In the molecular electronics field it is highly desirable to engineer the structure of molecules ... more In the molecular electronics field it is highly desirable to engineer the structure of molecules to achieve specific functions. In particular, diode (or rectification) behaviour in single molecules is an attractive device function. Here we study charge transport through symmetric tetraphenyl and non-symmetric diblock dipyrimidinyldiphenyl molecules covalently bound to two electrodes. The orientation of the diblock is controlled through a selective deprotection strategy, and a method in which the electrode-electrode distance is modulated unambiguously determines the current-voltage characteristics of the single-molecule device. The diblock molecule exhibits pronounced rectification behaviour compared with its homologous symmetric block, with current flowing from the dipyrimidinyl to the diphenyl moieties. This behaviour is interpreted in terms of localization of the wave function of the hole ground state at one end of the diblock under the applied field. At large forward current, the molecular diode becomes unstable and quantum point contacts between the electrodes form.
The charge transport characteristics of a family of long conjugated molecular wires have been stu... more The charge transport characteristics of a family of long conjugated molecular wires have been studied using the scanning tunneling microscope break junction technique. The family consists of four wires ranging from 3.1 to 9.4 nm in length. The two shortest wires show highly length dependent and temperature invariant conductance behavior, whereas the longer two wires show weakly length dependent and temperature variant behavior. This trend is consistent with a model whereby conduction occurs by two different mechanisms in the family of wires: by a coherent tunneling mechanism in the shorter two and by an incoherent charge hopping process in the longer wires. The temperature dependence of the two conduction mechanisms gives rise to a phenomenon whereby at elevated temperatures longer molecules that conduct via charge hopping can yield a higher conductance than shorter wires that conduct via tunneling. The evolution of molecular junctions as the tip retracts has been studied and explained in context of the characteristics of individual transient current decay curves.
Controlling the spin of electrons in nanoscale electronic devices is one of the most promising to... more Controlling the spin of electrons in nanoscale electronic devices is one of the most promising topics aimed at developing devices with rapid and highly dense information storage capabilities. The interface magnetism or spinterface resulting from the interaction between a magnetic molecule and a metal surface, or vice versa, has become a key ingredient in creating nanoscale molecular devices with novel functionalities. Here, we present a single-molecule wire that displays large (>10000%) magnetoresistance switching. The molecular wire is built by trapping individual spin crossover Fe complexes between one Au electrode and one ferromagnetic Ni electrode at room temperature in a organic liquid medium. Large changes in the single-molecule conductance (>100-fold) are measured when the electrons flow from the Au electrode to either an α-up or a β-down spin-polarized Ni electrode. Our calculations show that the current flowing through such an interface appears to be strongly spin-pol...
ISTFA 2021: Conference Proceedings from the 47th International Symposium for Testing and Failure Analysis
Semiconductor manufacturing has been outsourced to un-trusted regions due to globalization. The c... more Semiconductor manufacturing has been outsourced to un-trusted regions due to globalization. The complex multistep fabrication of micro-scale integrated circuits (ICs) and the tedious assembly of macro-scale Printed Circuit Boards (PCBs) are vulnerable to malicious attacks from design to final delivery. PCBs provide the functional connections of Integrated Circuits (ICs), sensors, power supplies, etc. of many critical electronic systems for consumers, corporations, and governments. The feature sizes of PCB signal traces in 2D and vias in 3D are an order of magnitude larger than IC devices, and are thereby more vulnerable to non-destructive attacks such as X-ray or probing. Active and passive countermeasures have been successfully developed for IC devices, however PCBs devices are difficult to wholly secure from all attacks. Passive countermeasures for X-ray attacks using high-z materials to block and scatter X-rays are effective, but there is a lack of active and passive countermeasu...
Page 1. Last advances in single-molecule electric contacts Ismael Díez-Pérez, Josh Hihath, Thomas... more Page 1. Last advances in single-molecule electric contacts Ismael Díez-Pérez, Josh Hihath, Thomas Hines, Zhihai Li, Nongjian Tao ... [2] BQ Xu and NJ. Tao Science 301 (2003) 1221. [3] X. Li, J. He, J. Hihath, B. Xu, SM Lindsay, NJ. Tao JACS 128 (2006) 2135. ...
