Growth mode and novel structure of ultra-thin KCl layers on the Si(100)-2×1 surface

Tsay, Shiow-Fon; Chung, Jen-Yang; Hsieh, Ming‐Feng; Ferng, Shyh-Shin; Lou, Changshuan; Lin, Deng-Sung

doi:10.1016/j.susc.2008.12.010

Cited by 7 publications

(9 citation statements)

References 19 publications

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“…[8][9][10] However, Tsay et al found that KCl can grow on Si(100) in a layer-by-layer fashion. 11 In the present work, NaCl nanofilms were grown by means of MBE and the resulting films were examined in situ by high-resolution synchrotron radiation photoemission and STM. Ab initio calculations were also applied to model the atomic structure of the first adlayer.…”

Section: Introductionmentioning

confidence: 99%

Sodium chloride on Si(100) grown by molecular beam epitaxy

Chung

Chang

et al. 2011

Phys. Rev. B

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Sodium chloride (NaCl) films were grown on an Si(100)-(2 × 1) surface at near room temperature by molecular beam epitaxy (MBE). The atomic structure and growth mode of the prototypical ionic materials on the covalent bonded semiconductor surface is examined by synchrotron core-level x-ray photoemission spectrum (XPS), scanning tunneling microscopy (STM), and first-principles calculations. The Si 2p, Na 2p, and Cl 2p core-level spectra together indicate that adsorbed NaCl molecules at submonolayer coverage [i.e., below 0.4 monolayer (ML)] partially dissociate and form Si-Cl species, and that a significant portion of the dangling-bond characteristics of the clean surface remains after NaCl deposition of 1.8 MLs. The deposition of 0.65-ML NaCl forms a partially ordered adlayer, which includes NaCl networks, Si-Cl species, adsorbed Na species, and isolated dangling bonds. The STM results revealed that the first adlayer consists of bright protrusions which form small c(2 × 4) and (2 × 2) patches. Above 0.65 ML, the two-dimensional NaCl double-layer growth proceeds on top of the first adlayer.

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Section: Introductionmentioning

confidence: 99%

Sodium chloride on Si(100) grown by molecular beam epitaxy

Chung

Chang

et al. 2011

Phys. Rev. B

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“…An appealing approach is to grow ultra thin layers of insulators (like NaCl, KCl, etc) on singlecrystal metal surfaces. By just varying the thickness of the ultra thin layer, which is a standard procedure in surface physics, one would like to exert some control on the metal response, similar to that required to gradually modify the catalytic activity of metallic species [51][52][53][54][55][56] , to decouple molecules and self-assembled molecular networks from the metal substrate that holds them [57][58][59][60], and, what is more important in the context of the present work, to gradually modify the response of metal surface electrons [61][62][63][64][65][66][67]. Inspired by the latter works, we propose a similar strategy to tune the harmonic cut-off.…”

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confidence: 99%

Tuning high-harmonic generation by controlled deposition of ultrathin ionic layers on metal surfaces

