Exceptional gettering response of epitaxially grown kerfless silicon

D. M. Powell, V. P. Markevich, J. Hofstetter, M. A. Jensen, A. E. Morishige, S. Castellanos, B. Lai, A. R. Peaker, T. Buonassisi

    Research output: Contribution to journalArticlepeer-review

    Abstract

    The bulk minority-carrier lifetime in p-And n-type kerfless epitaxial (epi) crystalline silicon wafers is shown to increase >500× during phosphorus gettering. We employ kinetic defect simulations and microstructural characterization techniques to elucidate the root cause of this exceptional gettering response. Simulations and deep-level transient spectroscopy (DLTS) indicate that a high concentration of point defects (likely Pt) is "locked in" during fast (60 °C/min) cooling during epi wafer growth. The fine dispersion of moderately fast-diffusing recombination-active point defects limits as-grown lifetime but can also be removed during gettering, confirmed by DLTS measurements. Synchrotron-based X-ray fluorescence microscopy indicates metal agglomerates at structural defects, yet the structural defect density is sufficiently low to enable high lifetimes. Consequently, after phosphorus diffusion gettering, epi silicon exhibits a higher lifetime than materials with similar bulk impurity contents but higher densities of structural defects, including multicrystalline ingot and ribbon silicon materials. Device simulations suggest a solar-cell efficiency potential of this material >23%.

    Original languageEnglish
    Article number065101
    JournalJournal of Applied Physics
    Volume119
    Issue number6
    DOIs
    Publication statusPublished - 14 Feb 2016

    Research Beacons, Institutes and Platforms

    • Photon Science Institute

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