Kinetic model for desorption of hydrogen from amorphous hydrogenated silicon

Khait, Yu. L.; Weil, R.; Beserman, R.; Beyer, W.; Wagner, H.

doi:10.1103/physrevb.42.9000

Cited by 47 publications

(38 citation statements)

References 25 publications

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“…20. In that paper, we studied the dehydrogenation process occurring at the lowest temperature in a-Si: H nanoparticles and compared its kinetics with the results obtained from the desorption experiments reported for a-Si: H thin films by Khait et al 13 Dangling-bond formation energy of 1.05 eV was obtained and the enthalpy of dehydrogenation was around 50 meV/͑H atoms͒ ͑exothermic͒.…”

Section: Introductionmentioning

confidence: 99%

“…We take as reference the low-temperature desorption process already analyzed in a-Si: H films, 13,16 and we consider a first-order reaction kinetics…”

Section: A Identification Of the Dehydrogenation Processesmentioning

confidence: 99%

“…From these experiments and provided that dehydrogenation is not diffusion controlled, the activation energy of Siu H bond breaking can be obtained. The most complete work devoted to this objective is that of Khait et al 13 In their paper, the thermal activation of a lowtemperature peak ͑below 400°C͒, characteristic of lowquality material, is analyzed. They obtain an activation energy of 1.9 eV, consistent with independent experiments on the desorption of hydrogen from the surface of monocrystalline silicon 14 and with theoretical calculations.…”

Section: Introductionmentioning

confidence: 99%

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Calorimetry of dehydrogenation and dangling-bond recombination in several hydrogenated amorphous silicon materials

et al. 2006

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Differential scanning calorimetry ͑DSC͒ was used to study the dehydrogenation processes that take place in three hydrogenated amorphous silicon materials: nanoparticles, polymorphous silicon, and conventional device-quality amorphous silicon. Comparison of DSC thermograms with evolved gas analysis ͑EGA͒ has led to the identification of four dehydrogenation processes arising from polymeric chains ͑A͒, SiH groups at the surfaces of internal voids ͑AЈ͒, SiH groups at interfaces ͑B͒, and in the bulk ͑C͒. All of them are slightly exothermic with enthalpies below 50 meV/͑H atoms͒, indicating that, after dissociation of any SiH group, most dangling bonds recombine. The kinetics of the three low-temperature processes ͓with DSC peak temperatures at around 320 ͑A͒, 360 ͑AЈ͒, and 430°C ͑B͔͒ exhibit a kinetic-compensation effect characterized by a linear relationship between the activation entropy and enthalpy, which constitutes their signature. Their Siu H bond-dissociation energies have been determined to be E͑Siu H͒ 0 = 3.14 ͑A͒, 3.19 ͑AЈ͒, and 3.28 eV ͑B͒. In these cases it was possible to extract the formation energy E͑DB͒ of the dangling bonds that recombine after Siu H bond breaking ͓0.97 ͑A͒, 1.05 ͑AЈ͒, and 1.12 ͑B͔͒. It is concluded that E͑DB͒ increases with the degree of confinement and that E͑DB͒ Ͼ 1.10 eV for the isolated dangling bond in the bulk. After Siu H dissociation and for the low-temperature processes, hydrogen is transported in molecular form and a low relaxation of the silicon network is promoted. This is in contrast to the high-temperature process for which the diffusion of H in atomic form induces a substantial lattice relaxation that, for the conventional amorphous sample, releases energy of around 600 meV per H atom. It is argued that the density of sites in the Si network for H trapping diminishes during atomic diffusion.

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Section: Introductionmentioning

confidence: 99%

“…We take as reference the low-temperature desorption process already analyzed in a-Si: H films, 13,16 and we consider a first-order reaction kinetics…”

Section: A Identification Of the Dehydrogenation Processesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Calorimetry of dehydrogenation and dangling-bond recombination in several hydrogenated amorphous silicon materials

et al. 2006

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“…This is as expected, due to the fact that dehydrogenation is a first-order reaction process. 13,16 So, oxidation will be always triggered at the same temperature. ͑b͒ Oxygen uptake: The amount of oxygen incorporated almost equals the H content ͑Fig.…”

mentioning

confidence: 99%

“…Thus, we propose the following two-step mechanism: ͑step A͒ is based on the widely accepted fact that dehydrogenation of two neighboring Si-H bonds takes place at a low temperature where the simultaneous formation of a H 2 molecule considerably reduces the activation energy of the process. 16 Then, the two dangling bonds left behind offer a highly reactive site for oxygen atoms ready incorporation before substantial dangling bond recombination ͑step B͒.…”

mentioning

confidence: 99%

Enhancement of oxidation rate of a-Si nanoparticles during dehydrogenation

Das

Farjas

Roura

et al. 2001

Applied Physics Letters

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Oxidation of amorphous silicon (a-Si) nanoparticles grown by plasma-enhanced chemical vapor deposition were investigated. Their hydrogen content has a great influence on the oxidation rate at low temperature. When the mass gain is recorded during a heating ramp in dry air, an oxidation process at low temperature is identified with an onset around 250°C. This temperature onset is similar to that of hydrogen desorption. It is shown that the oxygen uptake during this process almost equals the number of hydrogen atoms present in the nanoparticles. To explain this correlation, we propose that oxidation at low temperature is triggered by the process of hydrogen desorption.

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Kinetics of electron induced desorption of hydrogen in nanostructured porous silicon

Ruano

Ferrón

Arce

et al. 2010

Physica Status Solidi (a)

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We found that nanostructured porous silicon obtained by anodization desorbs hydrogen under electron bombardment. The kinetics of this electron-induced effusion can be explained neither in terms of thermal processes nor by direct transference of energy from the impinging electron to the Si-H bonds. We show that short lived-large energy fluctuations (SLEFs), occurring during bimolecular recombination processes of carriers produce both, a midgap increment of the density of electronic defect states and hydrogen desorption.

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Kinetic model for desorption of hydrogen from amorphous hydrogenated silicon

Cited by 47 publications

References 25 publications

Calorimetry of dehydrogenation and dangling-bond recombination in several hydrogenated amorphous silicon materials

Calorimetry of dehydrogenation and dangling-bond recombination in several hydrogenated amorphous silicon materials

Enhancement of oxidation rate of a-Si nanoparticles during dehydrogenation

Kinetics of electron induced desorption of hydrogen in nanostructured porous silicon

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