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Fırat M, Wouters L, Lagrain P, Haase F, Polzin JI, Chaudhary A, Nogay G, Desrues T, Krügener J, Peibst R, Tous L, Sivaramakrishnan Radhakrishnan H, Poortmans J. Local Enhancement of Dopant Diffusion from Polycrystalline Silicon Passivating Contacts. ACS Appl Mater Interfaces 2022; 14:17975-17986. [PMID: 35380425 DOI: 10.1021/acsami.2c01801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Passivating contacts consisting of heavily doped polycrystalline silicon (poly-Si) and ultrathin interfacial silicon oxide (SiOx) films enable the fabrication of high-efficiency Si solar cells. The electrical properties and working mechanism of such poly-Si passivating contacts depend on the distribution of dopants at their interface with the underlying Si substrate of solar cells. Therefore, this distribution, particularly in the vicinity of pinholes in the SiOx film, is investigated in this work. Technology computer-aided design (TCAD) simulations were performed to study the diffusion of dopants, both phosphorus (P) and boron (B), from the poly-Si film into the Si substrate during the annealing process typically applied to poly-Si passivating contacts. The simulated 2D doping profiles indicate enhanced diffusion under pinholes, yielding deeper semicircular regions of increased doping compared to regions far removed from the pinholes. Such regions with locally enhanced doping were also experimentally demonstrated using high-resolution (5-10 nm/pixel) scanning spreading resistance microscopy (SSRM) for the first time. The SSRM measurements were performed on a variety of poly-Si passivating contacts, fabricated using different approaches by multiple research institutes, and the regions of doping enhancement were detected on samples where the presence of pinholes had been reported in the related literature. These findings can contribute to a better understanding, more accurate modeling, and optimization of poly-Si passivating contacts, which are increasingly being introduced in the mass production of Si solar cells.
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Affiliation(s)
- Meriç Fırat
- Department of Electrical Engineering, KU Leuven, Kasteelpark Arenberg 10, 3001 Leuven, Belgium
- Imec (Partner in EnergyVille), Kapeldreef 75, 3001 Leuven, Belgium
| | - Lennaert Wouters
- Imec (Partner in EnergyVille), Kapeldreef 75, 3001 Leuven, Belgium
| | - Pieter Lagrain
- Imec (Partner in EnergyVille), Kapeldreef 75, 3001 Leuven, Belgium
| | - Felix Haase
- ISFH, Am Ohrberg 1, 31860 Emmerthal, Germany
| | | | | | - Gizem Nogay
- CSEM, Rue Jacquet-Droz 1, 2002 Neuchâtel, Switzerland
| | - Thibaut Desrues
- Université Grenoble Alpes, CEA, LITEN, DTS, LPA, F-73370 Le Bourget-du-Lac, France
| | - Jan Krügener
- Leibniz University Hannover, Institute of Electronic Materials and Devices, Schneiderberg 32, 30167 Hannover, Germany
| | - Robby Peibst
- ISFH, Am Ohrberg 1, 31860 Emmerthal, Germany
- Leibniz University Hannover, Institute of Electronic Materials and Devices, Schneiderberg 32, 30167 Hannover, Germany
| | - Loic Tous
- Imec (Partner in EnergyVille), Kapeldreef 75, 3001 Leuven, Belgium
| | | | - Jef Poortmans
- Department of Electrical Engineering, KU Leuven, Kasteelpark Arenberg 10, 3001 Leuven, Belgium
- Imec (Partner in EnergyVille), Kapeldreef 75, 3001 Leuven, Belgium
- Hasselt University, Campus Diepenbeek, Agoralaan Gebouw D, 3590 Diepenbeek, Belgium
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Hývl M, Nogay G, Loper P, Haug FJ, Jeangros Q, Fejfar A, Ballif C, Ledinský M. Nanoscale Study of the Hole-Selective Passivating Contacts with High Thermal Budget Using C-AFM Tomography. ACS Appl Mater Interfaces 2021; 13:9994-10000. [PMID: 33591174 DOI: 10.1021/acsami.0c21282] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
We investigate hole-selective passivating contacts that consist of an interfacial layer of silicon oxide (SiOx) and a layer of boron-doped SiCx(p). The fabrication process of these contacts involves an annealing step at temperatures above 750 °C which crystallizes the initially amorphous layer and diffuses dopants across the interfacial oxide into the wafer to facilitate charge transport, but it can also disrupt the SiOx layer necessary for wafer-surface passivation. To investigate the transport mechanism of the charge carriers through the selective contact and its changes during the annealing process, we utilize various characterization methods, such as transmission electron microscopy, micro Raman spectroscopy, and conductive atomic force microscopy. Combining the latter with a sequential removal of material, we assemble a tomographic reconstruction of the crystallized layer that reveals the presence of preferential vertical transport channels.