Aguirre

Martín

2016

Phys. Rev. B

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High harmonic generation (HHG) from semiconductors and insulators has become a very active area of research due to its great potential for developing compact HHG devices. Here we show that by growing monolayers (ML) of insulators on single-crystal metal surfaces, one can tune the harmonic spectrum by just varying the thickness of the ultrathin layer, not the laser properties. This is shown from numerical solutions of the time-dependent Schrödinger equation for nML NaCl/Cu(111) systems (n = 1 − 50) based on realistic potentials available in the literature. Remarkably, the harmonic cutoff increases linearly with n and as much as an order of magnitude when going from n = 1 to 30, while keeping the laser intensity low and the wavelength in the near-infrared range. Furthermore, the degree of control that can be achieved in this way is much higher than by varying the laser intensity. The origin of this behavior is the reduction of electronic "friction" when moving from the essentially discrete energy spectrum associated with a few-ML system to the continuous energy spectrum (bands) inherent to an extended periodic system. PACS numbers: 42.65. Ky,78.66.Nk, Discovered in the 1980's [1-3], high harmonic generation (HHG) has become the fundamental tool of modern attoscience [4][5][6]. In HHG from atomic or molecular gases, a strong laser field ionizes an electron, which then gains energy from the field and returns to the parent ion, where it finally recombines converting the gained energy into high-frequency radiation [7][8][9][10]. The process repeats every half-cycle of the ionizing field, thus leading to a sequence of attosecond light bursts that contain multiples of the fundamental laser frequency, ω 0 . Since electronic motion in atomic and molecular systems occurs in the attosecond time scale, light pulses arising from HHG are currently used to probe electron dynamics in those systems [11][12][13][14][15][16][17][18]. Furthermore the HHG process itself contains the signature of the parent-ion dynamics occurring during the round trip of the traveling electron. Thus the analysis of the HHG spectral features can also reveal important aspects of such dynamics [19][20][21][22][23][24][25].HHG from condensed matter systems was first observed in the mid 90s [26,27]. In these early experiments, bulk metals and dielectrics irradiated with very intense near-infrared laser fields (of the order of 10 18 W/cm 2 ) were shown to emit harmonic radiation as a result of plasma oscillations induced in the system (see also [28]) Due to the high intensity of the field, HHG was always accompanied by sample damage. More recent experiments have made use of nano tips and nano spheres [29][30][31][32][33], from which HHG has been produced by using relatively moderate fields (of the order of 10 12 W/cm 2 ). HHG has also been observed in bulk semiconductors and insulators [34][35][36][37][38][39][40] by using similar low intensities (even lower than those usually needed to generate high harmonics in the gas phase) and longer wavelengths, down ...

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“…The polar surfaces, however, possess uncompensated net dipole moments perpendicular to the surface, which leads to an increase of the surface free energy making them unstable 13 19 . The vast majority of studies of alkali-halide thin films grown on metals 20 21 22 23 24 25 26 27 and semiconductors 8 9 10 confirms this fact. However, if some specific requirements are fulfilled, NaCl(111) islands with the uppermost layer corresponding to a polar surface can also be grown, like on Al(111) and Al(001) 2 .…”

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confidence: 79%

“…The growth of thin alkali halide films on metal 1 2 3 4 5 6 7 and, in a lesser extent, on semiconductor substrates 8 9 10 has been the subject of many studies for the last two decades. Apart from a fundamental interest in such films, an emerging topic concerns the formation of supramolecular 11 12 14 and covalent 15 assemblies on such substrates for rising applications in organic electronics or molecule-based sensing devices since it has been recently shown that ultrathin NaCl layers grown on metal surfaces can be beneficially used for the efficient electronic decoupling of adsorbates from the conductive substrates 16 17 18 .…”

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confidence: 99%

KCl ultra-thin films with polar and non-polar surfaces grown on Si(111)7 × 7

Beinik

Barth

Hanbücken

et al. 2015

Sci Rep

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The growth of ultra-thin KCl films on the Si(111)7 × 7 reconstructed surface has been investigated as a function of KCl coverage and substrate temperature. The structure and morphology of the films were characterized by means of scanning tunneling microscopy (STM) under ultra-high vacuum (UHV) conditions. Detailed analysis of the atomically resolved STM images of islands grown at room and high temperatures (400 K–430 K) revealed the presence of KCl(001) and KCl(111) islands with the ratio between both structures depending on the growth temperature. At room temperature, the growth of the first layer, which covers the initial Si(111)7 × 7 surface, contains double/triple atomic layers of KCl(001) with a small fraction of KCl(111) islands. The high temperature growth promotes the appearance of large KCl(111) areas, which are built up by three atomic layers. At room and high temperatures, flat and atomically well-defined ultra-thin KCl films can be grown on the Si(111)7 × 7 substrate. The formation of the above mentioned (111) polar films is interpreted as a result of the thermally activated dissociative adsorption of KCl molecules on Si(111)7 × 7, which produces an excess of potassium on the Si surface.

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Growth mode and novel structure of ultra-thin KCl layers on the Si(100)-2×1 surface

Cited by 7 publications

References 19 publications

Sodium chloride on Si(100) grown by molecular beam epitaxy

Sodium chloride on Si(100) grown by molecular beam epitaxy

Tuning high-harmonic generation by controlled deposition of ultrathin ionic layers on metal surfaces

KCl ultra-thin films with polar and non-polar surfaces grown on Si(111)7 × 7

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