GADEST 2017 Program and submitted abstracts

Program and submitted abstracts

Gettering and Defect Engineering In Semiconductor Technology XVII

GADEST 2017

XVIIth International Biannual Meeting, Lopota resort, Kacheti, Georgia October 01-06, 2017

Ivane Javakhishvili Tbilisi State University Faculty of Exact and Natural Sciences

Lopota Resort, Georgia

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Program and submitted abstracts

XVIIth International Biannual Meeting Gettering and Defect Engineering in Semiconductor Technology GADEST 2017

Chairpersons: Teimuraz Mchedlidze, Technische Universität Dresden, Germany Hans Richter, GFWW Frankfurt (Oder), Germany Alexander Shengelaya, Ivane Javakhishvili Tbilisi State University, Georgia

Executive Secretary: Tamar Tchelidze, Ivane Javakhishvili Tbilisi State University, Georgia

Executive Committee: Robert Falster, SunEdison Semiconductor, United Kingdom Hermann Grimmeiss, University of Lund, Sweden Martin Kittler, IHP Frankfurt (Oder) & BTU Cottbus-Senftenberg, Germany Vitaly V. Kveder, Institute of Solid State Physics, Russia Teimuraz Mchedlidze, Technische Universität Dresden, Germany John Murphy, University of Warwick, United Kingdom Peter Pichler, Fraunhofer IISB, Germany Hans Richter, GFWW Frankfurt (Oder), Germany Hele Savin, Aalto University, Finland Alexander Shengelaya, Ivane Javakhishvili Tbilisi State University, Georgia Peter Wilshaw, University of Oxford, United Kingdom

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International Program Committee: Daniel Alquier, University of Tours, France Hartmut Bracht, Universität Münster, Germany Ekaterine Chikoidze, Paris Saclay University, CNRS, France Marisa Di Sabatino Lundberg, Institutt for materialteknologi, Norway Vadim Emtsev, Ioffe Phyiscal-Technical Institute, Russia Stefan K. Estreicher, Texas Tech University, USA Marco Fanciulli, University of Milano Bicocca, Italy Manfred Horstmann, GlobalFoundries, Germany Daniel MacDonald, The Australian National University, Australia Tony Peaker, University of Manchester, United Kingdom Takashi Sekiguchi, National Institute for Materials Science, Japan Nikolay A. Sobolev, Ioffe Phyiscal-Technical Institute, Russia Koji Sueoka, Okayama Prefectural University, Japan Jörg Weber, Technische Universität Dresden, Germany Deren Yang, Zhejiang University, China Peter Zaumseil, IHP microelectronics, Germany

Local Organizing Committee, Ivane Javakhoishvili Tbilisi State University, Tbilisi, Georgia Chkhenkeli, Mikheil Shengelaya, Alexander Tchelidze, Tamar Tabidze, Mirian Kvernadze, Maguli Machavariani, Zaal Gavasheli, Tsismaru Trapaidze, Lia Makhviladze, Mikheil Mghebrishvili, Kakha Barbakadze, Shota Gamkrelidze, Ketevan Tsiskarishvili, Nino Samkharadze, Maia

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Preface The booklet contains the program and the abstracts of the 17th International Conference on Gettering and Defect Engineering in Semiconductor Technology (GADEST 2017), held at Lopota Spa and Resort, Kacheti Region, Georgia. The GADEST conference series was established in 1985 by Hans Richter of the Institute for Physics of Semiconductors of the Academy of Science of the former German Democratic Republic. From its beginning, it was intended as an international forum for experts in the field of semiconductor technology, semiconductor device physics and defect physics with participants from academia as well as from industry. Since 1985, GADEST has been organized biennially at typically remote sites to encourage interactions and discussions among the participants. From its beginning the conference was meant to be a meeting place between scientists from east and west. Georgia located at the very border between the Europe and Asia best suits for the meeting. The GADEST 2017 conference covers a broad range of topics related to the semiconductor science and technology. Topics ranging from fundamental scientific aspects to engineering solutions were included in a forum. The conference serves as a ground for fruitful interaction between scientists and engineers engaged in the fields of semiconductor defect physics, materials science and technology. Defects in materials and devices, physics and technology of devices used in nano-, microelectronics, power electronics and photovoltaics are traditionally at the heart of the conference. While silicon-based technologies are traditionally in the focus of the conference, many aspects related to other materials are also presented. We would like to thank the members of the conference committees for their suggestions and strong support during preparation of the conference. We would like to thank also the Local Organizing Committee members for all what was necessary to get the conference running. Our special thanks are due to Peter Pichler and Martin Kittler. Their help and guidance allowed us preparing the conference with confidence. Chairs of the conference: T. Mtchedlidze, H. Richter, A. Shengelaya

