Investigation of Gallium-Boron Spin-On Codoping for Poly-Si/SiOx Passivating Contacts

Thien Truong, Tien Le, Di Yan, Sieu Phang, Mike Tebyetekerwa, Matthew Young, Mowafak Al-Jassim, Andres Cuevas, Daniel Macdonald, Josua Stuckelberger, Hieu Nguyen

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4 Scopus Citations


A doping technique for p-type poly-Si/SiOx passivating contacts using a spin-on method for different mixtures of Ga and B glass solutions is presented. Effects of solution mixing ratios on the contact performance (implied open circuit voltage iVoc, contact resistivity ρc) are investigated. For all as-annealed samples at different drive-in temperatures, increasing the percentage of Ga in the solution shows a decrement in iVoc (from ∼680 to ∼610 mV) and increment in ρc (from ∼3 to ∼800 mΩ cm2). After a hydrogenation treatment by depositing a SiNx/AlOx stack followed by forming gas annealing, all samples show improved iVoc (∼700 mV with Ga-B co-doped, and ∼720 mV with all Ga). Interestingly, when co-doping Ga with B, even a small amount of B in the mixing solution shows negative effects on the surface passivation. Active and total dopant profiles obtained by electrical capacitance voltage and secondary-ion mass spectrometry measurements, respectively, reveal a relatively low percentage of electrically-active Ga and B in the poly-Si and Si layers. These results help understand the different features of the two dopants: a low ρc with B, a good passivation with Ga, their degree of activation inside the poly-Si and Si layers, and the annealing effects.

Original languageAmerican English
Article number2100653
Number of pages6
JournalSolar RRL
Issue number12
StatePublished - 2021

Bibliographical note

Publisher Copyright:
© 2021 Wiley-VCH GmbH.

NREL Publication Number

  • NREL/JA-5F00-79975


  • boron
  • gallium
  • passivating contacts
  • POLO
  • poly-Si
  • spin-on doping
  • TOPCon


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