Multilevel Atomic‐Scale Transistors Based on Metallic Quantum Point Contacts

Xie, Fangqing; Maul, R.; Obermair, Christian; Wenzel, Wolfgang; Schön, Gerd; Schimmel, Thomas

doi:10.1002/adma.200902953

Cited by 31 publications

(22 citation statements)

References 23 publications

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“…Although the development of the single-atom transistor just marks the beginning of actively controlled electronics on the atomic scale, it opens fascinating perspectives for quantum electronics and logics based on individual atoms. e development of a first, simple integrated circuit [1,14] and a multilevel quantum transistor [13] are first encouraging steps in this direction. …”

Section: Discussionmentioning

confidence: 99%

“…By developing a modified procedure of fabrication, a multi-level atomic quantum transistor was obtained, allowing the gate-controlled switching between different conducting states. Instead of setting the lower threshold where the dissolution process is stopped by the computer, to a value near 0 G o , the lower threshold was set at a value above the desired quantized conductance of the lower of the two "on-state" levels [13]. …”

Section: Mulitlevel Switchingmentioning

confidence: 99%

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The Single-Atom Transistor: perspectives for quantum electronics on the atomic-scale

2010

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ascinating physical properties and technological perspectives have motivated investigation of atomic-scale metallic point contacts in recent years [1][2][3][4][5][6][7][8][9][10]. e quantum nature of the electron is directly observable in a size range where the width of the contacts is comparable to the Fermi wavelength of the electrons, and conductance is quantized in multiples of 2e 2 /h for ballistic transport through ideal junctions [2]. In metallic point contacts, which have been fabricated by mechanically controlled deformation of thin metallic wires [2][3][4] and electrochemical fabrication techniques [1,[5][6][7], the conductance depends on the chemical valence [2,3]. Two-terminal conductance-switching devices based on quantum point contacts were developed both with an STM-like setup [8] and with electrochemical methods [9].In our new approach, a three-terminal, gate-controlled atomic quantum switch was fabricated by electrochemical deposition of silver between two nanoscale gold electrodes (see Fig. 1) [1,6]. A comparison of the experimental data with theoretical calculations indicates perfect atomic order within the contact area without volume or surface defects [10]. Switching an atomWe control individual atoms in the quantum point contact by a voltage applied to an independent gate electrode, which allows a reproducible switching of the contact between a quantized conducting "on-state" and an insulating "off-state" without any mechanical movement of an electrode (see Fig. 2). EPN 41/4 25Controlling the electronic conductivity on the quantum level will impact the development of future nanoscale electronic circuits with ultralow power consumption. Here we report about the invention of the single-atom transistor, a device which allows one to open and close an electronic circuit by the controlled and reproducible repositioning of one single atom. It opens intriguing perspectives for the emerging fields of quantum electronics and logics on the atomic scale.

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Section: Discussionmentioning

confidence: 99%

Section: Mulitlevel Switchingmentioning

confidence: 99%

The Single-Atom Transistor: perspectives for quantum electronics on the atomic-scale

2010

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“…Significant progress was also achieved in the field of the controlled electrochemical deposition of metals for the fabrication of atomic-scale contacts and switches. By electrochemical deposition of nanoscale silver contacts and subsequent electrochemical cycling, an electrically controllable single-atom relay was demonstrated, which allows the controlled switching of an electrical current by the control-voltage-induced movement of just a single atom [4–7]. In this way, a single-atom transistor was demonstrated as a quantum electronic device operating reproducibly at room temperature.…”

Section: Introductionmentioning

confidence: 99%

The atomic force microscope as a mechano–electrochemical pen

Obermair

Wagner²,

Schimmel³

2011

Beilstein J. Nanotechnol.

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SummaryWe demonstrate a method that allows the controlled writing of metallic patterns on the nanometer scale using the tip of an atomic force microscope (AFM) as a “mechano–electrochemical pen”. In contrast to previous experiments, no voltage is applied between the AFM tip and the sample surface. Instead, a passivated sample surface is activated locally due to lateral forces between the AFM tip and the sample surface. In this way, the area of tip–sample interaction is narrowly limited by the mechanical contact between tip and sample, and well-defined metallic patterns can be written reproducibly. Nanoscale structures and lines of copper were deposited, and the line widths ranged between 5 nm and 80 nm, depending on the deposition parameters. A procedure for the sequential writing of metallic nanostructures is introduced, based on the understanding of the passivation process. The mechanism of this mechano–electrochemical writing technique is investigated, and the processes of site-selective surface depassivation, deposition, dissolution and repassivation of electrochemically deposited nanoscale metallic islands are studied in detail.

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“…In this way, switching between a quantized conducting “on-state” and an insulating “off-state” is performed. Even multilevel quantum switches on the atomic scale were demonstrated very recently [6]. The possibility of training special atomic configurations related to certain conductance values, and the high stability of the chosen conductance levels, are unique features of the electrochemical method [4–10].…”

Section: Introductionmentioning

confidence: 99%

Lifetime analysis of individual-atom contacts and crossover to geometric-shell structures in unstrained silver nanowires

Obermair¹,

Kühn²,

Schimmel³

2011

Beilstein J. Nanotechnol.

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SummaryWe study the crossover of quantum point contacts from (i) individual-atom contacts to (ii) electronic-shell effects and finally to (iii) geometric-shell effects in electrochemically deposited silver contacts. The method allows the fabrication of mechanically unstrained structures, which is a requirement for determining the individual atomic configuration by means of a detailed lifetime analysis of their conductance. Within the geometric-shell model, the sequence of conductance maxima is explained quantitatively based on the crystal structure data of silver, and the growth mechanism of the nanowires is discussed.

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Multilevel Atomic‐Scale Transistors Based on Metallic Quantum Point Contacts

Cited by 31 publications

References 23 publications

The Single-Atom Transistor: perspectives for quantum electronics on the atomic-scale

The Single-Atom Transistor: perspectives for quantum electronics on the atomic-scale

The atomic force microscope as a mechano–electrochemical pen

Lifetime analysis of individual-atom contacts and crossover to geometric-shell structures in unstrained silver nanowires

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