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Program and submitted abstracts

Program

Sunday, October 01, 2017 SuO: Opening Session Chairs:

Teimuraz Mchedidze and Alexander Shengelaya

16:00-16:10

Conference opening

16:10-16-50 Keynote 01

Current status and future prospects of photovoltaic research and technology

Green, Martin 16:50-17:20

Keynote 02

History of GADEST conferences

Richter, Hans 17:20-18:00

Invited Su.I01

Group IV alloys for electronic, photonic and thermoelectric applications

Radamson , Henry H. 18:30-

Welcome party

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Monday, October 02, 2017 Mo1 Session: PV materials engineering Chairperson:

Martin Green

9:00-9:40

Invited Mo.I01:

Impurity Control in High Performance Multicrystalline Silicon

Stokkan, Gaute 9:40-10:00

Mo.O02:

Using low temperature gettering to improve multicrystalline silicon for photovoltaics

Murphy, John 10:00-10:40

Invited Mo.I03:

Photovoltaic operation of perovskite solar cells: what we understand and don’t yet understand

Katz, Eugene A. 10:40-11:00

Coffee break

Mo2 Session: Passivation and gettering for solar silicon Chairperson:

Hele Savin

11:00-11:40

Invited Mo.I04:

New perspectives on field effect passivation of silicon surfaces

Bonilla, Ruy Sebastian 11:40-12:20

Invited Mo.I05:

The role of hydrogenation and gettering in enhancing the efficiency of next generation Si solar cells: an industrial perspective

Hallam, Brett 12:30-14:00

Lunch break

Mo3 Session: Hydrogen in Silicon Chairperson:

Joerg Weber

14:00-14:40

Invited Mo.I07:

Theory of a major recombination trap in n-type solar Si: the carbon-oxygenhydrogen complex

Coutinho, Jose 14:40-15:00

Mo.O08:

Hydrogen-related deep states in n-type silicon

Kolevatov, Ilia 15:00-15:20

Mo.O09:

Impact of grain boundaries and hydrogen on light-induced degradation in multicrystalline silicon

Lindroos, Jeanette 15:20:15:40

Mo.O10:

Shielded Hydrogen Passivation - a potential in-line passivation process

Bourret-Sicotte, Gabrielle 15:40-16:00

Coffee break

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Mo4 Session: Hydrogen related reactions Chairperson:

Tony Peaker

16:00-16:40

Invited Mo.I11:

Challenges and opportunities for the introduction of hydrogen to silicon solar cells at low temperatures

Hamer, Phillip 16:40-17:00

Mo.O12:

Modelling plasma-induced hydrogen profiles in boron-doped and nearintrinsic silicon

Falster, Robert 17:00-17:20

Mo.O13:

Carbon-hydrogen related defects in SiGe observed after dc H plasma treatment

Stübner, Ronald

18:00-19:30

Dinner

Mo5 Poster Session I 19:30-21:30

See Monday Poster Session

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Monday, October 02, 2017 No.

19:30-21:30

Presenting Author

Mo5 Poster Session I Title

Mo.P01 Savin, Hele

Unified model for iron gettering in boron- and phosphorus-implanted silicon

Mo.P02 Markevich, Vladimir P.