Page 1. Last advances in single-molecule electric contacts Ismael Díez-Pérez, Josh Hihath, Thomas... more Page 1. Last advances in single-molecule electric contacts Ismael Díez-Pérez, Josh Hihath, Thomas Hines, Zhihai Li, Nongjian Tao ... [2] BQ Xu and NJ. Tao Science 301 (2003) 1221. [3] X. Li, J. He, J. Hihath, B. Xu, SM Lindsay, NJ. Tao JACS 128 (2006) 2135. ...
Controlling the spin of electrons in nanoscale electronic devices is one of the most promising to... more Controlling the spin of electrons in nanoscale electronic devices is one of the most promising topics aimed at developing devices with rapid and highly dense information storage capabilities. The interface magnetism or spinterface resulting from the interaction between a magnetic molecule and a metal surface, or vice versa, has become a key ingredient in creating nanoscale molecular devices with novel functionalities. Here, we present a single-molecule wire that displays large (>10000%) conductance switching by controlling the spin-dependent transport under ambient conditions (room temperature in a liquid cell). The molecular wire is built by trapping individual spin crossover FeII complexes between one Au electrode and one ferromagnetic Ni electrode in an organic liquid medium. Large changes in the single-molecule conductance (>100-fold) are measured when the electrons flow from the Au electrode to either an α-up or a β-down spin-polarized Ni electrode. Our calculations show ...
DNA is a promising molecule for applications in molecular electronics because of its unique elect... more DNA is a promising molecule for applications in molecular electronics because of its unique electronic and self-assembly properties. Here we report that the conductance of DNA duplexes increases by approximately one order of magnitude when its conformation is changed from the B-form to the A-form. This large conductance increase is fully reversible, and by controlling the chemical environment, the conductance can be repeatedly switched between the two values. The conductance of the two conformations displays weak length dependencies, as is expected for guanine-rich sequences, and can be fit with a coherence-corrected hopping model. These results are supported by ab initio electronic structure calculations that indicate that the highest occupied molecular orbital is more disperse in the A-form DNA case. These results demonstrate that DNA can behave as a promising molecular switch for molecular electronics applications and also provide additional insights into the huge dispersion of DNA conductance values found in the literature.
In the molecular electronics field it is highly desirable to engineer the structure of molecules ... more In the molecular electronics field it is highly desirable to engineer the structure of molecules to achieve specific functions. In particular, diode (or rectification) behaviour in single molecules is an attractive device function. Here we study charge transport through symmetric tetraphenyl and non-symmetric diblock dipyrimidinyldiphenyl molecules covalently bound to two electrodes. The orientation of the diblock is controlled through a selective deprotection strategy, and a method in which the electrode-electrode distance is modulated unambiguously determines the current-voltage characteristics of the single-molecule device. The diblock molecule exhibits pronounced rectification behaviour compared with its homologous symmetric block, with current flowing from the dipyrimidinyl to the diphenyl moieties. This behaviour is interpreted in terms of localization of the wave function of the hole ground state at one end of the diblock under the applied field. At large forward current, the molecular diode becomes unstable and quantum point contacts between the electrodes form.
The charge transport characteristics of a family of long conjugated molecular wires have been stu... more The charge transport characteristics of a family of long conjugated molecular wires have been studied using the scanning tunneling microscope break junction technique. The family consists of four wires ranging from 3.1 to 9.4 nm in length. The two shortest wires show highly length dependent and temperature invariant conductance behavior, whereas the longer two wires show weakly length dependent and temperature variant behavior. This trend is consistent with a model whereby conduction occurs by two different mechanisms in the family of wires: by a coherent tunneling mechanism in the shorter two and by an incoherent charge hopping process in the longer wires. The temperature dependence of the two conduction mechanisms gives rise to a phenomenon whereby at elevated temperatures longer molecules that conduct via charge hopping can yield a higher conductance than shorter wires that conduct via tunneling. The evolution of molecular junctions as the tip retracts has been studied and explained in context of the characteristics of individual transient current decay curves.