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Affiliation(s)
- Matěj Hývl
- Institute of Physics, Academy of Sciences of the Czech Republic, Cukrovarnická 10, 162 00 Prague 6, Czech Republic
| | - Gizem Nogay
- Ecole Polytechnique Fédérale de Lausanne (EPFL), Institute of Microengineering (IMT), Photovoltaics and Thin-Film Electronics Laboratory (PV-Lab), Rue de la Maladière 71b, 2000 Neuchâtel, Switzerland
| | - Philipp Loper
- Ecole Polytechnique Fédérale de Lausanne (EPFL), Institute of Microengineering (IMT), Photovoltaics and Thin-Film Electronics Laboratory (PV-Lab), Rue de la Maladière 71b, 2000 Neuchâtel, Switzerland
| | - Franz-Josef Haug
- Ecole Polytechnique Fédérale de Lausanne (EPFL), Institute of Microengineering (IMT), Photovoltaics and Thin-Film Electronics Laboratory (PV-Lab), Rue de la Maladière 71b, 2000 Neuchâtel, Switzerland
| | - Quentin Jeangros
- Ecole Polytechnique Fédérale de Lausanne (EPFL), Institute of Microengineering (IMT), Photovoltaics and Thin-Film Electronics Laboratory (PV-Lab), Rue de la Maladière 71b, 2000 Neuchâtel, Switzerland
| | - Antonín Fejfar
- Institute of Physics, Academy of Sciences of the Czech Republic, Cukrovarnická 10, 162 00 Prague 6, Czech Republic
| | - Christophe Ballif
- Ecole Polytechnique Fédérale de Lausanne (EPFL), Institute of Microengineering (IMT), Photovoltaics and Thin-Film Electronics Laboratory (PV-Lab), Rue de la Maladière 71b, 2000 Neuchâtel, Switzerland
- PV-Center, Centre Suisse d'Électronique et de Microtechnique (CSEM), Rue Jaquet-Droz 1, CH-2002 Neuchâtel, Switzerland
| | - Martin Ledinský
- Institute of Physics, Academy of Sciences of the Czech Republic, Cukrovarnická 10, 162 00 Prague 6, Czech Republic
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Nogay G, Stuckelberger J, Wyss P, Jeangros Q, Allebé C, Niquille X, Debrot F, Despeisse M, Haug FJ, Löper P, Ballif C. Silicon-Rich Silicon Carbide Hole-Selective Rear Contacts for Crystalline-Silicon-Based Solar Cells. ACS Appl Mater Interfaces 2016; 8:35660-35667. [PMID: 27959489 DOI: 10.1021/acsami.6b12714] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The use of passivating contacts compatible with typical homojunction thermal processes is one of the most promising approaches to realizing high-efficiency silicon solar cells. In this work, we investigate an alternative rear-passivating contact targeting facile implementation to industrial p-type solar cells. The contact structure consists of a chemically grown thin silicon oxide layer, which is capped with a boron-doped silicon-rich silicon carbide [SiCx(p)] layer and then annealed at 800-900 °C. Transmission electron microscopy reveals that the thin chemical oxide layer disappears upon thermal annealing up to 900 °C, leading to degraded surface passivation. We interpret this in terms of a chemical reaction between carbon atoms in the SiCx(p) layer and the adjacent chemical oxide layer. To prevent this reaction, an intrinsic silicon interlayer was introduced between the chemical oxide and the SiCx(p) layer. We show that this intrinsic silicon interlayer is beneficial for surface passivation. Optimized passivation is obtained with a 10-nm-thick intrinsic silicon interlayer, yielding an emitter saturation current density of 17 fA cm-2 on p-type wafers, which translates into an implied open-circuit voltage of 708 mV. The potential of the developed contact at the rear side is further investigated by realizing a proof-of-concept hybrid solar cell, featuring a heterojunction front-side contact made of intrinsic amorphous silicon and phosphorus-doped amorphous silicon. Even though the presented cells are limited by front-side reflection and front-side parasitic absorption, the obtained cell with a Voc of 694.7 mV, a FF of 79.1%, and an efficiency of 20.44% demonstrates the potential of the p+/p-wafer full-side-passivated rear-side scheme shown here.
