Title: Four-dimensional imaging of carrier interface dynamics in p-n junctions
Authors: Najafi, Ebrahim
Scarborough, Timothy D.
Tang, Jau
Zewail, Ahmed
Department of Photonics
Issue Date: 9-Jan-2015
Abstract: The dynamics of charge transfer at interfaces are fundamental to the understanding of many processes, including light conversion to chemical energy. Here, we report imaging of charge carrier excitation, transport, and recombination in a silicon p-n junction, where the interface is well defined on the nanoscale. The recorded images elucidate the spatiotemporal behavior of carrier density after optical excitation. We show that carrier separation in the p-n junction extends far beyond the depletion layer, contrary to the expected results from the widely accepted drift-diffusion model, and that localization of carrier density across the junction takes place for up to tens of nanoseconds, depending on the laser fluence. The observations reveal a ballistic-type motion, and we provide a model that accounts for the spatiotemporal density localization across the junction.
URI: http://dx.doi.org/10.1126/science.aaa0217
ISSN: 0036-8075
DOI: 10.1126/science.aaa0217
Journal: SCIENCE
Volume: 347
Issue: 6218
Begin Page: 164
End Page: 167
Appears in Collections:Articles