Passivation property of ultrathin SiOx:H / a-Si:H stack layers for solar cell applications

Lozac’h, Mickaël; Nunomura, Shota; Sai, Hitoshi; Matsubara, Koji

doi:10.1016/j.solmat.2018.05.004

Cited by 39 publications

(31 citation statements)

References 42 publications

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“…We then verified the presence of hydrogen in the poly‐Si films using FTIR measurements, as shown in Figure D. Compared to the as‐diffused sample, after the SiN x :H + FGA hydrogenation, the sample with pre‐FGA only showed a clear monohydride Si—H 1 peak, whereas the sample with pre‐AlO x :H + FGA displayed both monohydride Si—H 1 and dihydride Si—H 2 peaks, consistent with the literature . The presence of a dihydride Si—H 2 mode indicates that more hydrogen was injected into the films and incorporated with a larger amount of a‐Si phase .…”

supporting

confidence: 83%

“…Previously, we have noticed that in the case of low‐resistivity substrates (1 Ω cm), FGA of poly‐Si/SiO x passivating contacts resulted in little performance improvement, whereas others have reported a noticeable improvement . However, when capping layers and postdeposition annealing treatments are used, the passivating‐contact performance improves significantly, as reported by many groups . It has been shown that, without postdeposition annealing, there is no passivation improvement, and also that either annealing in N 2 or FGA shows the same performance …”

mentioning

confidence: 80%

“…We continue to assess the Si—H stretching mode at ≈2100 cm −1 from FTIR spectra captured from the sample (Figure B). The three spectra (as diffused, after FGA, and after AlO x :H + FGA) are identical and there is no signal from the Si—H bonds.…”

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confidence: 99%

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Hydrogenation Mechanisms of Poly‐Si/SiO_x Passivating Contacts by Different Capping Layers

et al. 2019

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Herein, posttreatment techniques of phosphorus‐doped poly‐Si/SiOx passivating contacts, including forming gas annealing (FGA), atomic layer deposition (ALD) of hydrogenated aluminum oxide (AlOx:H), and plasma‐enhanced chemical vapor deposition (PECVD) of hydrogenated silicon nitride (SiNx:H), are investigated and compared in terms of their application to silicon solar cells. A simple FGA posttreatment produces a significant increase in the implied open circuit voltage (iVoc) and the effective minority‐carrier lifetime (τeff) of high‐resistivity crystalline Si (c‐Si) samples, whereas low‐resistivity samples show a minimal change. Treatment by means of AlOx:H and/or SiNx:H followed by postdeposition FGA results in a universal increase in τeff and iVoc for all substrate resistivities (as high as 12.5 ms and 728 mV for 100 Ω cm and 5.4 ms and 727 mV for 2 Ω cm n‐type c‐Si substrates). In addition, both the FGA and AlOx:H + FGA techniques can inject sufficient hydrogen into the samples to passivate defects at the SiOx/c‐Si and poly‐Si/SiOx interfaces. However, this hydrogen concentration is insufficient to neutralize both the nonradiative defects inside the poly‐Si films and dangling bonds associated with the amorphous Si phase present in them. The hydrogen injected by the SiNx:H + FGA technique can passivate both the interfaces and the defects and dangling bonds within the poly‐Si film. These results are confirmed by low‐temperature photoluminescence spectroscopy, Fourier transform infrared spectroscopy, and dynamic secondary‐ion mass spectrometry measurements.

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confidence: 83%

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confidence: 80%

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Hydrogenation Mechanisms of Poly‐Si/SiO_x Passivating Contacts by Different Capping Layers

et al. 2019

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“…The band gap of the P-layer was wider than that of the I-layer to suppress light absorption loss in the P-layer, namely, the window layer of PIN solar cells. Therefore, HeNe laser light of 632 nm was hardly absorbed in the P-layer, leading to no Raman peak, while the P-layer had a large number of Si-H 2 bonds [30,31]. HeNe laser light was efficiently absorbed in the I-layer, leading to a clear Raman peak.…”

Section: Methodsmentioning

confidence: 99%

Identification and Suppression of Si-H<sub>2 </sub>Bond Formation at P/I Interface in a-Si:H Films Deposited by SiH<sub>4 </sub>Plasma CVD

