Ion implantation for poly-Si passivated back-junction back-contacted solar cells

verfasst von

Udo Römer, Robby Peibst, Tobias Ohrdes, Bianca Lim, Jan Krügener, Tobias Wietler, Rolf Brendel

Abstract

We study ion implantation for patterned doping of back-junction back-contacted solar cells with polycrystalline-monocrystalline Si junctions. In particular, we investigate the concept of counterdoping, that is, a process of first implanting a blanket emitter and afterward locally overcompensating the emitter by applying masked ion implantation for the back surface field (BSF) species. On planar test structures with blanket implants, we measure saturation current densities J_0,poly of down to 1.0 ± 1.1 fA/cm² for wafers passivated with phosphorus-implanted poly-Si layers and 4.4 ± 1.1 fA/cm² for wafers passivated with boron-implanted poly-Si layers. The corresponding implied pseudofill factors pFF_impl. are 87.3% and 84.6%, respectively. Test structures fabricated with the counterdoping process applied on a full area also exhibit excellent recombination behavior (J_0,poly = 0.9 ± 1.1 fA/cm², pFF_impl. = 84.7%). By contrast, the samples with patterned counterdoped regions exhibit a far worse recombination behavior dominated by a recombination mechanism with an ideality factor n > 1. A comparison with the blanket-implanted test structures points to recombination in the space charge region inside the highly defective poly-Si layer. Consequently, we suggest introducing an undoped region between emitter and BSF in order to avoid the formation of p⁺/n⁺ junctions in poly-Si.

Organisationseinheit(en)

Institut für Materialien und Bauelemente der Elektronik
Institut für Festkörperphysik

Externe Organisation(en)

Institut für Solarenergieforschung GmbH (ISFH)

Typ

Artikel

Journal

IEEE journal of photovoltaics

Band

5

Seiten

507-514

Anzahl der Seiten

8

ISSN

2156-3381

Publikationsdatum

01.03.2015

Publikationsstatus

Veröffentlicht

Peer-reviewed

Ja

ASJC Scopus Sachgebiete

Elektronische, optische und magnetische Materialien, Physik der kondensierten Materie, Elektrotechnik und Elektronik

Ziele für nachhaltige Entwicklung

SDG 7 – Erschwingliche und saubere Energie

Elektronische Version(en)

https://doi.org/10.1109/jphotov.2014.2382975 (Zugang: Geschlossen)