Radiation-induced interstitial carbon atom in silicon: Effect of charge state on annealing characteristics

Mo.P03 Ma, Xiangyang

Effect of carbon on the formation of nitrogen-oxygen complexes in Czochralski silicon

Mo.P04 Murphy, John

Super-acid passivation for measurement of extremely long bulk carrier lifetimes in silicon

Mo.P05 Sekiguchi, Takashi

Statistical considerations on the grain boundary evolution in multicrystalline Si

Mo.P06 Inglese, Alessandro

Characterization of light-activated Cu defects in silicon: comparison with the recombination activity of metallic precipitates

Mo.P07 Zharova, Yuliya

Effect of silicon doping level on morphology and plasmon resonance spectra of deposited Ag nanoparticles

Mo.P08 Tavkhelidze, Avtandil

Optical and electronic properties of periodic Si nanostructures

Mo.P09 Chakhvashvili, Lali

Using neutron transmutation for creation of impurity defects in semiconductor silicon and germanium based devices

Mo.P11 Mchedlidze, Teimuraz

Deep carrier traps in as grown isotopically pure 28Si FZ crystal

Mo.P10 Sichinava, Avtandil

Influence of radiation on mechanical properties of Si-Ge alloys

Mo.P12 Barbakadze, Karlo

Structural and thermoelectric characteristics of n- and p- types Si0,95Ge0,05 alloys compacted by hot pressing

Mo.P13 Privezentsev, Vladimir

Quartz Modification by Zn Ion Implantation and Swift Xe Ion Irradiation

Mo.P14 Mamniashvili, Grigor Ivan

Magnetometry, EPR and optical spectrometry study of the photocatalytic activity of the TiO2 micro- and nanopowders coated by cobalt nanoclusters

Mo.P15 Brehm, Moritz

Quantitative determination of radiative and non-radiative carrier recombination processes in group-IV quantum dots

Mo.P16 Daraselia, Dimitry

Nonthermal Effects in Rapid Synthesis of Perovskite Oxide Materials by Light Irradiation

Mo.P17 Beradze, Bachana

Donor impurity in quantum dots

Mo.P18 Kereselidze, Tamaz

Interband optical transitions in ellipsoidal shaped nanoparticles

Mo.P19 Sobolev, Nokolay

Influence of N-ion implantation dose on properties of GaAs

Mo.P20 Yakimov, Evgene B.

Dislocation trails in Si: Geometry and electrical properties

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Tuesday, October 03, 2017 Tu1 Session: Thermoelectrics and heat transfer Chairperson: Robert Falster 9:00-9:40

Invited Tu.I01 :

Defect engineering in silicon-based thermoelectrics

Benett, Nick 9:40-10:00

Tu.O02:

Heat flow across an oxide layer in Si

Estreicher, Stefan K. 10:00-10:40 Invited Tu.I03:

Impurity band conduction and intrinsic defects in thermoelectric material ZnSb

Song, Xin 10:40-11:00 Coffee break Tu2 Session: Si Hyperdoping, doping, growth Chairperson: Peter Pichler 11:00-11:20 Tu.O04:

Hyperdoping of silicon: A last niche of defect engineering?

Skorupa, Wolfgang 11:20-11:40 Tu.O05:

Microscopic electronic and structural analysis of femtosecond laser sulfur hyperdoped silicon

Seibt, Michael 11:40-12:00 Tu.O06:

Femtosecond Laser Texturing and Hyperdoping of Silicon for Photodetection Application

Qiu, Xiaodong 12:00:12:20 Tu.O07:

Diffusion doping of silicon with magnesium

Astrov, Yuri A 12:20:12:40

Tu.O08

New magnesium-related donor centers in silicon observed by magnetooptical absorption spectroscopy

Pavlov, Sergey 12:40-14:00 Lunch break Tu3 Session: Metals in Si and gettering Chairperson: John Murphy

14:00-14:20 Tu.O09:

Recombination via transition metals in silicon; the significance of hydrogen passivation and lattice site of the metal.

