Direct Imaging of Free Carrier and Trap Carrier Motion in Silicon Nanowires by Spatially-Separated Femtosecond Pump-Probe Microscopy
Direct Imaging of Free Carrier and Trap Carrier Motion in Silicon Nanowires by Spatially-Separated Femtosecond Pump-Probe Microscopy
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DOI：
10.1021/nl400265b
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发表时间：
2013-03-01
期刊：
影响因子：
10.8
通讯作者：
Papanikolas, John M.
中科院分区：
文献类型：
--
作者：
Gabriel, Michelle M.;Kirschbrown, Justin R.;Papanikolas, John M.
我们开发了一种泵浦探测显微镜，能够在一个位置激发单个半导体纳米结构，并在另一个位置以高空间和时间分辨率探测它。在硅纳米线上进行的实验使人们能够直接看到光激发在局部点产生的电荷云，因为它沿着纳米线轴扩散。时间分辨图像清楚地显示了自由载流子的快速扩散和复合，这与双极扩散相一致，表面复合速度接近10(4)cm/S，在较慢的时间尺度上遵循自由载流子动力学和陷阱载流子迁移。
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.