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  • Increased Throughput and Se...
    Morishige, Ashley E.; Laine, Hannu S.; Looney, Erin E.; Jensen, Mallory A.; Vogt, Stefan; Li, Joel B.; Lai, Barry; Savin, Hele; Buonassisi, Tonio

    IEEE journal of photovoltaics, 05/2017, Letnik: 7, Številka: 3
    Journal Article

    Optimizing photovoltaic (PV) devices requires characterization and optimization across several length scales, from centimeters to nanometers. Synchrotron-based micro-X-ray fluorescence spectromicroscopy (μ-XRF) is a valuable link in the PV-related material and device characterization suite. μ-XRF maps of elemental distributions in PV materials have high spatial resolution and excellent sensitivity and can be measured on absorber materials and full devices. Recently, we implemented on-the-fly data collection (flyscan) at Beamline 2-ID-D at the Advanced Photon Source at Argonne National Laboratory, eliminating a 300 ms per-pixel overhead time. This faster scanning enables high-sensitivity (~10 14 atoms/cm 2 ), large-area (10 000s of μm 2 ), high-spatial resolution (<;200 nm scale) maps to be completed within a practical scanning time. We specifically show that when characterizing detrimental trace metal precipitate distributions in multicrystalline silicon wafers for PV, flyscans can increase the productivity of μ-XRF by an order of magnitude. Additionally, flyscan μ-XRF mapping enables relatively large-area correlative microscopy. As an example, we map the transition metal distribution in a 50 μm-diameter laser-fired contact of a silicon solar cell before and after lasing. While we focus on μ-XRF of mc-Si wafers for PV, our results apply broadly to synchrotron-based mapping of PV absorbers and devices.