Peaker, Anthony Ralph

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14:20-14:40 Tu.O10:

Phosphorus Diffusion Gettering of Copper in Silicon

Inglese, Alessandro 14:40-15:00 Tu.O11:

Nickel in silicon: Room-temperature in-diffusion and interaction with radiation defects

Yarykin, Nikolai 15:00-15:20 Tu.O12:

Light-induced degradation in quasi-monocrystalline silicon PERC solar cells: Indications on involvement of copper

Vahlman, Henri 15:20:15:40 Tu.O13:

Saw damage gettering for industrially relevant mc-Si feed-stock

Shaw, Eleanor C 15:40-16:00 Coffee break Tu4 Session: Defect and materials engineering Chairperson: Peter Wilshaw 16:00-16:40 Invited Tu.I14:

Gettering iron with black-silicon

Savin, Hele 16:40-17:00 Tu.O15:

Two Stage Mechanism of Zn Nanoparticles Formation in ZnO Crystal by Nd:YAG Laser Radiation

Medvids, Arturs 17:00-17:40 Invited Tu.I16

Geometry-induced quantum effects in periodic nanostructures

Tavkhelidze, Avto 18:00-19:30 Dinner Tu5 Poster Session II 19:30-21:30 See Tuesday Poster Session

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Tuesday, October 03, 2017 No.

19:30-21:30

Presenting Author

Tu5 Poster Session II Title

Tu.P01 Astrova, Ekaterina

Sintering of macroporous silicon in argon

Tu.P02 Tigishvili, Marina

Impact of Damages in Monocrystalline n-Si on material Photosensitivity

Tu.P03 Khirunenko, Lyudmila Ivanovna

Electronic absorption of interstitial boron-related defects in silicon

Tu.P04 Guldamashvili, Anzor

Ion Implanted Silicon Diode for Neutron Detection

Tu.P05 Jibuti, Lado

The Athermal Melting of Superficial Layers of Semiconductors by Using of Pulse Laser Influence

Tu.P06 Sekiguchi, Takashi

Development of fountain detectors for spectroscopy of secondary electron in SEM

Tu.P07 Sekiguchi, Takashi

Secondary electron imaging of Si device structures using fountain detector

Tu.P08 Yarykin, Nikolai

Deep level centers in electron-irradiated silicon crystals with different copper doping

Tu.P09 La Mattina, Fabio

Development of a He-Ion Beam Induced Charge Scanning System

Tu.P10 Vyvenko, Oleg

Luminescent and electrical properties of oxygen implanted silicon

Tu.P11 Kurashvili, Ia

High amplitude internal friction in monocrystalline germanium-doped silicon

Tu.P12 Tabatadze, Iasha

Influence of Germanium on the thermal expansion of polycrystalline Si1-xGex(x 1018 cm-3) for the manufacturing of solar cells. All the structures show photovoltaic response to irradiation, with fill factors of approx. 30%, which is an indicator of the commercial viability of optimized layers for the manufacturing of photovoltaic composites. The results of this research will be used to select the most efficient and cost-effective materials for the fabrication of different PV systems.

Acknowledgements The authors acknowledge the financial support of the M-ERA.net No. 39/2016 project and of the grant INFRANANOCHEM (No. 19/01.03.2009) sponsored by the EU (ERDF) and Romanian Government.

Copyright line will be provided by the publisher

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Atom probe analysis of nanoscale iron and oxygen co-clustering in iron contaminated single crystal silicon subjected to Phosphorus Diffusion Gettering 1

J. O. Douglas, 1G. F. Martins, 1A. Siddique, 2J. D. Murphy, 1

1 2

P. A. J. Bagot, 1M.P. Moody

Department of Materials, University of Oxford, Parks Road, OX1 3PH, UK

School of Engineering, University of Warwick, Coventry, CV4 7AL, United Kingdom [email protected]