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Affiliation(s)
- Gizem Nogay
- Photovoltaics and Thin-Film Electronics Laboratory, Institute of Microengineering, École Polytechnique Fédérale de Lausanne (EPFL) , Rue de la Maladière 71b, 2002 Neuchâtel, Switzerland
| | - Josua Stuckelberger
- Photovoltaics and Thin-Film Electronics Laboratory, Institute of Microengineering, École Polytechnique Fédérale de Lausanne (EPFL) , Rue de la Maladière 71b, 2002 Neuchâtel, Switzerland
| | - Philippe Wyss
- Photovoltaics and Thin-Film Electronics Laboratory, Institute of Microengineering, École Polytechnique Fédérale de Lausanne (EPFL) , Rue de la Maladière 71b, 2002 Neuchâtel, Switzerland
| | - Quentin Jeangros
- Photovoltaics and Thin-Film Electronics Laboratory, Institute of Microengineering, École Polytechnique Fédérale de Lausanne (EPFL) , Rue de la Maladière 71b, 2002 Neuchâtel, Switzerland
- Department of Physics, University of Basel , Klingelbergstrasse 82, CH-4056 Basel, Switzerland
| | | | - Xavier Niquille
- Photovoltaics and Thin-Film Electronics Laboratory, Institute of Microengineering, École Polytechnique Fédérale de Lausanne (EPFL) , Rue de la Maladière 71b, 2002 Neuchâtel, Switzerland
| | - Fabien Debrot
- CSEM PV-Center , Jaquet-Droz 1. 2002 Neuchâtel, Switzerland
| | | | - Franz-Josef Haug
- Photovoltaics and Thin-Film Electronics Laboratory, Institute of Microengineering, École Polytechnique Fédérale de Lausanne (EPFL) , Rue de la Maladière 71b, 2002 Neuchâtel, Switzerland
| | - Philipp Löper
- Photovoltaics and Thin-Film Electronics Laboratory, Institute of Microengineering, École Polytechnique Fédérale de Lausanne (EPFL) , Rue de la Maladière 71b, 2002 Neuchâtel, Switzerland
| | - Christophe Ballif
- Photovoltaics and Thin-Film Electronics Laboratory, Institute of Microengineering, École Polytechnique Fédérale de Lausanne (EPFL) , Rue de la Maladière 71b, 2002 Neuchâtel, Switzerland
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Johlin E, Al-Obeidi A, Nogay G, Stuckelberger M, Buonassisi T, Grossman JC. Nanohole Structuring for Improved Performance of Hydrogenated Amorphous Silicon Photovoltaics. ACS Appl Mater Interfaces 2016; 8:15169-15176. [PMID: 27227369 DOI: 10.1021/acsami.6b00033] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
While low hole mobilities limit the current collection and efficiency of hydrogenated amorphous silicon (a-Si:H) photovoltaic devices, attempts to improve mobility of the material directly have stagnated. Herein, we explore a method of utilizing nanostructuring of a-Si:H devices to allow for improved hole collection in thick absorber layers. This is achieved by etching an array of 150 nm diameter holes into intrinsic a-Si:H and then coating the structured material with p-type a-Si:H and a conformal zinc oxide transparent conducting layer. The inclusion of these nanoholes yields relative power conversion efficiency (PCE) increases of ∼45%, from 7.2 to 10.4% PCE for small area devices. Comparisons of optical properties, time-of-flight mobility measurements, and internal quantum efficiency spectra indicate this efficiency is indeed likely occurring from an improved collection pathway provided by the nanostructuring of the devices. Finally, we estimate that through modest optimizations of the design and fabrication, PCEs of beyond 13% should be obtainable for similar devices.
