Thermal activation and deactivation of grown-in defects limiting the lifetime of float-zone silicon

Nicholas E. Grant*, Vladimir P. Markevich, Jack Mullins, Anthony R. Peaker, Fiacre Rougieux, Daniel Macdonald

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    85 Citations (Scopus)

    Abstract

    By studying the minority carrier lifetime in recently manufactured commercially available n- and p-type float-zone (FZ) silicon from five leading suppliers, we observe a very large reduction in the bulk lifetime when FZ silicon is heat-treated in the range 450–700 °C. Photoluminescence imaging of these samples at the wafer scale revealed concentric circular patterns, with higher recombination occurring in the centre, and far less around the periphery. Deep level transient spectroscopy measurements indicate the presence of recombination active defects, including a dominant center with an energy level at ∼Ev + 0.5 eV. Upon annealing FZ silicon at temperatures >1000 °C in oxygen, the lifetime is completely recovered, whereby the defects vanish and do not reappear upon subsequent annealing at 500 °C. We conclude that the heat-treatments at >1000 °C result in total annihilation of the recombination active defects. Without such high temperature treatments, the minority carrier lifetime in FZ silicon is unstable and will affect the development of high efficiency (>24%) solar cells and surface passivation studies.

    Original languageEnglish
    Pages (from-to)443-447
    Number of pages5
    JournalPhysica Status Solidi - Rapid Research Letters
    Volume10
    Issue number6
    DOIs
    Publication statusPublished - 1 Jun 2016

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