Iron is a major centre for carrier recombination in silicon photovoltatics and thus causes a loss of efficiency in solar cells when it is present. Phosphorus Diffusion Gettering (PDG) is a common method of removing iron contamination from the silicon bulk but the exact mechanism of the segregation of iron to the phosphorus rich surface regions is not known. One proposed mechanism from Syre et al is through the iron decoration of oxide particles formed within the phosphorus rich ‘kink’ region of the phosphorus diffusion profile [1]. Nanoscale silicon phosphide precipitates are also known to form within this phosphorus rich region and Ourmazd et al [2] proposed that the silicon interstitials emitted during their formation can induce local gettering of transition metals. Secondary Ion Mass Spectrometry (SIMS) has shown that there is a close overlap between the depth profiles of iron and oxygen within such gettered silicon samples within ~50 nm of the silicon surface [1] [3]. Due to limitations in lateral resolution in SIMS, it has not been possible to determine if these oxygen and iron species are uniformly distributed or are spatially segregated on the nanoscale. Atom Probe Tomography (APT) is an atomic scale material characterization technique for typical analysis volumes of tens of millions of atoms (80 nm x 80 nm x 250 nm) with a chemical sensitivity down to tens of ppm and a 3D spatial resolution of individual atoms down to 0.1 nm in the analysis direction. APT depth profiling has been previously shown to closely correlate with SIMS analyses of National Institute of Standards and Technology silicon reference samples [4] and is potentially an ideal complementary technique to confirm atomic scale co-clustering behavior in gettered silicon. APT analysis was carried out on iron contaminated, phosphorus diffused single crystal silicon in order to attempt to directly observe co-clustering of oxygen and iron as predicted by Syre et al [1]. As this effect is predicted to be most visible within tens of nm of the surface, extreme care must be taken in preserving and delineating the surface when fabricating the nanoscale needle sample geometry required for atom probe [5]. Therefore ex-situ capping layers of cobalt were deposited prior to optimised Focused Ion Beam based sample preparation. A finished silicon atom probe specimen with a small amount of cobalt remaining at the surface can be seen in Figure 1. Figure 1 – SEM micrograph of silicon atom probe sample with cobalt capping layer. Lopota Resort, Georgia

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Figure 2 – Left: Atom map of iron contaminated, phosphorus diffused silicon. Right: Cross-section of silicon phosphide precipitate (note gap in centre) Cobalt (blue), phosphorus (purple) and silicon (gray) atoms shown. Visual inspection of the 3D reconstruction of the atoms collected during atom probe analysis shows a high local concentration of phosphorus within tens of nm of the silicon surface (Figure 2 – Left). This high concentration of phosphorus is mainly in the form of silicon phosphide precipitates (Figure 2 – Right). Depth profiles of oxygen and phosphorus shows oxygen spatially segregating with high concentrations of phosphorus within the first ten nm (Figure 3). Isoconcentration surfaces of oxygen (10 %) and phosphorus (10 %) show that the oxygen rich region is found spatially segregated to the centre of a silicon phosphide precipitate (Figure 3 – Inset).

Figure 3 – Concentration profiles of cobalt, phosphorus, oxygen and silicon oxide. Inset: Isoconcentration surfaces of oxygen (10 %) and phosphorus (10 %) APT operates using spatially resolved time of flight mass spectrometry and so is subject to mass spectra overlap issues when analyzing species with similar mass to charge ratios. Silicon and iron have major overlaps in the form of 28Si+/56Fe2+ at 28 Da and 28Si2/56Fe+ at 56 Da and this hinders the use of these species for iron identification in low concentrations.

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The compound ion 56Fe16O2+ at 36 Da has been previously detected in iron contaminated polysilicon [6] and this species has also been shown to decorate the interface between the silicon phosphide precipitate and oxygen rich regions shown in this work (Figure 4 – Left).

