Temperature-dependent contact resistance of carrier selective Poly-Si on oxide junctions

Folchert, Nils; Rienäcker, Michael; Yeo, A.A.; Min, Byungsul; Peibst, Robby; Brendel, Rolf

doi:10.1016/j.solmat.2018.05.046

Cited by 57 publications

(68 citation statements)

References 22 publications

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“…The two main hypotheses are transport by tunnel effect or direct transport through nanometric pinholes forming within the SiO x layer upon annealing . As there are many ways to form the poly‐Si/SiO x structure, the answer might be process‐dependent . The pinhole formation within the SiO x layer has been revealed by means of a selective chemical etching coupled with microscopic observations .…”

Section: Resultsmentioning

confidence: 99%

“…[12] As there are many ways to form the poly-Si/SiO x structure, the answer might be process-dependent. [15] The pinhole formation within the SiO x layer has been revealed by means of a selective chemical etching coupled with microscopic observations. [13] C-AFM has also been identified as an interesting technique to investigate the existence of pinholes within the SiO x layer.…”

Section: Transport Mechanism Of Charge Carriers Through Sio X Layermentioning

confidence: 99%

“…However, it has been shown that the SiO x integrity is altered upon annealing leading to the hypothesis of a direct transport through pinholes within the SiO x layer . Recent studies focus on the detection of pinholes through SiO x layer, notably by means of conductive Atomic Force Microscopy (C‐AFM) …”

Section: Introductionmentioning

confidence: 99%

“…However, it has been shown that the SiO x integrity is altered upon annealing [10,11] leading to the hypothesis of a direct transport through pinholes within the SiO x layer. [12] Recent studies focus on the detection of pinholes through SiO x layer, [13][14][15] notably by means of conductive Atomic Force Microscopy (C-AFM). [16][17][18] In the present study, a hole-selective poly-Si contact was developed by depositing a boron-doped a-Si:H (a-Si[B]) layer by PECVD on top of a thin SiO x layer, followed by an annealing step to obtain the final poly-Si(B)/SiO x structure.…”

Section: Introductionmentioning

confidence: 99%

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Conductivity and Surface Passivation Properties of Boron‐Doped Poly‐Silicon Passivated Contacts for c‐Si Solar Cells

Morisset

Cabal

Grange

et al. 2018

Physica Status Solidi (a)

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Passivating the contacts of crystalline silicon (c‐Si) solar cells with a poly‐crystalline silicon (poly Si) layer on top of a thin silicon oxide (SiOx) film are currently of growing interest to reduce recombination at the interface between the metal electrode and the c‐Si substrate. This study focuses on the development of boron‐doped poly‐Si/SiOx structure to obtain a hole selective passivated contact with a reduced recombination current density and a high photo‐voltage potential. The poly‐Si layer is obtained by depositing a hydrogen‐rich amorphous silicon layer by plasma enhanced chemical vapor deposition (PECVD) exposed then to an annealing step. Using the PECVD route enables to single side deposit the poly Si layer, however, a blistering of the layer appears due to its high hydrogen content, which leads to the degradation of the poly‐Si layer after annealing. In this study, the deposition temperature and gas flow ratio used during PECVD step are optimized to obtain blister‐free poly‐Si layer. The stability of the surface passivation properties over time is shown to depend on the blister density. The surface passivation properties are further improved thanks to a post process hydrogenation step. As a result, a mean implied photo‐voltage value of 714 mV is obtained.

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Section: Resultsmentioning

confidence: 99%

Section: Transport Mechanism Of Charge Carriers Through Sio X Layermentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Conductivity and Surface Passivation Properties of Boron‐Doped Poly‐Silicon Passivated Contacts for c‐Si Solar Cells

Morisset

Cabal

Grange

et al. 2018

Physica Status Solidi (a)

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“…Such a methodology has been successfully applied to advanced semiconductor devices design and processes [34]- [40], [44]- [46], from which material properties like tunneling masses and thermionic emission parameters are also taken [34]. In this paper, we do not perform an extensive experimental characterization to assess the applicability of contradicting transport mechanisms (tunneling or pinholes) for solar cell devices processes [47], [48]. Accordingly, the presented results and conclusions should be interpreted taking this in account.…”

Section: Introductionmentioning

confidence: 99%

Numerical Simulations of IBC Solar Cells Based on Poly-Si Carrier-Selective Passivating Contacts

