A computational study on the adsorption configurations and reactions of SiHx(x = 1-4) on clean and H-covered Si(100) surfaces

Le, Thong Nguyen-Minh; Raghunath, P.; Huynh, Lam K.; Lin, Ming‐Chang

doi:10.1016/j.apsusc.2016.06.099

Cited by 4 publications

(7 citation statements)

References 44 publications

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“…We separate the first growth stage and second growth stage: in the first growth stage, gaseous species interact with a clean Si(100) surface without any hydrogen atoms. As a premise, a previous DFT study reported SiH 3 and SiH 2 radicals chemisorbed on a clean Si(100) surface without any energy barriers . We actually found that most radicals were observed to be chemisorbed on the surface.…”

Section: Resultssupporting

confidence: 60%

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Reactive Force Field Molecular Dynamics Study of the Effects of Gaseous Species on the Composition and Crystallinity of Silicon–Germanium Thin Films

Uene

Mabuchi

Zaitsu

et al. 2023

Crystal Growth & Design

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We simulated the growth of a silicon–germanium (SiGe) film using reactive force field molecular dynamics (ReaxFF MD) in combinations of SiH3, SiH2, GeH3, and GeH2 radicals to evaluate the effects of gaseous species on thin-film composition and crystallinity and to understand the growth mechanisms. The film compositions could be estimated in these combinations because of the linear increase in the Ge content of the films. The average crystallinity grown by SiH3 was higher than that by SiH2 radicals. The crystallinity of the film grown by SiH3 radicals tends to be drastically decreased by GeH2 radicals. The growth mechanisms for XH3 and XH2 (X = Si or Ge) radicals were compared. XH3 radicals abstracted surface H atoms, and then more XH3 radicals chemisorbed onto the formed dangling bonds, resulting in film growth through a two-step reaction known as the Eley–Rideal-type (ER-type) mechanism. The ER-type mechanism grows the film with a low hydrogen content and high crystallinity. In contrast, XH2 radicals displayed not only the ER-type mechanism but also a one-step reaction, the H-capturing mechanism, which incorporates surface H atoms into the gaseous species. The H-capturing mechanism results in film growth with high hydrogen content and low crystallinity. The growth mechanisms are influenced by high/low H-coverage. The surface H atoms thermally move around the bonded atoms and give their kinetic energy to the diffusing gaseous species. Excess surface H atoms promote desorption. Our results from the ReaxFF MD suggested experimental settings and conditions that would enable the growth of high-quality films. Our results also suggested that SiH3 and GeH3 radicals should be mainly generated in the gas phase for high-quality SiGe film growth.

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Section: Resultssupporting

confidence: 60%

“…As a premise, a previous DFT study reported SiH 3 and SiH 2 radicals chemisorbed on a clean Si(100) surface without any energy barriers. 65 We actually found that most radicals were observed to be chemisorbed on the surface.…”

Section: Key Reactions and Growthmentioning

confidence: 93%

Reactive Force Field Molecular Dynamics Study of the Effects of Gaseous Species on the Composition and Crystallinity of Silicon–Germanium Thin Films

Uene

Mabuchi

Zaitsu

et al. 2023

Crystal Growth & Design

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“…In Figures 1 and 2, the H-covered Si surface is the most stable when the H atoms gather together. In fact, according to Le et al [22], the mechanism for a partially H-covered Si (100) surface was similar but was characterized by higher adsorption energies in most cases. This implies that the presence of hydrogen atoms on the surface stabilizes the surface species.…”

Section: Comparisons Of Si 2 H 6 Surface Reactivitiesmentioning

confidence: 89%

“…Recently, Le et al [22] claimed that the adsorption energy of the SiH 4 molecule is higher on a H-covered Si(001) surface than on a clean Si(001) surface, and suggested that the surface species may become more stable in the presence of hydrogen. Unfortunately, their study did not take into account the surface reactivity of Si 2 H 6 , which is a highly important precursor for improving the throughput of Si deposition especially when using PECVD at intermediate pressure.…”

Section: Introductionmentioning

confidence: 99%

Theoretical Analysis of Si2H6 Adsorption on Hydrogenated Silicon Surfaces for Fast Deposition Using Intermediate Pressure SiH4 Capacitively Coupled Plasma