Tanaka

Hara

Nagaishi

et al. 2019

Plasma and Fusion Research

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Light-induced degradation is an important problem concerning hydrogenated amorphous silicon (a-Si:H) solar cells. A-Si:H films of lower Si-H 2 bond density exhibit less light-induced degradation. In this study, Raman spectroscopy measurements of a-Si:H films with P-layer/I-layer structure reveal that high-density Si-H 2 bonds exist in the I-layer within 60 nm of the P/I interface. These Si-H 2 bonds originate from surface reactions of SiH 3 radicals, as the alternative origin (i.e., cluster incorporation) is considerably suppressed by a multi-hollow discharge plasma chemical vapor deposition method. For an I-layer thickness of 20 nm, the density ratio of Si-H 2 and Si-H bonds in the I-layer decreases from 0.133 to 0.053 as the substrate temperature increases from 170 • C to 250 • C. Fine tuning of the substrate temperature during the initial stage of I-layer deposition is thus effective in suppressing Si-H 2 bond formation at the P/I interface.

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“…Comprehensive consideration is needed when working with silicon heterojunction (SHJ) solar cells due to the fact of their low-temperature fabrication process and capability of gaining higher power conversion efficiency (PEC). The SHJ solar cells at p-type/Si (n-as well as p-layer) and n-type/Si (nplus p-layer) interfaces, with intrinsic thin amorphous silicon layers (i-layer), have invoked substantial interest due to the fact of their excellent thermal budget compared to conventional solar cells as well as having the highest PCE [1][2][3][4][5][6][7][8]. Over the last twenty years, cutting edge research on SHJ solar cells has developed several advantages: (a) a short and cost-efficient production procedure; (b) inferior degradation and ameliorate stability; (c) inferior processing temperature; and (d) high open-circuit voltage (V oc ) [5,9].…”

Section: Introductionmentioning

confidence: 99%

Simulation of Silicon Heterojunction Solar Cells for High Efficiency with Lithium Fluoride Electron Carrier Selective Layer

et al. 2020

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In this work, to ameliorate the quantum efficiency (QE), we made a valuable development by using wide band gap material, such as lithium fluoride (LiFx), as an emitter that also helped us to achieve outstanding efficiency with silicon heterojunction (SHJ) solar cells. Lithium fluoride holds a capacity to achieve significant power conversion efficiency because of its dramatic improvement in electron extraction and injection, which was investigated using the AFORS-HET simulation. We used AFORS-HET to assess the restriction of numerous parameters which also provided an appropriate way to determine the role of diverse parameters in silicon solar cells. We manifested and preferred lithium fluoride as an interfacial layer to diminish the series resistance as well as shunt leakage and it was also beneficial for the optical properties of a cell. Due to the wide band gap and better surface passivation, the LiFx encouraged us to utilize it as the interfacial as well as the emitter layer. In addition, we used the built-in electric and band offset to explore the consequence of work function in the LiFx as a carrier selective contact layer. We were able to achieve a maximum power conversion efficiency (PEC) of 23.74%, fill factor (FF) of 82.12%, Jsc of 38.73 mA cm−2, and Voc of 741 mV by optimizing the work function and thickness of LiFx layer.

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Passivation property of ultrathin SiOx:H / a-Si:H stack layers for solar cell applications

Cited by 39 publications

References 42 publications

Hydrogenation Mechanisms of Poly‐Si/SiO_x Passivating Contacts by Different Capping Layers

Hydrogenation Mechanisms of Poly‐Si/SiO_x Passivating Contacts by Different Capping Layers

Identification and Suppression of Si-H<sub>2 </sub>Bond Formation at P/I Interface in a-Si:H Films Deposited by SiH<sub>4 </sub>Plasma CVD

Simulation of Silicon Heterojunction Solar Cells for High Efficiency with Lithium Fluoride Electron Carrier Selective Layer

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Passivation property of ultrathin SiOx:H / a-Si:H stack layers for solar cell applications

Cited by 39 publications

References 42 publications

Hydrogenation Mechanisms of Poly‐Si/SiOx Passivating Contacts by Different Capping Layers

Hydrogenation Mechanisms of Poly‐Si/SiOx Passivating Contacts by Different Capping Layers

Identification and Suppression of Si-H<sub>2 </sub>Bond Formation at P/I Interface in a-Si:H Films Deposited by SiH<sub>4 </sub>Plasma CVD

Simulation of Silicon Heterojunction Solar Cells for High Efficiency with Lithium Fluoride Electron Carrier Selective Layer

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Hydrogenation Mechanisms of Poly‐Si/SiO_x Passivating Contacts by Different Capping Layers

Hydrogenation Mechanisms of Poly‐Si/SiO_x Passivating Contacts by Different Capping Layers