Identifying and Investigating Spatial Features in InGaAs Solar Cells by Hyperspectral Luminescence Imaging

Hyperspectral luminescence imaging adds high-resolution spectral data to electroluminescence and photoluminescence images of photovoltaic materials and devices. This enables absolute calibration across a range of spectra, and subsequently enhances the information that can be gained from such measurements. We present a temperature-dependent luminescence hyperspectral imaging study of dilute InGaAs solar cells. We are able to identify the cause of dark spots on the device as local areas with increased defect-related recombination and identify a likely candidate for the type of defect. Hyperspectral images also reveal a device-wide pattern in low-energy-tail luminescence and In alloy fraction, which corresponds with increased nonradiative recombination. This pattern would not be identifiable with conventional imaging methods. Detailed information on such features is useful as, paired with knowledge of fabrication processes and device design features, it can help identify ways to reduce associated non-radiative recombination and improve device performance.