Understanding the electronic structure of doped semiconductors is essential to realize advancements in electronics that assist with efficient and sustainable energy use and generation. We have examined the transient interaction of an excess charge carrier with a guest ion in a semiconductor matrix using time resolved X-ray absorption spectroscopy. Specifically, photoexcitation of copper-doped cadmium sulfide nanoparticles resulted in an energy shift of the Cu K-edge XANES absorption due to capture of a hole by the dopant in the interior of the particle. This in turn instigates a stronger bonding interaction of copper with sulfur within the semiconductor host as revealed by the excited state EXAFS spectrum. X-ray analyses also revealed two types of surface-bound copper ions that display different dynamics in the excited state. These observations are supported by large-scale DFT calculations, which attest to the generality of the conclusions made with this system. Overall, the modulation of the bonding of dopants by electrons and holes represents a new dynamic that has implications for understanding the mobility of charge carriers in semiconductor hosts.

Charge carriers modulate the bonding of semiconductor dopants: A time-resolved x-ray study

254th National Meeting (2017)

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