between adsorbates and metals, since it implies that the driving force changing the resistance of the metal is mainly dominated by the HOMO-LUMO interaction resulting from the metal-adsorbate binding moiety. 40,41 Hence, Persson's model predicts that for sensors based on metal NWs, the resistance change is independent of the chain length or functional groups of the adsorbate that do not interact directly with the orbitals near the HOMO-LUMO gap. This effect was identied in X-ray photoelectron spectroscopy experiments, showing that the energy binding of the thiol moiety from different thiolate molecules on Au surface was the same.…”

Nanowire Sensors Using an Electrical Resonance Approach for Vapor Detection

“…Therefore, developing these sensor technologies has the potential to revolutionize science and to influence major economic, agricultural, environmental, social, and health issues. [1][2][3][4][5] In this regard, nanowirebased sensors are expected to exhibit a higher performance due to their many enhanced characteristics such as high surface-to-volume ratio, one-dimensional (1D) confinement of carriers, high sensitivity, low power consumption, and fast response. [6][7][8][9][10][11] Further, several possible next generation quantum computing and novel low energy sensing applications of 1D nanoscale systems have been proposed by predicting a significant squeezing in the quantum state of motion of nano-resonator due to an electrically induced nonlinearity.…”

“…12,13 The surfaces of nanostructured materials such as nanowires often have higher defect density due to the presence of dangling bonds or surface reconstruction, and as a result show high sensitivity to adsorption by various analytes. 3,14,15 Furthermore, there is an everincreasing interest in developing new approaches that may be used not only to enhance sensitivity, but also to impart selectivity to microscale and nanoscale sensors. [16][17][18][19][20] The microfabricated sensors such as microcantilevers often employ optical methods for signal transduction, which involves reflecting a beam of light off the free end of the resonator onto a position-sensitive detector.…”

Nanowire Chemical/Biological Sensors: Status and a Roadmap for the Future

“…[53] Metal NWs can be synthesized by chemical etching [105] or reductive cation electrodeposition. [103,107] Metal NWs can be synthesized by bulk solutionphase methods,where apolyol is used as both the solvent and reducing agent for metal cations.…”

“…2) Developing sensors that leverage junctions between NWs and electrodes.S chottky barriers [36,103,149] and swellinginduced expansion of tunneling barriers [113,122,216,240] have been introduced as important mechanisms.Amajor opportunity lies in placing responsive materials/molecules in the tunnel junction that can be chemically triggered to have resonant electronic states with the NWs.Rectifying interfaces between p-and n-NWs can also provide opportunities for amplification in analogy to gain produced by avalanche photodiodes.3 )Complex signals can be used to minimize noise,and combinations of resistive and capacitive responses need to be understood. Advances in capacitive sensing are possible by utilizing charge polarization along the length of NWs isolated by resistive junctions.S pace-charge contributions to am aterials dielectric constant are much larger than simple dipolar effects.E ffectively harnessing space-charge changes in chemical/biological sensors will involve careful positioning (orienting) of NWs,c ontrolling the electrical transport and dielectric coupling between NWs,and choice of optimal fields and frequencies.…”

Probing the effect of surface chemistry on the electrical properties of ultrathin gold nanowire sensors

“…This is an important feature when considering the electronic interactions between adsorbates and metals, since it implies that the driving force changing the resistance of the metal is mainly dominated by the HOMO-LUMO interaction resulting from the metal-adsorbate binding moiety. 40,41 Hence, Persson's model predicts that for sensors based on metal NWs, the resistance change is independent of the chain length or functional groups of the adsorbate that do not interact directly with the orbitals near the HOMO-LUMO gap. This effect was identied in X-ray photoelectron spectroscopy experiments, showing that the energy binding of the thiol moiety from different thiolate molecules on Au surface was the same.…”

Nanowire Sensors Using an Electrical Resonance Approach for Vapor Detection

“…Therefore, developing these sensor technologies has the potential to revolutionize science and to influence major economic, agricultural, environmental, social, and health issues. [1][2][3][4][5] In this regard, nanowirebased sensors are expected to exhibit a higher performance due to their many enhanced characteristics such as high surface-to-volume ratio, one-dimensional (1D) confinement of carriers, high sensitivity, low power consumption, and fast response. [6][7][8][9][10][11] Further, several possible next generation quantum computing and novel low energy sensing applications of 1D nanoscale systems have been proposed by predicting a significant squeezing in the quantum state of motion of nano-resonator due to an electrically induced nonlinearity.…”

“…12,13 The surfaces of nanostructured materials such as nanowires often have higher defect density due to the presence of dangling bonds or surface reconstruction, and as a result show high sensitivity to adsorption by various analytes. 3,14,15 Furthermore, there is an everincreasing interest in developing new approaches that may be used not only to enhance sensitivity, but also to impart selectivity to microscale and nanoscale sensors. [16][17][18][19][20] The microfabricated sensors such as microcantilevers often employ optical methods for signal transduction, which involves reflecting a beam of light off the free end of the resonator onto a position-sensitive detector.…”