Park

Kim

2021

Coatings

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The rapid and uniform growth of hydrogenated silicon (Si:H) films is essential for the manufacturing of future semiconductor devices; therefore, Si:H films are mainly deposited using SiH4-based plasmas. An increase in the pressure of the mixture gas has been demonstrated to increase the deposition rate in the SiH4-based plasmas. The fact that SiH4 more efficiently generates Si2H6 at higher gas pressures requires a theoretical investigation of the reactivity of Si2H6 on various surfaces. Therefore, we conducted first-principles density functional theory (DFT) calculations to understand the surface reactivity of Si2H6 on both hydrogenated (H-covered) Si(001) and Si(111) surfaces. The reactivity of Si2H6 molecules on hydrogenated Si surfaces was more energetically favorable than on clean Si surfaces. We also found that the hydrogenated Si(111) surface is the most efficient surface because the dissociation of Si2H6 on the hydrogenated Si(111) surface are thermodynamically and kinetically more favorable than those on the hydrogenated Si(001) surface. Finally, we simulated the SiH4/He capacitively coupled plasma (CCP) discharges for Si:H films deposition.

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“…The absolute atomic hydrogen densities were determined through calibration of H-atom fluorescence signal intensities with TALIF measurements on Kr atoms, introduced independently in the same reactor at a known pressure [28]. For these calibration measurements, the laser excitation wavelength was tuned to the Kr 4p 6 1 S 0 → 5p ′ [3/2] 2 at 204.13 nm, and the fluorescence signal at 587.09 nm was observed using an interferential filter centred at 586 nm (Semrock FF02-586/15-25) in front of the streak camera.…”

Section: Experimental Details and Measurementsmentioning

confidence: 99%

Depopulation mechanisms of atomic hydrogen in the n = 3 level following two-photon excitation by a picosecond laser

Duluard,

Invernizzi,

Hassouni

et al. 2024

Plasma Sources Sci. Technol.

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One of the major constraints of measurements of atomic hydrogen densities using Two-Photon Absorption Laser Induced Fluorescence (TALIF) in most plasma and combustion environments is the determination of fluorescence decay times (τfluo H), especially when using nanosecond-lasers or slow acquisition systems. Therefore, it is necessary to identify the depopulation processes of the laser excited level in order to correctly estimate τfluo H. In this study, depopulation mechanisms of atomic hydrogen excited by two-photon absorption to the n=3 level (H(n=3)) have been investigated using a picosecond-laser excitation and acquisition of fluorescence by a streak camera, which allowed for direct measurement of τfluo H and hence, the atomic hydrogen densities, in a H2 microwave plasma operating in the pressure range 20 – 300 Pa. By combining these measurements with a detailed H(n=3) collisional radiative depopulation model, it was found that full mixing amongst the H(n=3) sub-levels occurs in our discharge conditions, even at a pressure as low as 20 Pa. Moreover, it is also seen that the Lyman β line is only partially trapped, as its escape factor Λ31 decreases from 0.94 – 0.98 down to 0.58 – 0.86 while the measured atomic hydrogen density rises from 8±5×1019 m-3 to 9±6×1020 m-3. This means that the radiative decay rate of H(n=3) atoms varies with pressure and the classical Stern-Volmer method used to determine the quenching cross-section of excited H(n=3) in collisions with H2 molecules, σQ H(n=3)/H2, is not valid for our measurements. We used two different physics-based approaches, and show that the quenching cross-section σQ H(n=3)/H2 lies in the range 90 – 106×10-20 m2, which can be averaged as 98±8×10-20 m2. This substantially improved estimation of σQ H(n=3)/H2 obtained in this work will be useful for the accurate estimation of H(n=3) fluorescence decay times and therefore the atomic hydrogen densities.

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A computational study on the adsorption configurations and reactions of SiHx(x = 1-4) on clean and H-covered Si(100) surfaces

Cited by 4 publications

References 44 publications

Reactive Force Field Molecular Dynamics Study of the Effects of Gaseous Species on the Composition and Crystallinity of Silicon–Germanium Thin Films

Reactive Force Field Molecular Dynamics Study of the Effects of Gaseous Species on the Composition and Crystallinity of Silicon–Germanium Thin Films

Theoretical Analysis of Si2H6 Adsorption on Hydrogenated Silicon Surfaces for Fast Deposition Using Intermediate Pressure SiH4 Capacitively Coupled Plasma

Depopulation mechanisms of atomic hydrogen in the n = 3 level following two-photon excitation by a picosecond laser

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