Aluminum–silicon interdiffusion in silicon heterojunction solar cells with a-Si:H(i)/a-Si:H(n/p)/Al rear contacts

Jonathan L. Bryan, Joe V. Carpenter, Zhengshan J. Yu, Ashling Leilaeioun, Jianwei Shi, William Weigand, Kathryn C. Fisher, Zachary C. Holman

Research output: Contribution to journalArticlepeer-review

Abstract

We characterize a-Si:H(i)/a-Si:H(n)/Al and a-Si:H(i)/a-Si:H(p)/Al contacts implemented on the rear side of silicon heterojunction solar cells. Electrical test structures and full-area solar cells employing these contacts demonstrate promising performance. For example, a-Si:H(i)/a-Si:H(p)/Al test structures with a 40 nm thick a-Si:H(p) layer that were annealed at 180 C had contact resistivities of 48 mΩ·cm2 and implied open-circuit voltage losses after metallization of only 9 mV. Similarly, solar cells with full-area rear a-Si:H(i)/a-Si:H(n)/Al contacts that were annealed at 150 C had open-circuit voltages of 717 mV and contact resistivities of 9.4 mΩ·cm2. For thinner doped a-Si:H layers and higher annealing temperatures, the contacts become less stable and performance degrades. Complementary transmission electron microscopy and energy-dispersive x-ray spectroscopy analysis show the Al–Si interactions at these interfaces that explain the range of exhibited performance. This analysis leads to a better understanding of the materials properties limiting the contact stability.

Original languageEnglish (US)
Article number134002
JournalJournal of Physics D: Applied Physics
Volume54
Issue number13
DOIs
StatePublished - Apr 1 2021

Keywords

  • Amorphous silicon
  • Crystalline silicon
  • Photovoltaic metallization
  • Silicon heterojunction solar cells

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Acoustics and Ultrasonics
  • Surfaces, Coatings and Films

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