Hydrogen desorption kinetics from monohydride and dihydride species on silicon surfaces

Gupta, Pawan; Colvin, Vicki L.; George, Steven M.

doi:10.1103/physrevb.37.8234

Cited by 575 publications

(285 citation statements)

References 49 publications

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“…hydrogen adsorption does not lead to the breaking If it is assumed that the adsorption of H leads of dimer bonds (at least not at the partial presto the breaking of the total dimer bond, the above sures of atomic hydrogen considered in this paper), basic adsorption enthalpy of -338 kJ mol 1 has only the ir-bond will be broken. This is consistent to be reduced with the total reconstruction energy with the results of several recent surface studies plus hSISlH; the hS~s~H term arises because the [41][42][43][44][45].Even when the Si(001)-(2 x 1) surface is subjected to high amounts of atomic hydrogen, cess d would always be 184 kJ mol 1 (i.e. the total not all of the surface dimers are broken [46].…”

Section: Single-bound Speciessupporting

confidence: 72%

A theoretical study of adsorption equilibria in silicon CVD

Gardeniers

Giling

Jong

et al. 1990

Journal of Crystal Growth

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As part of a theoretical study of adsorption processes in the chemical vapour deposition of silicon, thermochemical data are derived for the adsorption of Si-H species on the Si(111) and the dimer-reconstructed Si(001)-(2 xl) surfaces. Essential contributions to the heats of adsorption appear to be electron pairing and two-and three-body interactions. It is shown that when the bond energies are defined in this way, also a consistent description of the bonds in silicon hydrides is provided. This demonstrates that with reasonable confidence the method can be applied to the adsorption process itself. Data are derived for species which may form one, two or even four bonds with the surface. It is assumed that on the (111) surface adsorbates bind on the "dangling bonds" which are present on this surface in a broken bond model. It is demonstrated that on the dimer reconstructed Si(001)-(2 xl) surface, adsorbates will either bind on the surface atoms with one or two bonds, without the breaking of the dimer bonds, or, if the species have the possibility to form two or four bonds with the surface atoms, may become inserted into the dimer bonds. With the aid of the derived thermochemical data for adsorption and the Langmuir isotherm or modifications thereof, the coverage of the Si(111) and the dimer reconstructed Si(001)-(2X1) surfaces with species from the Si-H system is calculated. It is found that the equilibrium surface coverages of the Si(111) and the Si(001)-(2 xl) surfaces are very similar: the hydrogen coverage is high at all temperatures, while at low supersaturation the coverage with growth species is very low on both surfaces.

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Section: Single-bound Speciessupporting

confidence: 72%

A theoretical study of adsorption equilibria in silicon CVD

Gardeniers

Giling

Jong

et al. 1990

Journal of Crystal Growth

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“…Due to its thermal stability, surface monohydride is reported to require temperatures above 550 • C for its removal. [36] Hydrogen trapped internally by point defects within the skeleton could need temperatures as high as 700 • C [37]. For this reason, samples were oxidized at 700 • C for a long duration and, at least by FTIR, silicon-hydride was reduced to undetectable levels (see Fig.…”

Section: Discussionmentioning

confidence: 99%

Quantification and Reduction of the Residual Chemical Reactivity of Passivated Biodegradable Porous Silicon for Drug Delivery Applications

Shabir¹,

Webb²,

Nadarassan³

et al. 2017

Silicon

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The chemical reactivity of as-anodized porous silicon is shown to have an adverse effect on a model drug (Lansoprazole) loaded into the pores. The silicon hydride surfaces can cause unwanted reactions with actives during storage or use. Techniques such as thermal oxidation or surface derivatization can lower the reactivity somewhat, by replacing the reactive silicon-hydride species with a more benign oxide or functional group. However, by using a trio of analytical techniques (fluorometric dye assay, HPLC assay, and chemography) we show that residual hydride is still likely to be present and only after combining thermal oxidation with surface derivatization can the residual reactivity be reduced to those values typically observed with sol-gel (porous) silica. Potential sources of residual reactivity are discussed, with reference to data obtained by trace metal analysis, residual solvents, and pH measurements.

