Ultrafast Transient Absorption Measurements of Charge Carrier Dynamics in Single II-VI Nanowires
Ultrafast Transient Absorption Measurements of Charge Carrier Dynamics in Single II-VI Nanowires
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DOI：
10.1021/jp907147y
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发表时间：
2009-11-05
影响因子：
3.7
通讯作者：
Hartland, Gregory V.
中科院分区：
文献类型：
--
作者：
Carey, Christopher R.;Yu, Yanghai;Hartland, Gregory V.
在接近衍射极限的空间分辨率下，对单根CdTe和CdSe纳米线进行了超快的瞬时吸收实验。结果表明，CdTe纳米线的轨迹表现出快速的皮秒时间尺度动力学，这与表面态的载流子俘获有关。对于不同的纳米线，时间常数是不同的，这归因于陷阱态的能量和/或密度的不同，推测是由于表面化学的不同。在相同条件下对CdSe纳米线进行的实验中不存在快衰减成分，这与CdSe纳米线的发射量子产额比CdTe纳米线高得多是一致的。实验中还将泵浦和探测器放置在一根CdTe纳米线上的不同位置。这些轨迹显示了不同的捕获时间，由于陷阱态能量和/或密度的空间变化，这些结果突出了单粒子测量对这些系统的重要性。
Ultrafast transient absorption experiments have been performed on single CdTe and CdSe nanowires with close to diffraction-limited spatial resolution The traces for the CdTe nanowires show fast picosecond time scale dynamics, which is assigned to charge carrier trapping at surface states. The time constants vary for different nanowires This is attributed to differences in the energy and/or density of the trap states, presumably due to variations in surface chemistry. The fast decay component is absent in experiments on CdSe nanowires performed under identical conditions, which is consistent with the much higher emission quantum yield of CdSe nanowires compared to CdTe nanowires Experiments were also performed with the pump and probe positioned at different points along a single CdTe nanowire. The traces show different trapping times, due to spatial variation in the energy and/or density of trap states These results highlight the importance of single particle measurements for these systems.