Nanowire Chemical/Biological Sensors: Status and a Roadmap for the Future

“…[53] Metal NWs can be synthesized by chemical etching [105] or reductive cation electrodeposition. [103,107] Metal NWs can be synthesized by bulk solutionphase methods,where apolyol is used as both the solvent and reducing agent for metal cations.…”

“…2) Developing sensors that leverage junctions between NWs and electrodes.S chottky barriers [36,103,149] and swellinginduced expansion of tunneling barriers [113,122,216,240] have been introduced as important mechanisms.Amajor opportunity lies in placing responsive materials/molecules in the tunnel junction that can be chemically triggered to have resonant electronic states with the NWs.Rectifying interfaces between p-and n-NWs can also provide opportunities for amplification in analogy to gain produced by avalanche photodiodes.3 )Complex signals can be used to minimize noise,and combinations of resistive and capacitive responses need to be understood. Advances in capacitive sensing are possible by utilizing charge polarization along the length of NWs isolated by resistive junctions.S pace-charge contributions to am aterials dielectric constant are much larger than simple dipolar effects.E ffectively harnessing space-charge changes in chemical/biological sensors will involve careful positioning (orienting) of NWs,c ontrolling the electrical transport and dielectric coupling between NWs,and choice of optimal fields and frequencies.…”

Probing the effect of surface chemistry on the electrical properties of ultrathin gold nanowire sensors

“…This is an important feature when considering the electronic interactions between adsorbates and metals, since it implies that the driving force changing the resistance of the metal is mainly dominated by the HOMO-LUMO interaction resulting from the metal-adsorbate binding moiety. 40,41 Hence, Persson's model predicts that for sensors based on metal NWs, the resistance change is independent of the chain length or functional groups of the adsorbate that do not interact directly with the orbitals near the HOMO-LUMO gap. This effect was identied in X-ray photoelectron spectroscopy experiments, showing that the energy binding of the thiol moiety from different thiolate molecules on Au surface was the same.…”

Nanowire Sensors Using an Electrical Resonance Approach for Vapor Detection

“…Therefore, developing these sensor technologies has the potential to revolutionize science and to influence major economic, agricultural, environmental, social, and health issues. [1][2][3][4][5] In this regard, nanowirebased sensors are expected to exhibit a higher performance due to their many enhanced characteristics such as high surface-to-volume ratio, one-dimensional (1D) confinement of carriers, high sensitivity, low power consumption, and fast response. [6][7][8][9][10][11] Further, several possible next generation quantum computing and novel low energy sensing applications of 1D nanoscale systems have been proposed by predicting a significant squeezing in the quantum state of motion of nano-resonator due to an electrically induced nonlinearity.…”

“…12,13 The surfaces of nanostructured materials such as nanowires often have higher defect density due to the presence of dangling bonds or surface reconstruction, and as a result show high sensitivity to adsorption by various analytes. 3,14,15 Furthermore, there is an everincreasing interest in developing new approaches that may be used not only to enhance sensitivity, but also to impart selectivity to microscale and nanoscale sensors. [16][17][18][19][20] The microfabricated sensors such as microcantilevers often employ optical methods for signal transduction, which involves reflecting a beam of light off the free end of the resonator onto a position-sensitive detector.…”

Nanowire Chemical/Biological Sensors: Status and a Roadmap for the Future

“…[53] Metal NWs can be synthesized by chemical etching [105] or reductive cation electrodeposition. [103,107] Metal NWs can be synthesized by bulk solutionphase methods,where apolyol is used as both the solvent and reducing agent for metal cations.…”

“…2) Developing sensors that leverage junctions between NWs and electrodes.S chottky barriers [36,103,149] and swellinginduced expansion of tunneling barriers [113,122,216,240] have been introduced as important mechanisms.Amajor opportunity lies in placing responsive materials/molecules in the tunnel junction that can be chemically triggered to have resonant electronic states with the NWs.Rectifying interfaces between p-and n-NWs can also provide opportunities for amplification in analogy to gain produced by avalanche photodiodes.3 )Complex signals can be used to minimize noise,and combinations of resistive and capacitive responses need to be understood. Advances in capacitive sensing are possible by utilizing charge polarization along the length of NWs isolated by resistive junctions.S pace-charge contributions to am aterials dielectric constant are much larger than simple dipolar effects.E ffectively harnessing space-charge changes in chemical/biological sensors will involve careful positioning (orienting) of NWs,c ontrolling the electrical transport and dielectric coupling between NWs,and choice of optimal fields and frequencies.…”