The DUF Project: A UHV Factory for Multi-Interconnection of a Molecule Logic Gates on Insulating Substrate

Martrou, D.; Guiraud, Laurent; Laloo, Raphaël; Pécassou, Béatrice; Abeilhou, Pierre; Guillermet, Olivier; Dujardin, Erik; Gauthier, Sébastien; Polesel-Maris, Jérôme; Venegas, Miguel Ángel; Hinault, A.; Bodin, Andrey Yu.; Chaumeton, Florian; Piednoir, Agnès; Hua, Guo; Leoni, Thomas

doi:10.1007/978-3-642-28172-3_4

Cited by 2 publications

(3 citation statements)

References 37 publications

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“…When the AlN ð2 × 2Þ-N ad reconstructed surface is covered with at least 1 monolayer (ML) of gold, twofold streaks are no more visible in the RHEED pattern, meaning that the (2 × 2) periodicity disappears. NC AFM experiments are conducted with a room temperature (RT) UHV NC AFM (Scienta Omicron Nanotechnology GmbH, Taunusstein, Germany) belonging to the same UHV setup as the MBE chamber [15,16]. We used silicon cantilevers (NanoSensors PPP-QNCHR) with resonance frequencies between 280 and 300 kHz and quality factors between 32 000 and 40 000.…”

Section: Methodsmentioning

confidence: 99%

“…However, such single molecules have to be contacted to metallic nanoelectrodes, which should be two-dimensional (2D) islands with less than two monatomic layers in height to allow imaging the connected object with an atomic force microscope (AFM). These 2D islands are able to play the role of charge reservoirs or intermediate electrodes to be contacted by the tips of a multiprobe ultrahigh vacuum (UHV) instrument [15][16][17].…”

Section: Introductionmentioning

confidence: 99%

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Stabilization of Au Monatomic-High Islands on the (2×2)−Nad Reconstructed Surface of Wurtzite AlN(0001)

et al. 2017

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Noncontact atomic force microscopy images show that gold grows on the ð2 × 2Þ-N ad reconstructed polar (0001) surface of AlN insulating films, in the form of large monatomic islands. High-resolution images and in situ reflection high-energy electron diffraction spectra reveal two moiré patterns from which an atomic model can be built. Density functional theory calculations confirm this model and give insight into the mechanisms that lead to the stabilization of the monolayer. Gold adsorption is accompanied, first, by a global vertical charge transfer from the AlN substrate that fulfills the electrostatic stability criterion for a polar material, and second, by lateral charge transfers that are driven by the local chemical properties of the ð2 × 2Þ-N ad reconstruction. These results present alternative strategies to grow metal electrodes onto nitride compounds with a better controlled interface, a crucial issue for applications.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Stabilization of Au Monatomic-High Islands on the (2×2)−Nad Reconstructed Surface of Wurtzite AlN(0001)

et al. 2017

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“…In the case of nitride semiconductors, the layers should be grown under ultrahigh vacuum (UHV) and then transferred into an AFM chamber under UHV, since their surfaces are not stable in air. We were able to realize the NC-AFM study of AlN(0001) using custom-made equipment [30] where the AlN layer is grown by molecular beam epitaxy (MBE) using ammonia (NH 3 ) as nitrogen precursor and transferred under UHV to a room-temperature AFM. With the help of calculations based on density functional theory (DFT), coupled to the experimental reflection high-energy electron diffraction (RHEED) and NC-AFM measurements acquired for two different growth conditions, we proposed to assign one of the obtained surfaces to a (2 × 2) reconstruction involving one additional N atom per unit cell, and the other to a mixing between two alternative reconstructions functionalized by hydrogen.…”

mentioning

confidence: 99%

Noncontact atomic force microscopy and density functional theory studies of the (2×2) reconstructions of the polar AlN(0001) surface

et al. 2016

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Combined experimental and theoretical studies permit us to determine new protocols for growing by molecular beam epitaxy the technologically interesting N-rich aluminum nitride (AlN) surfaces. This is achieved by dosing the precursor gases at unusually low rates. With the help of calculated structures by using density functional theory and Boltzmann distribution of the reconstructed cells, we proposed to assign the measured surface obtained with a growth rate of 10 nm/h to a (2 × 2) reconstructed surface involving one additional N atom per unit cell. These N-rich AlN surfaces could open new routes to dope AlN layers with important implications in high-power and temperature technological applications. DOI: 10.1103/PhysRevB.94.165305 High-power electronic devices require materials with large electron mobilities and densities and large band gaps. Group-III nitride semiconductors are ideal candidates for these applications [1]. Among these materials, aluminum nitride (AlN) has the largest band gap [2]. It also has unique properties such as small density, large stiffness, large piezoelectric constant [3], large fracture resistivity, and chemical inertness [4]. Recently, the two-dimensional electron gases appearing at the interface of a strained GaN quantum well sandwiched between relaxed AlN layers have permitted the realization of field effect transistors with a high cut-off frequency of 104 GHz [5]. Unfortunately, defects and interface states seriously compromise devices based on these materials and there is an urgent need for high-quality interfaces and surfaces. For these reasons, its surface reconstructions have received a lot of attention theoretically [6][7][8][9][10][11]. Furthermore, due to its high ionicity, AlN crystallizes in the wurtzite structure and its (0001) growth surface is polar, like other zinc-blende (001) semiconductor surfaces [12]. The consequence of this polarity is that the crystal should be stabilized by the formation of surface charges that can be generated by different mechanisms like surface reconstructions (see the review article by Noguera [13], and references therein).Experimentally, due to the large gap of AlN (6.2 eV) it is not possible to observe its surface by scanning tunneling microscopy (STM) except for the Al rich phase as explored by Lee et al. [14]. One effective way to get information at the atomic scale is to use atomic-force microscopy in the noncontact mode (NC-AFM), as developed by Albrecht et al. in 1991 [15]. NC-AFM allows the observation of surfaces with atomic resolution of some ionic [16][17][18][19] . All these substrates can be prepared by cleavage or ionic bombardment followed by a soft annealing. In the case of nitride semiconductors, the layers should be grown under ultrahigh vacuum (UHV) and then transferred into an AFM chamber under UHV, since their surfaces are not stable in air. We were able to realize the NC-AFM study of AlN(0001) using custom-made equipment [30] where the AlN layer is grown by molecular beam epitaxy (MBE) using ammonia (NH 3 ) as n...

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The DUF Project: A UHV Factory for Multi-Interconnection of a Molecule Logic Gates on Insulating Substrate

Cited by 2 publications

References 37 publications

Stabilization of Au Monatomic-High Islands on the (2×2)−Nad Reconstructed Surface of Wurtzite AlN(0001)

Stabilization of Au Monatomic-High Islands on the (2×2)−Nad Reconstructed Surface of Wurtzite AlN(0001)

Noncontact atomic force microscopy and density functional theory studies of the (2×2) reconstructions of the polar AlN(0001) surface

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