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Affiliation(s)
- Eric Johlin
- Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
| | - Ahmed Al-Obeidi
- Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
| | - Gizem Nogay
- École Polytechnique Fédérale de Lausanne , CH-1015 Lausanne, Switzerland
| | | | - Tonio Buonassisi
- Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
| | - Jeffrey C Grossman
- Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
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Ilday S, Ilday FÖ, Hübner R, Prosa TJ, Martin I, Nogay G, Kabacelik I, Mics Z, Bonn M, Turchinovich D, Toffoli H, Toffoli D, Friedrich D, Schmidt B, Heinig KH, Turan R. Multiscale Self-Assembly of Silicon Quantum Dots into an Anisotropic Three-Dimensional Random Network. Nano Lett 2016; 16:1942-1948. [PMID: 26865561 DOI: 10.1021/acs.nanolett.5b05158] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Multiscale self-assembly is ubiquitous in nature but its deliberate use to synthesize multifunctional three-dimensional materials remains rare, partly due to the notoriously difficult problem of controlling topology from atomic to macroscopic scales to obtain intended material properties. Here, we propose a simple, modular, noncolloidal methodology that is based on exploiting universality in stochastic growth dynamics and driving the growth process under far-from-equilibrium conditions toward a preplanned structure. As proof of principle, we demonstrate a confined-but-connected solid structure, comprising an anisotropic random network of silicon quantum-dots that hierarchically self-assembles from the atomic to the microscopic scales. First, quantum-dots form to subsequently interconnect without inflating their diameters to form a random network, and this network then grows in a preferential direction to form undulated and branching nanowire-like structures. This specific topology simultaneously achieves two scale-dependent features, which were previously thought to be mutually exclusive: good electrical conduction on the microscale and a bandgap tunable over a range of energies on the nanoscale.
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Affiliation(s)
- Serim Ilday
- Department of Micro and Nanotechnology, Middle East Technical University , 06800, Ankara, Turkey
| | | | - René Hübner
- Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf , D-01328 Dresden, Germany
| | - Ty J Prosa
- CAMECA Instruments Inc. , Madison, Wisconsin 53711 United States
| | - Isabelle Martin
- CAMECA Instruments Inc. , Madison, Wisconsin 53711 United States
| | - Gizem Nogay
- Department of Physics, Middle East Technical University , 06800, Ankara, Turkey
| | - Ismail Kabacelik
- Department of Physics, Akdeniz University , 07058, Antalya, Turkey
| | - Zoltan Mics
- Max Planck Institute for Polymer Research , Ackermannweg 10, 55128 Mainz, Germany
| | - Mischa Bonn
- Max Planck Institute for Polymer Research , Ackermannweg 10, 55128 Mainz, Germany
| | - Dmitry Turchinovich
- Max Planck Institute for Polymer Research , Ackermannweg 10, 55128 Mainz, Germany
| | - Hande Toffoli
- Department of Physics, Middle East Technical University , 06800, Ankara, Turkey
| | - Daniele Toffoli
- Dipartimento di Scienze Chimiche e Farmaceutiche, Universita di Trieste , Via L. Giorgieri 1, 34127 Trieste, Italy
| | - David Friedrich
- Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf , D-01328 Dresden, Germany
| | - Bernd Schmidt
- Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf , D-01328 Dresden, Germany
| | - Karl-Heinz Heinig
- Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf , D-01328 Dresden, Germany
| | - Rasit Turan
- Department of Physics, Middle East Technical University , 06800, Ankara, Turkey
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