Light-induced dangling bonds in hydrogenated amorphous silicon

Dersch, H.; Stuke, J.; Beichler, J.

doi:10.1063/1.92402

Cited by 473 publications

(95 citation statements)

References 9 publications

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“…The aforementioned highquality, dense material is thus characterized by a low nanostructure parameter R * . The electronic defects in the bulk have been investigated very intensively and they are traditionally viewed as isolated dangling bonds (DBs) which appear as coordination defects (in a continuous random network 13 ) that have direct control over midgap states, 14,15 have a paramagnetic nature, [16][17][18] and can be converted into weak bonds such that they also impact the tail states. [19][20][21][22] An alternative view on the nanostructure that has been attracting attention in recent years also considers isolated dangling bonds, but additionally takes defects in open volume deficiencies into consideration.…”

Section: Introductionmentioning

confidence: 99%

Correlating the silicon surface passivation to the nanostructure of low-temperature a-Si:H after rapid thermal annealing

Macco

Melskens

Podraza³

et al. 2017

Journal of Applied Physics

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Using an inductively coupled plasma, hydrogenated amorphous silicon (a-Si:H) films have been prepared at very low temperatures (<50 °C) to provide crystalline silicon (c-Si) surface passivation. Despite the limited nanostructural quality of the a-Si:H bulk, a surprisingly high minority carrier lifetime of ∼4 ms is demonstrated after a rapid thermal annealing treatment. Besides the excellent level of surface passivation, the main advantage of the low-temperature approach is the facile suppression of undesired epitaxial growth. The correlation between the a-Si:H nanostructure and the activation of a-Si:H/c-Si interface passivation, upon annealing, has been studied in detail. This yields a structural model that qualitatively describes the different processes that take place in the a-Si:H films during annealing. The presented experimental findings and insights can prove to be useful in the further development of very thin a-Si:H passivation layers for use in silicon heterojunction solar cells.

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Section: Introductionmentioning

confidence: 99%

Correlating the silicon surface passivation to the nanostructure of low-temperature a-Si:H after rapid thermal annealing

Macco

Melskens

Podraza³

et al. 2017

Journal of Applied Physics

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“…24,25 Another classic example is the LID of thin-film a-Si:H solar cells. The latter is usually attributed to the generation of deep defects that act as recombination centers, 26 and is commonly referred to as the Staebler-Wronski effect (SWE). [27][28][29][30][31] Crystalline Si surfaces coated with intrinsic a-Si:H films were found to suffer as well from a degradation in surface passivation during prolonged light soaking (LS).…”

mentioning

confidence: 99%

Light-induced performance increase of silicon heterojunction solar cells

Kobayashi

Wolf

Levrat

et al. 2016

Applied Physics Letters

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Silicon heterojunction solar cells consist of crystalline silicon (c-Si) wafers coated with doped/intrinsic hydrogenated amorphous silicon (a-Si:H) bilayers for passivating-contact formation. Here, we unambiguously demonstrate that carrier injection either due to light soaking or (dark) forward-voltage bias increases the open circuit voltage and fill factor of finished cells, leading to a conversion efficiency gain of up to 0.3% absolute. This phenomenon contrasts markedly with the light-induced degradation known for thin-film a-Si:H solar cells. We associate our performance gain with an increase in surface passivation, which we find is specific to doped a-Si:H/c-Si structures. Our experiments suggest that this improvement originates from a reduced density of recombination-active interface states. To understand the time dependence of the observed phenomena, a kinetic model is presented.

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“…Moreover, the conduction electrons from the crystalline phase are likely to screen the LRPF. Since E Q is related to the width of LRPF through Equation (6), E Q appears to be a measure of heterogeneities and disorder.…”

Section: Lrpf As a Function Of χmentioning

confidence: 99%

“…It is known, for example, that the creation of dangling bonds is one of the main outcomes of the degradation. 6 Since Si has a highly over coordinated network, there are many strained Si-Si and Si-H weak bonds, which break upon exposure to light, giving defects including dangling bonds. In 1994, it was reported 7 that a-Si:H cells containing small crystallites of silicon (nc-Si:H), did not show the SWE.…”

Section: Introductionmentioning

confidence: 99%

Light induced degradation of amorphous silicon containing nanocrystalline silicon

2014

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The effect of light soaking (LS) is studied in hydrogenated amorphous silicon (a-Si:H) containing different amounts of nanocrystals, prepared by varying the deposition conditions in a plasma enhanced chemical vapor deposition (PECVD) system. We find that the presence of nanocrystals (nc-Si) stabilizes the a-Si:H against LS. The long range potential fluctuations (LRPF) are measured and we find that they become smaller as the fraction of nanocrystals (χ) in the films increases. Raman spectra show a peak at 490 cm−1, which is taken to be the result of Intermediate Range Order (IRO) in the films. This IRO peak appears just when the hydrogen dilution is sufficiently high for the crystallization to begin, and increases with increasing hydrogen dilution as the crystallization increases. In contrast LRPF have maximum width when χ is zero and it decreases as χ increases. Further, the degradation upon LS is negligible when χ > 25%. We suggest an alternative mechanism for the improved stability, in which the photogenerated carriers moving under the influence of the long range potential fluctuations have a propensity to go to nc-Si, and recombine in that region.

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Light-induced dangling bonds in hydrogenated amorphous silicon

Cited by 473 publications

References 9 publications

Correlating the silicon surface passivation to the nanostructure of low-temperature a-Si:H after rapid thermal annealing

Correlating the silicon surface passivation to the nanostructure of low-temperature a-Si:H after rapid thermal annealing

Light-induced performance increase of silicon heterojunction solar cells

Light induced degradation of amorphous silicon containing nanocrystalline silicon

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