Stability of hydrogen-terminated vicinal Si(111) surface under ambient atmosphere

Kolı́bal, Miroslav; Čechal, Jan; Bartošík, Miroslav; Mach, Jindřich; Šikola, Tomáš

doi:10.1016/j.apsusc.2009.12.045

Cited by 16 publications

(16 citation statements)

References 27 publications

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“…A pressure exponent of β = 0.7 is explained by the similarity in barriers for two types of dissociation events: O 2 inserted into Si-Si backbonds that share the same Si-H bond; and, insertions into two separated Si-H bonds. These observations are consistent with a recent work 30 wherein similarly prepared H-Si(111) was exposed to an ambient atmosphere. Although the measurements were performed at a single temperature, T = 293.15 K, the prefactor of 10 13 -10 15 determined by Zhang et al 29 As an alternative to H passivation, alkyl groups are also widely used to terminate Si surfaces due to their flexibility, biocompatibility, and stability in a wide range of environments.…”

Section: Introductionsupporting

confidence: 93%

First principles analysis of the initial oxidation of Si(001) and Si(111) surfaces terminated with H and CH3

Lin

et al. 2012

The Journal of Chemical Physics

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Transition state analyses have been carried out within a density functional theory setting to explain and quantify the distinctly different ways in which hydrogen and methyl terminations serve to protect silicon surfaces from the earliest onset of oxidation. We find that oxidation occurs via direct dissociative adsorption, without any energy barrier, on Si(111) and reconstructed Si(001) that have been hydrogen terminated; oxidation initiates with a barrier of only 0.05 eV on unreconstructed Si(001). The commonly measured protection afforded by hydrogen is shown to derive from a coverage-dependent dissociation rate combined with barriers to the hopping of adsorbed oxygen atoms. Methyl termination, in contrast, offers an additional level of protection because oxygen must first undergo interactions with these ligands in a three-step process with significant energy barriers: adsorption of O(2) into a C-H bond to form a C-O-O-H intermediate; decomposition of C-O-O-H into C-O-H and C=O intermediates; and, finally, hopping of oxygen atoms from ligands to the substrate.

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Section: Introductionsupporting

confidence: 93%

First principles analysis of the initial oxidation of Si(001) and Si(111) surfaces terminated with H and CH3

Lin

et al. 2012

The Journal of Chemical Physics

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“…Third, the carrier gas composition could be modified, for example, by adding hydrogen, which can help to suppress the substrate oxidation. Finally, a surface treatment has to be used to create a suitable Si termination, such as hydrogen-terminated Si or (NH 4 ) 2 S x . , However, the long-term stability of common surface terminations is not high …”

Section: Resultsmentioning

confidence: 99%

“…20,26 However, the long-term stability of common surface terminations is not high. 66 Metal deposition with subsequent sulfurization 67 or direct sputtering from metal sulfide targets 27 are other popular ways of growing MoS 2 ; however, they are primarily useful when thick, bulk-like layers are the goal. We point out that a thin SiO 2 layer that was several nanometers thick even formed during sputter deposition of 200 nm thick MoSe 2 films at 400 °C and subsequent annealing at 800 °C.…”

Section: Spatially Resolved Photoemissionmentioning

confidence: 99%

Chemical Vapor Deposition of MoS₂ for Energy Harvesting: Evolution of the Interfacial Oxide Layer

Verhagen

Rodríguez

Vondráček

et al. 2020

ACS Appl. Nano Mater.

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The growth of two-dimensional (2D) materials directly on the substrates that are relevant to device fabrication is crucial for their large-area production and application. This is because their production via transfer processes not only increases the costs but, more importantly, induces contamination and mechanical defects in the transferred material. The presence of a dielectric interface layer and the control of its thickness in transistors and p−n heterojunctions are essential aspects in the semiconductor industry. In the present work, MoS 2 flakes and films with thicknesses down to the monolayer limit were grown using chemical vapor deposition (CVD) on Si substrates covered with a native oxide layer. The high quality of the as-grown MoS 2 resting on a flat SiO 2 surface was documented by a combination of atomic force microscopy, optical spectroscopy, including tip-enhanced photoluminescence spectroscopy, and photoelectron microspectroscopy methods. The changes of the interfacial oxide were then interrogated using spectroscopic imaging ellipsometry and X-ray photoelectron spectroscopy, both with micrometer scale resolution, to show the increase of the oxide layer thickness by several nanometers during the heating and MoS 2 growth processes. Our results evidence the possibility of growing high-quality MoS 2 directly on thin dielectrics. However, at the same time, if this type of MoS 2 deposition is to be used for device fabrication, the simultaneous increase of the SiO 2 thickness makes it important to have proper knowledge and control of the growth process. For the applications in energy harvesting where only a thin (or none) insulating layer is required, alternative growth protocols, surface passivation, or a different dielectric material (e.g., Al 2 O 3 ) are suggested.

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“…Instead of cleavage, a small piece of silicon wafer (B-doped) was etched in a buffered HF solution (mixture of 40% HF and 40% NH 4 F, 1:5) to remove the native oxide. The etching procedure, as reported previously (Kolíbal et al, 2010), passivates the surface so that it remains oxide-free during transport to the XPS or SEM chamber for the plasma treatment. The sample was inserted into the ultrahigh vacuum chamber for XPS analysis within 20 min, which ensured no detectable traces of oxide on a surface.…”

Section: Methodsmentioning

confidence: 99%

Toward Site-Specific Dopant Contrast in Scanning Electron Microscopy

et al. 2014

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Since semiconductor devices are being scaled down to dimensions of several nanometers there is a growing need for techniques capable of quantitative analysis of dopant concentrations at the nanometer scale in all three dimensions. Imaging dopant contrast by scanning electron microscopy (SEM) is a very promising method, but many unresolved issues hinder its routine application for device analysis, especially in cases of buried layers where site-specific sample preparation is challenging. Here, we report on optimization of site-specific sample preparation by the focused Ga ion beam (FIB) technique that provides improved dopant contrast in SEM. Similar to FIB lamella preparation for transmission electron microscopy, a polishing sequence with decreasing ion energy is necessary to minimize the thickness of the electronically dead layer. We have achieved contrast values comparable to the cleaved sample, being able to detect dopant concentrations down to 1×10(16) cm-3. A theoretical model shows that the electronically dead layer corresponds to an amorphized Si layer formed during ion beam polishing. Our results also demonstrate that contamination issues are significantly suppressed for FIB-treated samples compared with cleaved ones.

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Stability of hydrogen-terminated vicinal Si(111) surface under ambient atmosphere

Cited by 16 publications

References 27 publications

First principles analysis of the initial oxidation of Si(001) and Si(111) surfaces terminated with H and CH3

First principles analysis of the initial oxidation of Si(001) and Si(111) surfaces terminated with H and CH3

Chemical Vapor Deposition of MoS₂ for Energy Harvesting: Evolution of the Interfacial Oxide Layer

Toward Site-Specific Dopant Contrast in Scanning Electron Microscopy

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Stability of hydrogen-terminated vicinal Si(111) surface under ambient atmosphere

Cited by 16 publications

References 27 publications

First principles analysis of the initial oxidation of Si(001) and Si(111) surfaces terminated with H and CH3

First principles analysis of the initial oxidation of Si(001) and Si(111) surfaces terminated with H and CH3

Chemical Vapor Deposition of MoS2 for Energy Harvesting: Evolution of the Interfacial Oxide Layer

Toward Site-Specific Dopant Contrast in Scanning Electron Microscopy

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Chemical Vapor Deposition of MoS₂ for Energy Harvesting: Evolution of the Interfacial Oxide Layer