Controlling the spin of electrons in nanoscale electronic devices is one of the most promising to... more Controlling the spin of electrons in nanoscale electronic devices is one of the most promising topics aimed at developing devices with rapid and highly dense information storage capabilities. The interface magnetism or spinterface resulting from the interaction between a magnetic molecule and a metal surface, or vice versa, has become a key ingredient in creating nanoscale molecular devices with novel functionalities. Here, we present a single-molecule wire that displays large (>10000%) magnetoresistance switching. The molecular wire is built by trapping individual spin crossover Fe complexes between one Au electrode and one ferromagnetic Ni electrode at room temperature in a organic liquid medium. Large changes in the single-molecule conductance (>100-fold) are measured when the electrons flow from the Au electrode to either an α-up or a β-down spin-polarized Ni electrode. Our calculations show that the current flowing through such an interface appears to be strongly spin-pol...
ISTFA 2021: Conference Proceedings from the 47th International Symposium for Testing and Failure Analysis
Semiconductor manufacturing has been outsourced to un-trusted regions due to globalization. The c... more Semiconductor manufacturing has been outsourced to un-trusted regions due to globalization. The complex multistep fabrication of micro-scale integrated circuits (ICs) and the tedious assembly of macro-scale Printed Circuit Boards (PCBs) are vulnerable to malicious attacks from design to final delivery. PCBs provide the functional connections of Integrated Circuits (ICs), sensors, power supplies, etc. of many critical electronic systems for consumers, corporations, and governments. The feature sizes of PCB signal traces in 2D and vias in 3D are an order of magnitude larger than IC devices, and are thereby more vulnerable to non-destructive attacks such as X-ray or probing. Active and passive countermeasures have been successfully developed for IC devices, however PCBs devices are difficult to wholly secure from all attacks. Passive countermeasures for X-ray attacks using high-z materials to block and scatter X-rays are effective, but there is a lack of active and passive countermeasu...
Page 1. Last advances in single-molecule electric contacts Ismael Díez-Pérez, Josh Hihath, Thomas... more Page 1. Last advances in single-molecule electric contacts Ismael Díez-Pérez, Josh Hihath, Thomas Hines, Zhihai Li, Nongjian Tao ... [2] BQ Xu and NJ. Tao Science 301 (2003) 1221. [3] X. Li, J. He, J. Hihath, B. Xu, SM Lindsay, NJ. Tao JACS 128 (2006) 2135. ...
Page 1. Last advances in single-molecule electric contacts Ismael Díez-Pérez, Josh Hihath, Thomas... more Page 1. Last advances in single-molecule electric contacts Ismael Díez-Pérez, Josh Hihath, Thomas Hines, Zhihai Li, Nongjian Tao ... [2] BQ Xu and NJ. Tao Science 301 (2003) 1221. [3] X. Li, J. He, J. Hihath, B. Xu, SM Lindsay, NJ. Tao JACS 128 (2006) 2135. ...
Controlling the spin of electrons in nanoscale electronic devices is one of the most promising to... more Controlling the spin of electrons in nanoscale electronic devices is one of the most promising topics aimed at developing devices with rapid and highly dense information storage capabilities. The interface magnetism or spinterface resulting from the interaction between a magnetic molecule and a metal surface, or vice versa, has become a key ingredient in creating nanoscale molecular devices with novel functionalities. Here, we present a single-molecule wire that displays large (>10000%) conductance switching by controlling the spin-dependent transport under ambient conditions (room temperature in a liquid cell). The molecular wire is built by trapping individual spin crossover FeII complexes between one Au electrode and one ferromagnetic Ni electrode in an organic liquid medium. Large changes in the single-molecule conductance (>100-fold) are measured when the electrons flow from the Au electrode to either an α-up or a β-down spin-polarized Ni electrode. Our calculations show ...
DNA is a promising molecule for applications in molecular electronics because of its unique elect... more DNA is a promising molecule for applications in molecular electronics because of its unique electronic and self-assembly properties. Here we report that the conductance of DNA duplexes increases by approximately one order of magnitude when its conformation is changed from the B-form to the A-form. This large conductance increase is fully reversible, and by controlling the chemical environment, the conductance can be repeatedly switched between the two values. The conductance of the two conformations displays weak length dependencies, as is expected for guanine-rich sequences, and can be fit with a coherence-corrected hopping model. These results are supported by ab initio electronic structure calculations that indicate that the highest occupied molecular orbital is more disperse in the A-form DNA case. These results demonstrate that DNA can behave as a promising molecular switch for molecular electronics applications and also provide additional insights into the huge dispersion of DNA conductance values found in the literature.
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