1,720,971 research outputs found
Low Work Function Ytterbium Silicide Contact for Doping-Free Silicon Solar Cells
No full textsponsorship: The authors thank Pieter Lagrain, Olivier Richard, and Hugo Bender for TEM measurement. Moreover, the authors gratefully acknowledge the financial support of imec's industrial affiliation program for Si-PV. The work in this paper was partially funded by the Kuwait Foundation for the Advancement of Sciences under project number CN18-15EE01. imec is a partner in EnergyVille (www.energyville.be), a collaboration between the Flemish research partners KU Leuven, VITO, imec, and UHasselt in the field of sustainable energy and intelligent energy systems. (Kuwait Foundation for the Advancement of Sciences|CN18-15EE01, imec's industrial affiliation program for Si-PV)status: Publishe
Evidence of TiOx reduction at the SiOx/TiOx interface of passivating electron-selective contacts
No full textA TiOx layer is well known as an electron-selective contact material because of its asymmetric band offsets with respect to c-Si. When applying TiOx layers as passivating electron-selective contacts, forming sub-stoichiometric TiOx is important to obtain a low contact resistivity because oxygen vacancies increase the conductivity of TiOx and provide n-type doping effects. In this work, oxygen vacancies at SiOx/TiOx interfaces are investigated by atomic depth profiling of XPS measurements. Three kinds of TiOx layers are studied grown by either e-beam evaporation, atomic layer deposition or sputtering on c-Si. In all three TiOx samples, a resulting stack of c-Si/SiOx/TiOx could be noticed XPS measurements that show SiOx peaks near the c-Si/TiOx interface. Moreover, clear TiO2 peaks, which can be measured at the surface of all three TiOx layer types, gradually change to Ti or TiSi2 peaks near the SiOx/TiOx interface. This indicates that many oxygen vacancies seem to exist at the SiOx/TiOx interface. This TiOx reduction may contribute to the formation of a dipole and increased downward band bending resulting in a lower contact resistivity in the electron-selective contacts. As a result, hetero-junction solar cells with i-a-Si: H/TiOx/Ca/Al contacts exhibit a significant series resistance reduction of about 40% compared to solar cells with i-a-Si: H/Ca/Al contacts.imec's industrial affiliation program for Si-P
Optical and electrical performance of rear side epitaxial emitters for bifacial silicon solar cell application
No full text© 2019 Elsevier B.V. In this work we investigated the optical and electrical performance of p-type epitaxial layers as the rear emitter of bifacial n-type PERT solar cells. In the first part of this paper, the surface morphology of epitaxial layers grown on textured surfaces is studied. Because of the epitaxial growth, a pyramids-rounding effect is observed as a result of {311} and {911} facet propagation. The growth pattern was quantified and modelled. In the second part of this paper, the optical performance of semi-device test structures is evaluated. The trend of the optical results in bifacial solar cell structures indicates that a final pyramid angle at the rear side around 20° gives the maximum light absorption in the wafer substrate. In this work we demonstrate that the epitaxial growth of the emitter on the textured rear side of these devices can already give a pyramid angle of 25° without having to introduce any additional polishing steps to modify the morphology of the textured surface. In the last part of this paper, we present the electrical results for semi-device structures created to quantify the recombination losses in the passivated and metallized regions of those p-type epitaxial emitters. These results indicate that by introducing a rear epitaxial emitter in the bifacial n-type PERT cell structure, we can increase the implied V oc up to 17 mV compared to a diffused emitter with the same sheet resistance.sponsorship: The authors would like to thank for the financial support of imec's industrial affiliation program for Photovoltaics (IIAP-PV). In addition, this work is also supported by the Kuwait Foundation for the advancement of Sciences under project no. P115-15EE-01. The authors would also like to thank for the fruitful discussions with Ali Hajjiah, Izabela Kuzma Filipek, Patrick Choulat, Loic Tous, Hariharsudan Sivaramakrishnan Radhakrishnan and Valerie Depauw. (imec's industrial affiliation program for Photovoltaics (IIAP-PV), Kuwait Foundation for the advancement of Sciences|P115-15EE-01)status: Publishe
<i>In situ</i> phosphorus-doped polycrystalline silicon films by low pressure chemical vapor deposition for contact passivation of silicon solar cells
No full textsponsorship: The authors would like to acknowledge Rajiv Sharma from KU Leuven for his help with the interfacial oxide development, Sukhvinder Singh and Patrick Choulat from Imec for their help with the contact resistivity measurements and sample fabrication, Thomas Nuytten andStefanie Sergeant from Imec for the Raman spectroscopy measurements, Bastien Douhard and Mustafa Ayyad from Imec for SIMS measurements, Maxim Korytov, Laura Nelissen, and Patricia van Marcke from Imec for the TEM specimen preparation and measurements, and Janusz Bogda-nowicz from Imec for his help with the analysis of the Hall measurement data. This work was supported by the European Union's Horizon2020 Programme for research, technological development, and demonstra-tion [grant number 857793] ; and by the Kuwait for the Advancement of Sciences [grant number CN18-15EE-01] . (European Union's Horizon2020 Programme for research, technological development, and demonstration|857793, Kuwait for the Advancement of Sciences|CN18-15EE-01, H2020 Societal Challenges Programme|857793)status: Publishe
Contact resistivity reduction on lowly-doped n-type Si using a low workfunction metal and a thin TiOx interfacial layer for doping-free Si solar cells
No full textEliminating a doping process could be an effective way to reduce the production cost of c-Si cells. However, in absence of highly doped Si, the formation of a high quality contact is not straightforward. The lack of field-effect passivation from a lowly doped region can lead to a high recombination current density at the contacts (J0,metal) and moreover, contact resistivity (ρC) typically increases when doping level is decreasing. In this work we focus on reducing the contact resistivity of an electron-selective contact for doping-free cells. Although the effect of low work function metals (LWMs) in combination with an i-a-Si:H layer has already been reported, the synergy effect of a LWM and a MIS (Metal-Insulator-Semiconductor) contact structure on top of the i-a-Si:H has not been reported yet. Here, we demonstrate a new ATOM (i-a-Si:H / TiOX / low workfunction metal) contact structure as an electron-selective contact using an i-a-Si:H layer, a TiOX interfacial layer and Ca (Φ = 2.9eV) without requiring an additional n+ doping process. The addition of TiOX in between the i-a-Si:H layer and the Ca decreases the ρC by about 2 orders of magnitude. Despite of increased J0,metal due to e-beam processing of TiOX, the Ca based ATOM contact increases the potential max efficiency up to 25 %. To the best of our knowledge, this is the first demonstration of an electron-selective contact comprising a low work function metal, an interfacial TiOX and an i-a-Si:H passivation layer. This type of contact could be a promising route for the optimization of doping-free cells.Marie Sklodowska-Curie Action; Epitaxial silicon foil solar cells with interdigitated back contacts 657270 — EpiSil-IB
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Industrial metallization of fired passivating contacts for n-type tunnel oxide passivated contact (n-TOPCon) solar cells
No full textsponsorship: This work was supported by the European Union's Horizon 2020 Programme for research, technological development, and demonstration [grant number 857793]; and by the Kuwait Foundation for the Advancement of Sciences [grant number CN18-15EE-01]. (European Union|857793, Kuwait Foundation for the Advancement of Sciences|CN18-15EE-01)status: Publishe
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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