Procel

Yang

Isabella

et al. 2019

IEEE J. Photovoltaics

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This paper presents an analysis of physical mechanisms related to operation and optimization of interdigitated back contact (IBC) poly-silicon-based devices. Concepts of carrier selectivity and tunneling are used to identify the parameters that impact on the fill factor. Then, based on technology computer-aided design (TCAD) numerical simulations, we describe the device performance in terms of transport and passivation. A validation of the model is performed by matching measured and simulated R, T, and external quantum efficiency spectra and electrical parameters. As result of such process, the opto-electrical losses of the reference device are identified. Then, we execute a study of the impact of process parameters on the performance of the IBC device under analysis. Assuming a uniform SiO 2 layer, simulation results reveal that both n-type and p-type poly-Si contacts can be theoretically perfect (i.e., approx. lossless), if assuming no interface recombination but considering tunneling of both carrier types. In other words, there exists an optimum oxide thickness (1 nm) for which majority carriers tunneling works already very well, and minority tunneling is still low enough to not result in significant recombination. Moreover, SiO 2 thickness up to maximum 1.6 nm is crucial to achieve high efficiency. Regarding rear geometry analysis, the efficiency curve as a function of emitter width peaks at 70% of pitch coverage. Further, it is shown that diffused dopants inside crystalline silicon make the device resilient to passivation quality. Finally, the calibrated model is used to perform an optimization study aiming at calculating the performance limit. The estimated performance limit is 27.3% for a 100-μm-thick bulk, 20-nm-thick poly-silicon layers, silver as rear contact, and double ARC. where he worked on advanced opto-electrical simulations of interdigitated back contacted solar cells. Since 2017, he has been with the Delft University of Technology as a Postdoctoral Researcher focusing on design and development of silicon heterojunction solar cells. His research interests include opto-electrical simulations and design of solar cells and semiconductor devices.Guangtao Yang received the Ph.D. degree from the Delft University of Technology, Delft, The Netherlands, in 2015, for his research on high-efficiency n-i-p thin-film silicon solar cells.Between 2015 and 2017, he was a Postdoctoral Researcher with the Delft University of Technology, focusing on poly-Si carrier-selective passivating contacts and their application in high-efficiency interdigital back-contacted c-Si solar cells. From January 2018 to June 2018, he was a Postdoctoral Researcher with the Eindhoven University of Technology. Since July 2018, he has been with the Delft University of Technology, working on carrier-selective passivating contacts based on poly-Si and its alloys, and transition metal-oxides.Olindo Isabella received the Ph.D. degree (cum laude) from the

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Impurity Gettering in Polycrystalline‐Silicon Based Passivating Contacts—The Role of Oxide Stoichiometry and Pinholes

Yang

Krügener

Feldmann

et al. 2022

Advanced Energy Materials

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Polycrystalline‐silicon/oxide (poly‐Si/SiOx) passivating contacts for high efficiency solar cells exhibit excellent surface passivation, carrier selectivity, and impurity gettering effects. However, the ultrathin SiOx interlayer can act as a diffusion barrier for metal impurities and this potentially slows down the overall gettering rate of the poly‐Si/SiOx structures. Herein, the factors that determine the blocking effects of the SiOx interlayers are identified and investigated by examining two general types of the SiOx interlayers: 1.3 nm ultrathin tunneling SiOx with negligible pinholes and 2.5 nm SiOx with thermally created pinholes. Iron is used as tracer impurity in silicon to quantify the gettering rate. By fitting the experimental gettering kinetics by a diffusion‐limited segregation gettering model, the blocking effects of the SiOx interlayers are quantified by a transport parameter. Both the oxide stoichiometry and pinhole density affect the effective transport of iron through SiOx interlayers. The oxide stoichiometry depends strongly on the oxidation method, while the pinhole density is affected by the activation temperature, doping concentration, doping technique, and possibly the dopant type as well. To enable a fast gettering process during typical high‐temperature formation of the poly‐Si/SiOx structures, a SiOx interlayer that is less stoichiometric or with a higher pinhole density is preferred.

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Temperature-dependent contact resistance of carrier selective Poly-Si on oxide junctions

Cited by 57 publications

References 22 publications

Conductivity and Surface Passivation Properties of Boron‐Doped Poly‐Silicon Passivated Contacts for c‐Si Solar Cells

Conductivity and Surface Passivation Properties of Boron‐Doped Poly‐Silicon Passivated Contacts for c‐Si Solar Cells

Numerical Simulations of IBC Solar Cells Based on Poly-Si Carrier-Selective Passivating Contacts

Impurity Gettering in Polycrystalline‐Silicon Based Passivating Contacts—The Role of Oxide Stoichiometry and Pinholes

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