Comparative Studies of Optoelectronic Properties, Structures, and Surface Morphologies for Phosphorus-Doped Poly-Si/SiOx Passivating Contacts

Thien Truong, Di Yan, Harvey Guthrey, Mowafak Al-Jassim, Daniel Madonald, Hieu Nguyen

Research output: Contribution to conferencePaper

Abstract

We investigated and compared optoelectronic properties, crystallographic structures, and nanoscale surface morphologies of ex-situ phosphorus-doped polycrystalline silicon (poly-Si)/SiO x passivating contacts, formed by different deposition methods (sputtering, plasma-enhanced chemical vapour deposition (PECVD), and low-pressure chemical vapour deposition (LPCVD)). Across all these deposition technologies, a similar trend is observed: higher diffusion temperatures yield films that are more crystalline but have rougher surface morphologies due to bigger surface crystal grains. Also, the recrystallization process of the as-deposited Si films starts from the SiO x interface, rather than from the film surface and bulk. However, there are some distinct differences among these technologies. Firstly, the LPCVD method yields the roughest surface and smallest degree of crystallinity on finished poly-Si films. In contrast, the PECVD method has the smoothest surface for both as-deposited Si and annealed poly-Si films. Secondly, as-deposited sputtered and PECVD Si films contain only an amorphous phase whereas as-deposited LPCVD films has already had some crystalline phase. Thirdly, the LPCVD phosphorus in-diffusion into the substrate depends strongly on the initial film thickness, whereas for the other two methods it is weakly dependent on thickness.
Original languageAmerican English
Pages130-133
Number of pages4
DOIs
StatePublished - 2021
Event2021 IEEE 48th Photovoltaic Specialists Conference (PVSC) -
Duration: 20 Jun 202125 Jun 2021

Conference

Conference2021 IEEE 48th Photovoltaic Specialists Conference (PVSC)
Period20/06/2125/06/21

NREL Publication Number

  • NREL/CP-5K00-81263

Keywords

  • crystallographic structures
  • optoelectronic properties
  • passivating contacts
  • POLO
  • poly-Si
  • surface morphologies
  • TOPCon

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