Figure 4 – Left: Oxygen rich region with phosphorus (purple), oxygen (blue), silicon oxide (gray) and potential 56Fe16O2+species at 36 Da (black). All species apart from phosphorus have been enlarged for clarity. Right: Oxygen rich region with56FeO2+ (black) at 36 Da and 54FeO2+ (red) at 35 Da. The 28Si216O + species also overlaps 56Fe16O2+ at 36 Da and so can be expected to be present in reasonable quantities in the the oxygen rich region. The 54Fe16O 2+ species at 35 Da does not have this issue and this can be seen to preferentially spatially segregate to the oxygen rich region (Figure 4 – Right). Although quantification of the amount of iron to this region cannot be carried out to the numerous mass spectra overlaps, this is a reasonable indication of iron segregation to this oxygen rich region as predicted by Syre et al [1]. In this work we have shown that nanoscale oxygen segregation has been observed through APT within tens of nm of the surface of iron contaminated, phosphorus diffused silicon. These oxygen rich regions have been only found in close proximity to silicon phosphide precipitates and initial analysis indicates that iron segregation to these regions is occurring. We will present the process of optimizing FIB based sample preparation, APT analysis parameters and data processing required used to obtaining this nanoscale analysis. Oxygen segregation will be compared as a function of iron contamination and local phosphorus concentration and the implications for PDG discussed. [1] M. Syre, et al., Journal of Applied Physics, 110, 024912 (2011). [2] A. Ourmazd et al. , Materials Research Society Symposium Proceedings, 36 (1985). [3] M. B. Shabani et al., Solid State Phenomena, Vols. 131-133, pp. 399-404, (2008). [4] T. J. Prosa et al., Ultramicroscopy, 132 179-185 (2013). [5] J. O. Douglas et al., Semiconductor Science and Technology, 31, 084004, (2016). [6] B. Gorman et al., 38th IEEE Photovoltaic Specialists Conference (PVSC), (2012).

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Development of High-Performance Multi-Crystalline Silicon Crystal Growth for Solar Cells 1,2 Xinming Huang Wenliang Chen2, Genxiang Zhong1, 1

JA Solar Holdings Co., Ltd 2

Nanjing Tech University

E-mail:[email protected]

Abstract Solar cells based on high-performance (HP) multi-crystalline silicon (mc-Si) have been widely used in photovoltaic market due to well-balanced relatively high conversion efficiency and low casting cost. There are two kinds of HP mc-Si according to the different growth processes, i.e., using mc-Si particles as homo-seeds to cast seeded silicon ingots, and using fused SiO2 granules or other kinds of high melting point materials as the hetero-seeds to cast seed-assisted growth of mc-Si ingots. In the homo-seeded casting process, a flat or slightly convex seed-melt (s-m) interface and the lower height of remained seeds were required, and they can be obtained via designing the special insulated structure in the seed regions and increasing the power ratio between the top and side heaters. The quality of homo-seeded mc-Si ingots was better compared to the conventional mc-Si ingots. However, there were some problems for homo-seeded casting process in the industrial production, such as complicated growth process and relatively lower yield ratio. To solve the problems, fused SiO2 granules were used as the hetero-seeds to cast the mc-Si ingots. However, sticking of the grown silicon crystal to the seeds of silica granules occurs easily, and it was a severe problem in the production of mu-Si ingot. The Si3N4-coated SiO2granules were helpful for eliminating the stress from the bonding between the silicon crystal with the silica granules. Small and uniform initial grains were obtained, and the multiplication of dislocation clusters was significantly reduced due to the existence of the small and uniform initial grains in the seeded mc-Si ingots. On the other hand, the quality of silicon crystal is significantly affected by the thermal

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history of the growth process. A slightly convex or flat crystal-melt interface, the melt convection for pushing impurities outwards and the low thermal stress are beneficial to improve crystal quality. However, it was difficult to realize it in the conventional directional solidification (DS) casting process. The HP mc-Si with the uniform grains, vertical columnar structure and lower dislocation density was achieved under the optimized growth process designs (improved hot-zone and growth process recipes). Low oxygen concentration is beneficial to suppress the light induced degradation of p-type solar cells. The Ba-doped high-purity barrier layers were added in the inner walls of the crucible to reduce the oxygen concentration, and other contamination of the metal impurities as well. In summary, through the continuous efforts on the improvement of HP mc-Si quality, average conversion efficiency of the solar cells has been increased more than 0.5% in absolute value in comparison with that in the conventional casting mc-Si crystals under the same cell production process. The lower casting costs and the higher crystal quality are still the pursuing goals of mc-Si industry, and optimizing the seeding process and the DS process, including the melting, growth, annealing and cooling processes are still the key points for the further investigation. Key words: multi-crystalline silicon; seed-assisted; dislocation; heat transfer; solar cells

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