A study of Si(111) 5 × 2-Au structures by Li adsorption and their coadsorbed superstructures

Daimon, Hiroshi; Chung, C.; Ino, Shuichi; Watanabe, Yousuke

doi:10.1016/0039-6028(90)90789-b

Cited by 52 publications

(3 citation statements)

References 15 publications

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“…This surface is prepared by depositing a half atomic-layer thick Au on the Si(1 1 1)-(7 Â 7) surface kept around 500 C. The superlattice spots cut the line between O and B into five parts as shown in Figure 6d, while a streak bisects the line between O and C. This means that the fivefold periodicity in b direction is perfect, while the double periodicity in ã direction is imperfect. This is a structure in direct space that one-dimensional chains having a double-fold periodicity (2a) along the chain are aligned every five-time spacing (5b), without correlation among them in the chain direction (Daimon et al, 1990). So the surface is called a 5 Â '2' structure with quotation marks on 2.…”

Section: Data Analysis and Initial Interpretationmentioning

confidence: 99%

Reflection High‐Energy Electron Diffraction

Hasegawa

2012

Characterization of Materials

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The fundamentals, experimental techniques, and practical aspects of reflection high‐energy electron diffraction (RHEED) are described with some examples of observations. Actual samples that we deal with in experiments are in many cases far from ideal ones; the surfaces are not perfectly single‐crystalline with infinitely large domains, or not atomically flat. The RHEED patterns are then modified from the theoretical ones for ideal samples. Inversely, from such modifications in the patterns, we can obtain various kinds of information on the atomic structures of surfaces and thin films. Examples of RHEED analyses presented here include monitoring structural phase transitions and epitaxial growth of atomic layers. RHEED has advantages in observing such dynamical phenomena of structure changes.

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Section: Data Analysis and Initial Interpretationmentioning

confidence: 99%

Reflection High‐Energy Electron Diffraction

Hasegawa

2012

Characterization of Materials

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“…The L-tyrosine molecule align in a periodicity of "2.3" along the row, but these is no correlation between rows. This structure, which correlated (periodicity 2.3) in one direction and uncorrelated (periodicity 5) in another direction, is similar to that of Si(111)"5×2"-Au structure [23,24]. Figure 7(b) is a close-up of the aligned adsorbates at the dosage of 0.034 ML.…”

Section: Resultsmentioning

confidence: 56%

Regular Array of L-Tyrosine Molecules on Si(111)-Au Superstructures

Yoshimura

Matsui

Daimon

2010

e-J. Surf. Sci. Nanotechnol.

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Studies of adsorption of organic molecules on metal-induced super-reconstructed silicon surfaces are important for future Si-based organic electronic device. We investigated the adsorption dynamics of L-tyrosine on Si-Au surface by in situ reflection high-energy electron diffraction. Si(111)5×2-Au and Si(111) √ 3× √ 3-Au coexisting surface was exposed to L-tyrosine and the intensities of diffraction spots from corresponding domains were monitored. Ltyrosine was found to adsorb onto the Si(111)5×2-Au domains preferentially, while the Si(111) √ 3× √ 3-Au domains were found to be less active. Adsorption sites were revealed by using scanning tunneling microscopy. The molecular adsorption site on the √ 3× √ 3-Au was found to be on domain boundary suggesting that the adsorption probability is small on this domain. On the other hand, the adsorbates ordering in 2.3 unit cell distance along [110] rows were found to create the similar structure as the Si(111)5×2-Au surface. These results suggest that the Si(111)5×2-Au superstructure can be used for the control of the molecular adsorption geometry and ordering effectively.

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“…The deposition rate was calibrated in situ by analyzing the diffraction patterns and REM images during gold deposition on the Si(111) surface at 500 0 C. At this temperature, gold adsorption initiates the formation of an Si(111)-5x2-Au superstructure leading to the appearance of additional reflections in the RHEED patterns. The amount of gold corresponding to the surface fully covered by 5 x 2-Au domains was used as a reference point and assumed to be 0.43 ± 0.14 monolayers (ML), where 1 ML of gold corresponds to 7.8 x 10 14 cm -2 [14,15]. The total amount of gold deposited during the high-temperature experiments was measured in monolayers as a product of the deposition rate and time.…”

Section: Methodsmentioning

confidence: 99%

Real-time observation of self-interstitial reactions on an atomically smooth silicon surface

et al. 2019

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Self-diffusion and impurity diffusion both play crucial roles in the fabrication of semiconductor nanostructures with high surface-to-volume ratios. However, experimental studies of bulk-surface reactions of point defects in semiconductors are strongly hampered by extremely low concentrations and difficulties in the visualization of single point defects in the crystal lattice.Herein we report the first real-time experimental observation of the self-interstitial reactions on a large atomically smooth silicon surface. We show that non-equilibrium self-interstitials generated in silicon bulk during gold diffusion in the temperature range 860-1000 o C are annihilated at the (111) surface, producing the net mass flux of silicon from the bulk to the surface. The kinetics of the two-dimensional islands formed by self-interstitials are dominated by the reactions at the atomic step edges. The activation energy for the interaction of self-interstitials with the surface and energy barrier for gold penetration into the silicon bulk through the surface are estimated.These results demonstrating that surface morphology can be profoundly affected by surface-bulk reactions should have important implications for the development of nanoscale fabrication techniques. 2 reactions of point defects at the surfaces and interfaces become predominant and may significantly modify the properties of fabricated nanostructures [8-11]. While the properties of point defects in bulk semiconductors have been extensively studied and are well understood, little is actually known about the point defect formation, reactions, and basic mechanisms of the diffusion in the vicinity of free surfaces. At the heart of the problem lies the need for direct visualization of the single point defect diffusion in crystal bulk, which is still lacking, especially at high temperatures, where diffusion is fast compared to the imaging rate of modern atomic-scale characterization techniques such as aberration-corrected high-resolution transmission electron microscopy (HRTEM). In addition, the extremely low concentrations of point defects in silicon make their observation quite difficult. On the other hand, the direct visualization of single atoms, vacancies, and their clusters on crystal surfaces has become routine with the development of surface-sensitive techniques such as scanning tunneling (STM), atomic force (AFM), low-energy (LEEM), and reflection electron microscopy (REM). However, atomic steps that are an inherent part of all crystalline surfaces, acting as sinks for adsorbed atoms and vacancies, hamper direct experimental studies of point defect properties.This study used high-temperature (860-1000 o C) submonolayer gold deposition onto an atomically smooth large size (up to 100 μm in diameter) step-free Si(111) surface to study the interaction of the native point defects (self-interstitials and vacancies) with the surface boundary, considering the finite efficiency for the penetration, annihilation, and creation of point defects at the surface.Since it is well ...

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A study of Si(111) 5 × 2-Au structures by Li adsorption and their coadsorbed superstructures

Cited by 52 publications

References 15 publications

Reflection High‐Energy Electron Diffraction

Reflection High‐Energy Electron Diffraction

Regular Array of L-Tyrosine Molecules on Si(111)-Au Superstructures

Real-time observation of self-interstitial reactions on an atomically smooth silicon surface

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