Characterization of Ultra-thin μc-Si:H Films for Silicon Heterojunction Solar Cells

Wernerus, Holger; Bivour, Martin; Kroely, Laurent; Hermle, Martin; Wolke, W.

doi:10.1016/j.egypro.2014.08.092

Cited by 14 publications

(17 citation statements)

References 22 publications

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“…The crystallinity determined from ellipsometry fitting, however, appears to be almost binary, as it jumps from near zero for most films to above 60% for the films that are 24 and 84 nm thick. This, in part, reflects the difficulty of finding low-mean-square-error fits, even when using the same model for mc-Si:H reported by Wernerus et al [9]. Using the Raman crystallinity in the ellipsometry fittingeither as an initial guess or as a fixed parameter for the top 13 nmimproved the error somewhat, and at least yielded layer thicknesses consistent with TEM and known deposition rates.…”

Section: Resultsmentioning

confidence: 94%

“…Raman spectroscopy and ellipsometry are the quickest methods because a change in wavelength or polarization reveals information about the sample in as short as seconds, making the methods also excellent candidates for in situ study or for use in manufacturing quality control. Wernerus et al demonstrated that spectroscopic ellipsometry can – with the proper models – provide an estimate of the volume‐averaged crystallinity of silicon films, though this technique was validated with only three data points . In addition, most ellipsometers are not capable of measuring textured samples, which is important for solar cell applications.…”

Section: Introductionmentioning

confidence: 99%

“…demonstrated that spectroscopic ellipsometry canwith the proper modelsprovide an estimate of the volume-averaged crystallinity of silicon films, though this technique was validated with only three data points [9]. In addition, most ellipsometers are not capable of measuring textured samples, which is important for solar cell applications.…”

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confidence: 99%

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Substrate‐independent analysis of microcrystalline silicon thin films using UV Raman spectroscopy

Carpenter

Bailly

Boley³

et al. 2017

Physica Status Solidi (b)

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Surface‐sensitive UV Raman spectroscopy is used to analyze the crystallinity of silicon films less than 20 nm thick directly on silicon wafers. The 325‐nm excitation has a Raman detection thickness of only 13 nm within the silicon film, thus eliminating signal from the substrate. We demonstrate measured crystallinities of microcrystalline silicon thin films that are consistent with the microstructure observed in transmission electron microscopy. Comparison is also made to ellipsometry, which is less able to accurately determine crystallinity than UV Raman spectroscopy. The UV Raman approach is particularly useful for layers grown on substrates of the same material but with different microstructure, and can be extended to non‐silicon materials.

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Section: Resultsmentioning

confidence: 94%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Substrate‐independent analysis of microcrystalline silicon thin films using UV Raman spectroscopy

Carpenter

Bailly

Boley³

et al. 2017

Physica Status Solidi (b)

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“…The layers were characterized by spectroscopic ellipsometry (SE, HORIBA Jobin Yvon, UVISEL) fitting the data using a model similar to the one described in [48]. Furthermore, Raman spectroscopy [1) Renishaw RAMASCOPE, green laser at 514 nm, and 2) Renishaw InVia REXLEX, UV laser at 325 nm] was used for layer characterization.…”

Section: Methodsmentioning

confidence: 99%

Strategies for Doped Nanocrystalline Silicon Integration in Silicon Heterojunction Solar Cells

Seif

Descoeudres

Nogay

et al. 2016

IEEE J. Photovoltaics

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Carrier collection in silicon heterojunction (SHJ) solar cells is usually achieved by doped amorphous silicon layers of a few nanometers, deposited at opposite sides of the crystalline silicon wafer. These layers are often defect-rich, resulting in modest doping efficiencies, parasitic optical absorption when applied at the front of solar cells, and high contact resistivities with the adjacent transparent electrodes. Their substitution by equally thin doped nanocrystalline silicon layers has often been argued to resolve these drawbacks. However, low-temperature deposition of highly crystalline doped layers of such thickness on amorphous surfaces demands sophisticated deposition engineering. In this paper, we review and discuss different strategies to facilitate the nucleation of nanocrystalline silicon layers and assess their compatibility with SHJ solar cell fabrication. We also implement the obtained layers into devices, yielding solar cells with fill factor values of over 79% and efficiencies of over 21.1%, clearly underlining the promise this material holds for SHJ solar cell applications.Index Terms-Microcrystalline silicon, nanocrystalline silicon, silicon heterojunctions (SHJs), solar cells.

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“…80 Recent PCE improvements have consequently come from implementing the more complex IBC design, which places both contacts on the rear side of the cell, removing both the TCO and doped a-Si:H from the sun-facing side of the device. 17,20 Other strategies to reduce parasitic absorption without adopting the complex IBC design have focused on thinning the a-Si:H films, 81 diluting them with carbon and oxygen, [82][83][84] replacing the doped a-Si:H with nano-crystalline silicon and silicon oxide, 76,85,86 and investigating alternatives to ITO. 87 Indeed, numerical device modelling indicates that widening the bandgap of the deposited layers in the SHJ contact configuration can also have beneficial impacts on Voc and FF.…”

Section: Mis Passivating Contactsmentioning

confidence: 99%

Passivating contacts for crystalline silicon solar cells

et al. 2019

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The global photovoltaic (PV) market is dominated by crystalline silicon (c-Si) based technologies with heavily doped, directly metallised contacts. Recombination of photogenerated electrons and holes at the contact regions is increasingly constraining the power conversion efficiencies of these devices as other performance-limiting energy losses are overcome. To move forward, c-Si PV technologies must implement alternative contacting approaches. Passivating contacts, which incorporate thin films within the contact structure that simultaneously supress recombination and promote charge carrier selectivity, are a promising next step for the mainstream c-Si PV industry. In this work we review the fundamental physical processes governing contact formation in c-Si. In doing so we identify the role passivating contacts play in increasing c-Si solar cell efficiencies beyond the limitations imposed by heavy doping and direct metallisation. Strategies towards the implementation of passivating contacts in industrial environments are discussed.

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Characterization of Ultra-thin μc-Si:H Films for Silicon Heterojunction Solar Cells

Cited by 14 publications

References 22 publications

Substrate‐independent analysis of microcrystalline silicon thin films using UV Raman spectroscopy

Substrate‐independent analysis of microcrystalline silicon thin films using UV Raman spectroscopy

Strategies for Doped Nanocrystalline Silicon Integration in Silicon Heterojunction Solar Cells

Passivating contacts for crystalline silicon solar cells

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