Substantially low desorption barriers in recombinative desorption of deuterium from a Si(1 0 0) surface

Kihara, Y.; Inanaga, S.; Namiki, A.

doi:10.1016/j.susc.2009.01.038

Cited by 14 publications

(7 citation statements)

References 36 publications

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“…1 is somewhat different from the above formulation of SiH 3 -induced. It is generally accepted that thermal desorption of hydrogen will occur in molecular form [12], leaving two dangling bonds at surface. (They seem to form some kind of weak bonding so that the hydrogen desorption is energetically favored.)…”

Section: Discussionmentioning

confidence: 99%

Origin of Pseudo Second Order Reaction in a-Si:H Growth

Toyoshima

2017

e-J. Surf. Sci. Nanotech.

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It is generally accepted that a pair of SiH3 radicals are responsible for the film growth reactions of hydrogenated amorphous silicon, namely a first SiH3 radical to pick up surface-terminating H leaving active site on the growing surface, and a second SiH3 to stick there. Since the first reaction step is rate determining, the film growth rate is proportional (1st order) to the SiH3 density. However, in some case, 2nd order dependence on SiH3 density is reported, especially when the film growth rate (and thus the SiH3 density) is quite low. This funny behavior contradicts the general concept that a higher order reaction will take place when the number density of the concerning species is high. In this report, a detailed analysis of these growth reactions based on the method of steady state is given to prevail that the origin of such a pseudo 2nd order dependence is clearly explained by introducing the reverse reaction to the first step that determines the growth rate. In addition, discussion is presented to show that such a reverse reaction is plausible.

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Section: Discussionmentioning

confidence: 99%

Origin of Pseudo Second Order Reaction in a-Si:H Growth

Toyoshima

2017

e-J. Surf. Sci. Nanotech.

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“…It must, however, be pointed out that the schematization of the hydrogen desorption process in terms of the four reactions sketched in Figure 1 is simplistic as the overall process dynamics, in particular if a reactive gas phase is present, can in general be influenced by other surface processes, such as the diffusion of adatoms, and by the surface coverage. Some recent experimental10 and theoretical11 advances in the study of the hydrogenated surface dynamics have been published recently.…”

Section: Introductionmentioning

confidence: 99%

Reactivity of Silicon Surfaces in the Presence of Adsorbed Hydrogen and Chlorine

Cavallotti¹

2010

Chemical Vapor Deposition

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The desorption of hydrogen and hydrogen chloride from Si surfaces is the rate-determining step of the low temperature CVD of silicon from both hydrogenated and chlorinated precursors. Thus, in order to model the deposition process, the rate of these reactions must be known to a high level of accuracy. In this work, the surface desorption kinetics of H 2 and HCl from the Si(100)2 T 1 surface is investigated by modeling the surface through clusters of various dimensions (up to 60 Si atoms) and determining the reaction energies at the B3LYP, and coupled cluster methodology with inclusion of single, double and a perturbative estimation of triple excitations (CCSD(T)) levels. The investigated mechanisms are the pairwise intradimer and the 4H-2H reaction pathways. The desorption activation energy (57.4 kcal mol À1 ) and adsorption barriers (15.9 kcal mol À1 ) calculated for H 2 for the 4H and 2H pathways are in good agreement with experimental data, confirming that these are the H 2 main desorption and adsorption routes. The reaction mechanism of HCl is different to that of H 2 . The calculations in fact indicate that the less activated desorption pathway (65.0 kcal mol À1) is the intradimer mechanism, followed by the 2H pathway (67.1 kcal mol À1 ), which might thus compete with the intradimer pathway at low surface coverage. The HCl adsorption barrier on Si dimers is small (0.6 À 4.8 kcal mol À1), confirming the high reactivity of HCl with Si surfaces.

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“…The hydrogenation of semiconductor surfaces is a topic of great interest, [1][2][3][4][5][6][7][8][9][10] The interaction of hydrogen with semiconductor surfaces generally induces important structural and electronic changes. In general, adsorption of hydrogen produces passivation of the surface; the hydrogen atoms attach to the semiconductor dangling bonds, forming strong chemical bonds ͑chemical passivation͒ and removing electronic states from the semiconductor gap ͑electronic passivation͒.…”

Section: Introductionmentioning

confidence: 99%

Hydrogenation of semiconductor surfaces: Si-terminated cubic SiC(100) surfaces

Trabada

Ortega

2009

Phys. Rev. B

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We analyze the hydrogenation of the Si-terminated surfaces 3C-SiC͑100͒-3 ϫ 2 and 3C-SiC͑100͒-c͑4 ϫ 2͒ using density-functional-theory techniques. For the Si-rich 3 ϫ 2 case, after saturation of the Si dangling bonds, hydrogen atoms break Si-Si bonds between atoms in the first two layers, replacing them by Si-H bonds, up to a hydrogen adsorption of eight hydrogen atoms per 3 ϫ 2 unit cell, with the formation of SiH 3 groups on the surface. At higher hydrogen adsorptions Si-H bonds replace also Si-Si bonds between second-and third-layer Si atoms. We find that all the stable structures as a function of the hydrogen chemical potential are insulating and propose that the observed hydrogen-induced metallization of the Si-rich SiC͑100͒-3 ϫ 2 surface is related to the dynamical equilibrium between adsorption and abstraction of hydrogen atoms close to the point where hydrogen atoms start to break Si-Si bonds. We also find that desorption of SiH 4 molecules is not energetically favorable until values of the hydrogen chemical potential above half the energy of the H 2 molecule. Regarding the Si-poor c͑4 ϫ 2͒ surface, our results show that the hydrogenated H / SiC͑100͒-2 ϫ 1 surface corresponds to a monohydride surface with a Si coverage of one monolayer above the last C layer.

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Substantially low desorption barriers in recombinative desorption of deuterium from a Si(1 0 0) surface

Cited by 14 publications

References 36 publications

Origin of Pseudo Second Order Reaction in a-Si:H Growth

Origin of Pseudo Second Order Reaction in a-Si:H Growth

Reactivity of Silicon Surfaces in the Presence of Adsorbed Hydrogen and Chlorine

Hydrogenation of semiconductor surfaces: Si-terminated cubic SiC(100) surfaces

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