Passivation of aluminium-n+ silicon contacts for solar cells by ultrathin Al2O3 and SiO2 dielectric layers

James Bullock*, Di Yan, Andrés Cuevas

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    40 Citations (Scopus)

    Abstract

    Ultra-thin thermally grown SiO2 and atomic-layer-deposited (ALD) Al2O3 films are trialled as passivating dielectrics for metal-insulator-semiconductor (MIS) type contacts on top of phosphorus diffused regions applicable to high efficiency silicon solar cells. An investigation of the optimum insulator thickness in terms of contact recombination factor J0_cont and contact resistivity ρc is undertaken on 85 Ω/□ and 103 Ω/□ diffusions. An optimum ALD Al2O3 thickness of ∼22 Å produces a J0_cont of ∼300 fAcm-2 whilst maintaining a ρc lower than 1 mΩ cm2 for the 103 Ω/□ diffusion. This has the potential to improve the open-circuit voltage by a maximum 15 mV. The thermally grown SiO2 fails to achieve equivalently low J0_cont values but exhibits greater thermal stability, resulting in slight improvements in ρc when annealed for 10 minutes at 300 °C without significant changes in J0_cont. The after-anneal J0_cont reaches ∼600 fAcm-2 with a ρc of ∼2.5 mΩ cm2 for the 85 Ω/□ diffusion amounting to a maximum gain in open-circuit voltage of 6 mV.

    Original languageEnglish
    Pages (from-to)946-949
    Number of pages4
    JournalPhysica Status Solidi - Rapid Research Letters
    Volume7
    Issue number11
    DOIs
    Publication statusPublished - Nov 2013

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