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“…Moreover, surface oxides and nitrides act as efficient permeation barriers [192][193][194] . Hydrogen bound on the silicon surface has very high desorption energy 226,227 (above 1.8 eV) such that the desorption rate from one monolayer coverage would be below 10 −22 mbar l s −1 cm −2 using Equation 11. Thermal desorption studies 227 show that most hydrogen complexes can be desorbed from silicon by annealing at 600 • C.…”

Section: Hydrogenmentioning

confidence: 99%

“…immersion into water). We have calculated the rate for silicon using a summation of diffusion (Equation 12) from the bulk as well as considering the higher concentration at the surface (see text), and also recombination-limited surface desorption using Equation 11 (k = 2) with values from Gupta et al 227 . The room temperature silicon outgassing shows an initially high rate due to diffusion of the high concentration near the surface and is eventually limited by surface desorption of the dihydride surface species (as are the higher temperature bakes).…”

Section: Carbon Monoxidementioning

confidence: 99%

Contributed Review: The feasibility of a fully miniaturized magneto-optical trap for portable ultracold quantum technology

Rushton

Aldous

Himsworth

2014

Review of Scientific Instruments

107

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Experiments using laser cooled atoms and ions show real promise for practical applications in quantumenhanced metrology, timing, navigation, and sensing as well as exotic roles in quantum computing, networking and simulation. The heart of many of these experiments has been translated to microfabricated platforms known as atom chips whose construction readily lend themselves to integration with larger systems and future mass production. To truly make the jump from laboratory demonstrations to practical, rugged devices, the complex surrounding infrastructure (including vacuum systems, optics, and lasers) also needs to be miniaturized and integrated. In this paper we explore the feasibility of applying this approach to the Magneto-Optical Trap; incorporating the vacuum system, atom source and optical geometry into a permanently sealed microlitre system capable of maintaining 10 −10 mbar for more than 1000 days of operation with passive pumping alone. We demonstrate such an engineering challenge is achievable using recent advances in semiconductor microfabrication techniques and materials.PACS numbers: 07.07.Df, 37.10.Gh, 07.30.Kf, I. ULTRACOLD QUANTUM TECHNOLOGYSince the first demonstrations of atoms and ions at sub-millikelvin temperatures in the mid-1980s, the field of atomic physics has been revolutionized by laser cooling and trapping as it provides researchers with a method to probe some of the purest and sensitive quantum systems available. This field is still highly productive and recently has put significant emphasis on the practical applications of this technology beyond the laboratory 1,2 . It was evident very early on that ultracold matter would be an indispensable tool in precise timing applications and a recent demonstration 3 has shown extremely low instabilities at the 10 −18 level. The wavelike nature of atoms as they are cooled to lower temperatures can be used to form atomic interferometers that outperform optical counterparts in measurements of accelerated reference frames 4-7 , which are important for inertial guidance systems, but can also provide sensitive measurements of mass, charge and magnetic fields [8][9][10][11] . Greater sensitivity beyond the classical limit is possible via squeezed 12 and entangled states 13-15 , which are also fundamental attributes for quantum computing 16,17 , and long distance quantum networking 18 . Ultracold matter has been used in the emerging field of quantum simulation 19 and is an indispensable tool in determining fundamental constants 20 , testing general relativity 21 and defining measurement standards 22 . Many researchers and industries believe such tools will be a major part of the 'second quantum revolution' in which the more 'exotic' properties of quantum physics are applied for practical applications 23,24 .The field of ultracold matter has reached a matua) m.d.himsworth@soton.ac.uk rity in both experimental methods and theoretical understanding allowing experiments to begin leaving the laboratory 25-27 . These systems are bespoke, rarely take up a ...

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Hydrogen desorption kinetics from monohydride and dihydride species on silicon surfaces

Cited by 575 publications

References 49 publications

A theoretical study of adsorption equilibria in silicon CVD

A theoretical study of adsorption equilibria in silicon CVD

Quantification and Reduction of the Residual Chemical Reactivity of Passivated Biodegradable Porous Silicon for Drug Delivery Applications

Contributed Review: The feasibility of a fully miniaturized magneto-optical trap for portable ultracold quantum technology

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