Contact resistivity of n-type amorphous silicon electron contacts in silicon heterojunction solar cells

William Weigand, Ashling Mehdi Leilaeioun, Tien Ngo, Stefen Mercado, Zachary Holman

Research output: Chapter in Book/Report/Conference proceedingConference contribution

3 Scopus citations

Abstract

Silicon heterojunction solar cells have historically suffered from high series resistivities. Yet, until recently, little had been done to understand the main factors behind this behavior. In this work, we present a systematic analysis in order to quantify and characterize the contribution from each layer of a-Si:H(i)/aSi:H(n)/ITO/Ag electron contacts. We attempt to address how the stack performs when its constituent layers are altered, using the transfer length method. Specifically, we demonstrate how the thickness of the a-Si:H layers and the doping of the ITO layers contribute to the overall series resistivity via changes in contact resistivity. From these results, we determine the optimum process conditions to minimize the resistivity of the electron contact, and thus its contribution to fill factor losses. We find that increasing the a-Si:H(i) thickness and the oxygen partial pressure during ITO sputtering leads to an increase in contact resistivity. Specifically, by increasing the a-Si:H(i) layer thickness from 0 to 15 nm the contact resistivity increases from 0.15 to 0.35 Ωcm2 for our standard ITO layer. By increasing the oxygen partial pressure during ITO sputtering from 0.14 to 0.85 mTorr the contact resistivity increases from 0.07 to 0.82 Ωcm2 for a standard a-Si:H(i) layer thickness. On the other hand, increasing the a-Si:H(n) layer thickness has little effect on the contact resistivity, with a constant value of 0.07 Ωcm2 for thicknesses greater than 3 nm.

Original languageEnglish (US)
Title of host publication2018 IEEE 7th World Conference on Photovoltaic Energy Conversion, WCPEC 2018 - A Joint Conference of 45th IEEE PVSC, 28th PVSEC and 34th EU PVSEC
PublisherInstitute of Electrical and Electronics Engineers Inc.
Pages3905-3907
Number of pages3
ISBN (Electronic)9781538685297
DOIs
StatePublished - Nov 26 2018
Event7th IEEE World Conference on Photovoltaic Energy Conversion, WCPEC 2018 - Waikoloa Village, United States
Duration: Jun 10 2018Jun 15 2018

Other

Other7th IEEE World Conference on Photovoltaic Energy Conversion, WCPEC 2018
CountryUnited States
CityWaikoloa Village
Period6/10/186/15/18

Keywords

  • carrier-selective contacts
  • contact resistivity
  • photovoltaic cells
  • silicon

ASJC Scopus subject areas

  • Energy Engineering and Power Technology
  • Renewable Energy, Sustainability and the Environment
  • Electrical and Electronic Engineering
  • Electronic, Optical and Magnetic Materials

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    Weigand, W., Leilaeioun, A. M., Ngo, T., Mercado, S., & Holman, Z. (2018). Contact resistivity of n-type amorphous silicon electron contacts in silicon heterojunction solar cells. In 2018 IEEE 7th World Conference on Photovoltaic Energy Conversion, WCPEC 2018 - A Joint Conference of 45th IEEE PVSC, 28th PVSEC and 34th EU PVSEC (pp. 3905-3907). [8548308] Institute of Electrical and Electronics Engineers Inc.. https://doi.org/10.1109/PVSC.2018.8548308