Prof. Keshav M. Dani, Femtosecond Spectroscopy Unit, Okinawa Inst. of Sci. & Tech. Graduate Univ., 1919-1 Tancha, Onna-son, Okinawa, Japan 904-0495
The flow of electrons in materials drives much of technology today – from our ability to generate electricity from light in solar cell devices, to transistors in modern computing machines. The ability to directly image the flow of this charge promises to deepen our understanding of the fundamental processes involved and impact future technology. However, imaging the motion of charge requires sophisticated techniques with simultaneous high spatial and high temporal resolution. By combining the femtosecond temporal resolution offered by ultrafast optical techniques, with the nanoscale spatial resolution afforded by photoemission electron microscopy, we make a movie – lasting just a few trillionths of a second, of the motion of electrons after light is absorbed in a solar cell structure, thus capturing the essence of a very important 21st century technology . We will end by discussing how our movie and the technique in general can contribute to future understanding of physical phenomena at the nano-, femto- scale.
 Man, M., et al., Nature Nanotech. 12, 36-40 (2017)
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