Please use this identifier to cite or link to this item: http://hdl.handle.net/1942/36174
Title: Mechanisms of charge carrier transport in polycrystalline silicon passivating contacts
Authors: Galleni, L.
FIRAT, Meric 
Radhakrishnan, H. Sivaramakrishnan
DUERINCKX, Filip 
TOUS, Loic 
POORTMANS, Jef 
Issue Date: 2021
Publisher: ELSEVIER
Source: Solar energy materials and solar cells, 232 , (Art N° 111359)
Abstract: We use temperature-dependent contact resistivity (rho c) measurements to systematically assess the dominant electron transport mechanism in a large set of poly-Si passivating contacts, fabricated by varying (i) the annealing temperature (Tann), (ii) the oxide thickness (tox), (iii) the oxidation method, and (iv) the surface morphology of the Si substrate. The results show that for silicon oxide thicknesses of 1.3-1.5 nm, the dominant transport mechanism changes from tunneling to drift-diffusion via pinholes in the SiOx layer for increasing Tann. This transition occurs for Tann in the range of 850 degrees C-950 degrees C for a 1.5 nm thick thermal oxide, and 700 degrees C-750 degrees C for a 1.3 nm thick wet-chemical oxide, which suggests that pinholes appear in wet-chemical oxides after exposure to lower thermal budgets compared to thermal oxides. For SiOx with tox = 2 nm, grown either thermally or by plasma-enhanced atomic layer deposition, carrier transport is pinhole-dominant for Tann = 1050 degrees C, whereas no electric current through the SiOx layer could be detected for lower Tann. Remarkably, the dominant transport mechanism is not affected by the substrate surface morphology, although lower values of rho c were measured on textured wafers compared to planar surfaces. Lifetime measurements suggest that the best carrier selectivity can be achieved by choosing Tann right above the transition range, but not too high, in order to induce pinhole dominant transport while preserving a good passivation quality.
Notes: Galleni, L (corresponding author), IMEC, Kapeldreef 75, B-3001 Leuven, Belgium.
laura.galleni@imec.be
Keywords: Poly-Si; Passivating contacts; Tunneling transport; Pinhole transport;;Contact resistivity; Transfer length method
Document URI: http://hdl.handle.net/1942/36174
ISSN: 0927-0248
e-ISSN: 1879-3398
DOI: 10.1016/j.solmat.2021.111359
ISI #: WOS:000694783700005
Rights: © 2021 Elsevier B.V. All rights reserved.
Category: A1
Type: Journal Contribution
Validations: ecoom 2022
Appears in Collections:Research publications

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