A combined transient and steady state approach for robust lifetime spectroscopy with micrometer resolution

We present the combination of two complementary micro-photoluminescence spectroscopic techniques operating in transient and steady state condition, respectively. Introducing the time domain into the well-established micro-photoluminescence mapping approach operating under steady state conditions demonstrates a distinct improvement of the robustness and reliability in the determination of charge carrier lifetime measured with micrometer spatial resolution. Lifetimes from 50 ns to above ms are accessible. We elaborate a calibration procedure and apply the combined all-photoluminescence setup to high-performance multicrystalline silicon. A lifetime image obtained from the established photoluminescence imaging technique is reconstructed from the microscopic map by considering lateral diffusion and optical blurring, revealing a more detrimental influence of small angle grain boundaries as well as a higher lifetime within grains as may be deduced from the standard imaging technique. (© 2015 WILEY-VCH Verlag GmbH &Co. KGaA, Weinheim)