Hydrogen plasma etching of amorphous and microcrystalline silicon

Oort, R.C. Van; Geerts, M.J.; Heuvel, J.C. van den; Metselaar, J.W.

doi:10.1049/el:19870680

Cited by 19 publications

(5 citation statements)

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“…[17]. Interestingly our results gives some indication on the local growth mechanisms, as the a-Si to mc-Si transition is usually attributed either to an enhancement of the surface diffusion of the SiH x precursors [33] or to a selective etching of the weakly bonded Si atoms [34][35][36][37]. In our case, the increase of the hydrogen content at constant temperature leads to an increase of crystallinity because the selective etching mechanism start to dominate (whereas the surface diffusion remains moderate), while, for constant radical flows, the increase of temperature leads to a strong enhancement of the surface diffusion, leading both to an increase in crystallinity and to a filling of the cracks.…”

Section: Discussionmentioning

confidence: 60%

Microcrystalline silicon solar cells: effect of substrate temperature on cracks and their role in post‐oxidation

Python

Dominé

Söderström

et al. 2010

Progress in Photovoltaics

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Microcrystalline silicon (mc-Si:H) cells can reach efficiencies up to typically 10% and are usually incorporated in tandem micromorph devices. When cells are grown on rough substrates, ''cracks'' can appear in the mc-Si:H layers. Previous works have demonstrated that these cracks have mainly detrimental effects on the fill factor and open-circuit voltage, and act as bad diodes with a high reverse saturation current. In this paper, we clarify the nature of the cracks, their role in postoxidation processes, and indicate how their density can be reduced. Regular secondary ion mass spectrometry (SIMS) and local nano-SIMS measurements show that these cracks are prone to local post-oxidation and lead to apparent high oxygen content in the layer. Usually the number of cracks can be decreased with an appropriate modification of the substrate surface morphology, but then, the required light scattering effect is reduced due to a lower roughness. This study presents an alternative/complementary way to decrease the crack density by increasing the substrate temperature during deposition. These results, also obtained when performing numerical simulation of the growth process, are attributed to the enhanced surface diffusion of the adatoms at higher deposition temperature. We evaluate the cracks density by introducing a fast method to count cracks with good statistics over approximately 4000 mm of sample cross-section. This method is proven to be useful to quickly visualize the impact of substrate morphology on the density of cracks in microcrystalline and in micromorph devices, which is an important issue in the manufacturing process of modules.

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Section: Discussionmentioning

confidence: 60%

Microcrystalline silicon solar cells: effect of substrate temperature on cracks and their role in post‐oxidation

Python

Dominé

Söderström

et al. 2010

Progress in Photovoltaics

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“…A motivation for longer H 2 plasma treatments is to use them for a-Si:H etching (rather than merely for passivation improvement). [11][12][13] Indeed, advanced device architectures such as SHJ back-contacted solar cells require doped a-Si:H layer patterning, while preserving pristine a-Si:H(i) underlayers for surface passivation and thus the high V OC s typical for SHJ devices. [14][15][16] A clear advantage of dry etching for the fabrication of SHJ back-contacted solar cells is that both etching and deposition can take place in the same system without vacuum break.…”

mentioning

confidence: 99%

Amorphous/crystalline silicon interface defects induced by hydrogen plasma treatments

Geissbühler¹,

Wolf²,

Demaurex³

et al. 2013

Applied Physics Letters

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Excellent amorphous/crystalline silicon interface passivation is of extreme importance for high-efficiency silicon heterojunction solar cells. This can be obtained by inserting hydrogen-plasma treatments during deposition of the amorphous silicon passivation layers. Prolonged hydrogen-plasmas lead to film etching. We report on the defect creation induced by such treatments: A severe drop in interface-passivation quality is observed when films are etched to a thickness of less than 8 nm. Detailed characterization shows that this decay is due to persistent defects created at the crystalline silicon surface. Pristine interfaces are preserved when the post-etching film thickness exceeds 8 nm, yielding high quality interface passivation.

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“…Consecutively, hydrogen is introduced into the reaction chamber and the plasma etching is started. As already reported in the literature, 28,29 the hydrogen plasma leads to etching of the silicon substrate. Etching is only prevented where the catalyst particles cover the substrate.…”

Section: Resultsmentioning

confidence: 66%

“…Their formation is a result of the hydrogen plasma etching of the silicon substrate as already reported by other groups. 28,29 Since the cones are covered either by large catalyst particles or by CNFs, respectively, these areas of the substrate are not affected by the etching.…”

Section: Resultsmentioning

confidence: 99%

Silicon carbide embedded in carbon nanofibres: structure and band gap determination

Minella

Pohl

Täschner

et al. 2014

Phys. Chem. Chem. Phys.

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Materials drastically alter their electronic properties when being reduced to the nanoscale due to quantum effects. Concerning semiconductors, the band gap is expected to broaden as a result of the quantum confinement. In this study we report on the successful synthesis of wide bandgap SiC nanowires (with great potential for applications) and the local determination of their band gap. Their value was found to be higher with respect to bulk SiC. The nanowires are grown as a heterostructure, i.e. encapsulated in carbon nanofibres via dc hot-filament Plasma-Enhanced Chemical Vapour Deposition on the Si/SiO2 substrate. The structure of the as-produced carbon nanofibres was characterized by means of aberration-corrected high-resolution transmission electron microscopy. Two different pure SiC polytypes, namely the 3C (cubic) and the 6H (hexagonal) as well as distorted structures are observed. The SiC nanowires have diameters in the range of 10-15 nm and lengths of several hundred nanometers. The formation of the SiC is a result of the substrate etching during the growth of the CNFs and a subsequent simultaneous diffusion of not only carbon, but also silicon through the catalyst particle.

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Hydrogen plasma etching of amorphous and microcrystalline silicon

Cited by 19 publications

References 1 publication

Microcrystalline silicon solar cells: effect of substrate temperature on cracks and their role in post‐oxidation

Microcrystalline silicon solar cells: effect of substrate temperature on cracks and their role in post‐oxidation

Amorphous/crystalline silicon interface defects induced by hydrogen plasma treatments

Silicon carbide embedded in carbon nanofibres: structure and band gap determination

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