Combining scanning tunneling microscope (STM) imaging and local manipulation to probe the high dose oxidation structure of the Si(111)-7×7 surface

Kaya, Doğan; Cobley, Richard J.; Palmer, Richard E.

doi:10.1007/s12274-019-2587-1

Cited by 5 publications

(15 citation statements)

References 51 publications

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“…1, the Si atom on top was still undercoordinated yielding a surface dangling bond. This exact configuration was already observed experimentally by STM images of a sparsely oxidized Si surface [26].…”

Section: O2 Adsorption Onto the Clean Si Surfacesupporting

confidence: 77%

“…This was confirmed experimentally in recent electron microscopy and photoemission studies [24][25][26]. In addition to directly dissociative O 2 adsorption, metastable molecular surface states were observed by means of scanning electron microscopy (SEM) and electron spectroscopy techniques on thin oxide layers [26][27][28][29][30]. These molecular states precede dissociation at low temperatures and vanish upon annealing.…”

Section: Introductionsupporting

confidence: 61%

“…Previous ab initio calculations showed that the initial oxidation of a clean Si surface is based on chemisorption events resulting in the dissociation of the adsorbing O 2 molecule directly at the surface [21][22][23]. This was confirmed experimentally in recent electron microscopy and photoemission studies [24][25][26]. In addition to directly dissociative O 2 adsorption, metastable molecular surface states were observed by means of scanning electron microscopy (SEM) and electron spectroscopy techniques on thin oxide layers [26][27][28][29][30].…”

Section: Introductionmentioning

confidence: 70%

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Modeling the Initial Stages of Si(100) Thermal Oxidation: An Ab-initio Approach

Cvitkovich¹,

Waldhoer²,

El-Sayed³

et al. 2022

Preprint

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Silicon together with its native oxide SiO2 was recognized as an outstanding material system for the semiconductor industry in the 1950s. In state-of-the-art device technology, SiO2 is widely used as an insulator in combination with high-k dielectrics such as HfO2, demanding fabrication of ultra-thin interfacial layers. The classical standard model derived by Deal and Grove accurately describes the oxidation of Si in a progressed stage, however, strongly underestimates growth rates for thin oxide layers. Recent studies report a variety of oxidation mechanisms during the growth of oxide films in the range of 10 A with various details still under debate. This paper presents a firstprinciples based approach to theoretically assess the thermal oxidation process of the technologically relevant Si(100) surface during this initial stage. Our investigations range from the chemisorption of single O2 molecules onto the p(2 × 2) reconstructed Si surface to oxidized Si surface layers with a thickness of up to 20 A. The initially observed enhanced growth rate is assigned to barrierless O2 chemisorption events upon which the oxygen molecule dissociate. We present strong evidence for an immediate amorphization of the oxide layer from the onset of oxidation. Following the oxidation of the first Si layers a slower oxygen incorporation mechanism is available by molecular precursor states that spontaneously dissociate after a few ps. This process dominates until the surface is saturated with oxygen and separated from the Si substrate by a 5 A transition region. Despite the extremely thin layer, the oxide shows structural characteristics of bulk a-SiO2. The saturated surface becomes inert to dissociative reactions and enables the diffusion of molecular oxygen to the Si/SiO 2 interface as assumed within the Deal-Grove model. Further oxidation of the Si substrate is then provided by O2 dissociations at the interface due to the same charge transfer process responsible for the chemisorption at the surface.

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Section: O2 Adsorption Onto the Clean Si Surfacesupporting

confidence: 77%

Section: Introductionsupporting

confidence: 61%

Section: Introductionmentioning

confidence: 70%

See 1 more Smart Citation

Modeling the Initial Stages of Si(100) Thermal Oxidation: An Ab-initio Approach

Cvitkovich¹,

Waldhoer²,

El-Sayed³

et al. 2022

Preprint

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show abstract

“…To test the chemical sensitivity of APC-TERS, we also investigated the partially oxidized Si(111)-7 × 7 surface. The dark areas in the inset STM image (top-left) of Figure b correspond to the surface oxide . When APC-TERS is recorded at this dark area, three peaks are observed at higher frequency (>650 cm –1 ) where no Raman signals occur from the bare Si(111)-7 × 7 surface.…”

mentioning

confidence: 98%

Atomic Point Contact Raman Spectroscopy of a Si(111)-7 × 7 Surface

et al. 2021

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Tip-enhanced Raman scattering (TERS) has recently demonstrated the exceptional sensitivity to observe vibrational structures on the atomic scale. However, it strongly relies on electromagnetic enhancement in plasmonic nanogaps. Here, we demonstrate that atomic point contact (APC) formation between a plasmonic tip and the surface of a bulk Si sample can lead to a dramatic enhancement of Raman scattering and consequently the phonons of the reconstructed Si(111)-7 × 7 surface can be detected. Furthermore, we demonstrate the chemical sensitivity of APC-TERS by probing local vibrations resulting from Si−O bonds on the partially oxidized Si(111)-7 × 7 surface. This approach will expand the applicability of ultrasensitive TERS, exceeding the previous measurement strategies that exploit intense gap-mode plasmons, typically requiring a plasmonic substrate.

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“…With the progression of atomic-level testing technology [1,2], a series of interesting dynamic phenomena [3,4] on the solid surface, such as the formation of typical structures and fluctuation of the step region [5,6], have been found. The important substrate material, Si (111)-(7 × 7), is a reconstructed surface formed with many regular triangle structures in a horizontal directin.…”

Section: Introductionmentioning

confidence: 99%

Metal Deposition Induced by the Step Region of Si (111)-(7 × 7) Surface

Ding

Gong

et al. 2021

Coatings

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Scanning tunneling microscope results showed that Au and Fe atoms were steamed on the Si (111)-(7 × 7) substrate surface, with or without the step region. The experimental comparison proved that the induced effect of the step region is a controllable process, which CH3OH can adjust. In this paper, the latest progress on the dynamic phenomenon on the step region is discussed, including three deposition types: strong deposition, weak deposition, and the new quasi deposition. With a relatively weak interaction between Au and Si atoms, the linearity of the weak deposition is present in the step region. In contrast, Fe atoms tend to form a strong deposition along the boundary line between the flat and step regions. Different depositions correspond to different surface potential energy: a newly formed surface is stabilized by a quasi-potential made by breaking, and a metal atomic structure can be stabilized by forming several quasi depositions. After discussing the good adsorption properties, CH3OH can be used as an intermediate layer on the step region. As an important result of quasi deposition, a regular linear Fe cluster structure is created, which is perpendicular to the boundary line.

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Combining scanning tunneling microscope (STM) imaging and local manipulation to probe the high dose oxidation structure of the Si(111)-7×7 surface

Cited by 5 publications

References 51 publications

Modeling the Initial Stages of Si(100) Thermal Oxidation: An Ab-initio Approach

Modeling the Initial Stages of Si(100) Thermal Oxidation: An Ab-initio Approach

Atomic Point Contact Raman Spectroscopy of a Si(111)-7 × 7 Surface

Metal Deposition Induced by the Step Region of Si (111)-(7 × 7) Surface

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