Anisotropic Standing-Wave Formation on an Au(111)-<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mo>(</mml:mo><mml:mn>23</mml:mn><mml:mo>×</mml:mo><mml:mi mathvariant="italic">√</mml:mi><mml:mn>3</mml:mn><mml:mo>)</mml:mo></mml:math>Reconstructed Surface

Fujita, Daisuke; Amemiya, Katsuki; Yakabe, Taro; Nejoh, H.; Sato, Tomoshige; Iwatsuki, Masashi

doi:10.1103/physrevlett.78.3904

Cited by 43 publications

(32 citation statements)

References 21 publications

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“…Such standing waves were first observed on metal surfaces independently by Eigler's group [8] and Avouris's group [9], and extended by several others [33][34][35][36]. They are essentialy the consequence of electron travelling waves bouncing off steps and other defect structures, leading to a selfinterference pattern that changes the probability for electrons tunnelling from the tip into the sample surface.…”

Section: Silicon(1 1 1): a Case Studymentioning

confidence: 99%

Electronic transport at semiconductor surfaces––from point-contact transistor to micro-four-point probes

Hasegawa

Grey

2002

Surface Science

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The electrical properties of semiconductor surfaces have played a decisive role in one of the most important discoveries of the last century, transistors. In the 1940s, the concept of surface states--new electron energy levels characteristic of the surface atoms--was instrumental in the fabrication of the first point-contact transistors, and led to the successful fabrication of field-effect transistors. However, to this day, one property of semiconductor surface states remains poorly understood, both theoretically and experimentally. That is the conduction of electrons or holes directly through the surface states. Since these states are restricted to a region only a few atom layers thick at a crystal surface, any signal from them might be swamped by conduction through the underlying bulk semiconductor crystal, as well as greatly perturbed by steps and other defects at the surface. Yet recent results show that this type of conduction is measurable using new types of experimental probes, such as the multi-tip scanning tunnelling microscope and the micro-four-point probe. The resulting electronic transport properties are intriguing, and suggest that semiconductor surfaces should be considered in their own right as a new class of electronic nanomaterials because the surface states have their own characters different from the underlying bulk states. As microelectronic devices shrink even further, and surface-to-volume ratios increase, surfaces will play an increasingly important role. These new nanomaterials could be crucial in the design of electronic devices in the coming decades, and also could become a platform for studying the physics of a new family of low-dimensional electron systems on nanometre scales. Ó

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Section: Silicon(1 1 1): a Case Studymentioning

confidence: 99%

Electronic transport at semiconductor surfaces––from point-contact transistor to micro-four-point probes

Hasegawa

Grey

2002

Surface Science

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“…Finally, we note that the negative charge and radial motion of isolated EU oxygen atoms modulate the neighboring electrondensity ripples, changing their height and period (20,24) (Fig. 4).…”

Section: (C) Relative Charge Density (Rcd) Of the Architecture As Viementioning

confidence: 99%

A 16-bit parallel processing in a molecular assembly

Bandyopadhyay

Acharya

2008

Proc. Natl. Acad. Sci. U.S.A.

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A machine assembly consisting of 17 identical molecules of 2,3,5,6-tetramethyl-1-4-benzoquinone (DRQ) executes 16 instructions at a time. A single DRQ is positioned at the center of a circular ring formed by 16 other DRQs, controlling their operation in parallel through hydrogen-bond channels. Each molecule is a logic machine and generates four instructions by rotating its alkyl groups. A single instruction executed by a scanning tunneling microscope tip on the central molecule can change decisions of 16 machines simultaneously, in four billion (4 16 ) ways. This parallel communication represents a significant conceptual advance relative to today's fastest processors, which execute only one instruction at a time.A molecular machine is a system that generates physical motion of its components at the atomic level, controlled by an external stimulus (1-10). Several novel nanomachines have been realized over the last two decades by rearranging the constituent atoms of nature's building blocks, namely proteins (11, 12), DNA (13), and other compounds (14-17). Researchers have sought to increase the number of versatile instructions and generate multiple operations by increasing the complexity of design via diverse assembly routes. However, a machine that can modulate the decisions of other machines or communicate with more than one system at a time has not yet been achieved. A major difficulty in realizing such a machine resides in transferring versatile instructions simultaneously at the molecular level in a well controlled manner, partly because such machines are beyond the reach of today's atomic-scale manipulation. Linear connection of machines allows implementation of only one instruction at a time. In contrast, the radial connection of machines originating from a central control would allow parallel communication similar to a synaptic channel, but this configuration has not been explored in reported machines. Construction of a machine to process parallel communication will require an encoded molecular assembler (MA) that will precisely position the operational molecules by weakly interacting bonds and translate multiple instructions.Recently, we have realized a multilevel switch in 2,3,5,6-tetramethyl-1-4-benzoquinone (duroquinone, DRQ) (Fig. 1A), which generates four logic states (0, 1, 2, and 3) within 7 Å when instructed by a suitable scanning tunneling microscope (STM) pulse. ‡ Each logic state is associated with particular rotation of alkyl groups, satisfying the requirement of a molecular machine. Here, we report a machine assembly consisting of 17 identical DRQs, wherein a single molecule simultaneously instructs 16 others, in 4 16 possible ways. This machine is made possible by a supramolecular architecture consisting of a ring of 16 analogous DRQs as execution units (EUs) around a single DRQ as central control unit (CCU). Hydrogen-bond channels originating from the CCU radially connect to the 16 EUs, providing synchronized one-to-many control of their states. Instructions are sent by STM pulse to the CCU...

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“…The coherence length of standing wave patterns is inversely proportional to the temperature of the surface, especially at T > 100 K where Fermi-Dirac broadening is the predominant factor in the damping process [41,42]. This coherence length ( C ) as a function of temperature (T) for surface-state electrons on a bare noble metal surface can be calculated from the following equation [41]:…”

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confidence: 99%

Long-Range Electronic Interactions at a High Temperature: Bromine Adatom Islands on Cu(111)

et al. 2007

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Long-range electronic interactions between Br adatom islands, which are formed at approximately 600 K, on Cu(111) are mediated by substrate surface-state electrons at that elevated temperature. Using scanning tunneling microscopy at 4 K, we have quantified nearest neighbor island separations and found favored spacings to be half-multiples of the Fermi wavelength of Cu(111). The strong interaction potential and decay length of the interisland interactions are discussed in terms of the interaction of Br with the substrate surface state.

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Anisotropic Standing-Wave Formation on an Au(111)-(23×√3)Reconstructed Surface

Cited by 43 publications

References 21 publications

Electronic transport at semiconductor surfaces––from point-contact transistor to micro-four-point probes

Electronic transport at semiconductor surfaces––from point-contact transistor to micro-four-point probes

A 16-bit parallel processing in a molecular assembly

Long-Range Electronic Interactions at a High Temperature: Bromine Adatom Islands on Cu(111)

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