Study of screen printed metallization for polysilicon based passivating contacts


Ciftpinar H. E., Stodolny M. K., Wu Y., Janssen G. J. M., Loffler J., Schmitz J., ...More

7th International Conference on Crystalline Silicon Photovoltaics (SiliconPV), Freiburg, Germany, 3 - 05 April 2017, vol.124, pp.851-861 identifier identifier

  • Publication Type: Conference Paper / Full Text
  • Volume: 124
  • Doi Number: 10.1016/j.egypro.2017.09.242
  • City: Freiburg
  • Country: Germany
  • Page Numbers: pp.851-861
  • Keywords: polysilicon, polySi, passivating contact, carrier selective contact, fire through metallization, contact recombination, contact resistance, SOLAR-CELLS
  • Middle East Technical University Affiliated: Yes

Abstract

We investigate contacting of n- and p-type polysilicon (polySi) passivating contact layers with industrial screen-printed metal pastes, examining both fire through (FT) and non-fire through (NFT) pastes. The n- and p-type polySi layers, deposited by low pressure chemical vapour deposition and doped by POCl3 diffusion, phosphorus implant, or BBr3 diffusion, result in excellent J(o), even for 50 nm thickness (<2 fA/cm(2) for n-polySi, <10 fA/cm(2) for p-polySi). The contact recombination is investigated by photoluminescence, and by cell test structures to determine V-oc as a function of metallization fraction. The contact resistance is investigated by transfer length method (TLM). The contacts are also extensively studied by high resolution electron microscopy. All-polySi solar cells (i.e., cells with front and back carrier selective layers consisting of polySi) are prepared. Excellent implied V-oc, values of nearly 730 mV and 710 mV are obtained on the un-metallized polished and textured cells, respectively. The contact recombination after applying screen printed metallization can be analyzed well with both methods (PL and V-oc-based) rendering values for the prefactor of the recombination current J(o,c) at the contact areas of about 400 and 350 fA/cm(2) for 200 nm thick n-polySi and p-polySi, respectively. (C) 2017 The Authors. Published by Elsevier Ltd.