Clarendon Laboratory, Department of Physics, University of Oxford, Oxford, OX1 3PU, United Kingdom.
Nano Lett. 2012 Oct 10;12(10):5325-30. doi: 10.1021/nl3026828. Epub 2012 Sep 13.
Using transient terahertz photoconductivity measurements, we have made noncontact, room temperature measurements of the ultrafast charge carrier dynamics in InP nanowires. InP nanowires exhibited a very long photoconductivity lifetime of over 1 ns, and carrier lifetimes were remarkably insensitive to surface states despite the large nanowire surface area-to-volume ratio. An exceptionally low surface recombination velocity (170 cm/s) was recorded at room temperature. These results suggest that InP nanowires are prime candidates for optoelectronic devices, particularly photovoltaic devices, without the need for surface passivation. We found that the carrier mobility is not limited by nanowire diameter but is strongly limited by the presence of planar crystallographic defects such as stacking faults in these predominantly wurtzite nanowires. These findings show the great potential of very narrow InP nanowires for electronic devices but indicate that improvements in the crystallographic uniformity of InP nanowires will be critical for future nanowire device engineering.
利用瞬态太赫兹光电导测量，我们在室温下对 InP 纳米线中的超快载流子动力学进行了非接触式测量。InP 纳米线表现出超过 1 ns 的非常长的光电导寿命，并且尽管纳米线的表面积与体积比很大，但载流子寿命对表面态的影响非常小。在室温下记录到的表面复合速度极低（170 cm/s）。这些结果表明，InP 纳米线是光电设备，特别是光伏设备的理想候选材料，而无需表面钝化。我们发现载流子迁移率不受纳米线直径的限制，而是受到平面晶体缺陷（如这些主要为纤锌矿结构的纳米线中的位错）的强烈限制。这些发现表明，非常窄的 InP 纳米线在电子器件中有很大的潜力，但表明提高 InP 纳米线的晶体均匀性对于未来的纳米线器件工程至关重要。
