Direct Imaging of Free Carrier and Trap Carrier Motion in Silicon Nanowires by Spatially-Separated Femtosecond Pump-Probe Microscopy

作者：Gabriel Michelle M; Kirschbrown Justin R; Christesen Joseph D; Pinion Christopher W; Zigler David F; Grumstrup Erik M; Mehl Brian P; Cating Emma E M; Cahoon James F^*; Papanikolas John M

来源：Nano Letters, 2013, 13(3): 1336-1340.

DOI：10.1021/nl400265b

• Ultrafast microscopy
• silicon nanowire
• carrier diffusion
• pump-probe spectroscopy

We have developed a pump probe microscope capable of exciting a single semiconductor nanostructure in one location and probing it in another with both high spatial and temporal resolution. Experiments performed on Si nanowires enable a direct visualization of the charge cloud produced by photoexcitation at a localized spot as it spreads along the nanowire axis. The time-resolved images show clear evidence of rapid diffusional spreading and recombination of the free carriers, which is consistent with ambipolar diffusion and a surface recombination velocity of similar to 10(4) cm/s. The free carrier dynamics are followed by trap carrier migration on slower time scales.

• 出版日期2013-3