In spite of recent doubts carrier multiplication does occur in PbSe nanocrystals
In spite of recent doubts carrier multiplication does occur in PbSe nanocrystals
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DOI：
10.1021/nl0807225
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发表时间：
2008-06-01
期刊：
影响因子：
10.8
通讯作者：
Siebbeles, Laurens D. A.
中科院分区：
文献类型：
--
作者：
Trinh, M. Tuan;Houtepen, Arian J.;Siebbeles, Laurens D. A.
已报道了几种半导体纳米晶体的高效载流子倍增：PbSe、PbS、PbTe、CdSe、InAs 和 Si。其中一些报告受到了研究的质疑，这些研究声称载流子倍增不会在 CdSe、CdTe 和 InAs 纳米晶体中发生，从而对其余材料中载流子倍增的发生提出了合理的怀疑。在这里，使用飞秒瞬态光漂白给出了其在 PbSe 纳米晶体中出现的确凿证据。此外，结果表明，正确确定载流子倍增效率需要对光漂白特征进行光谱积分。我们获得的载流子倍增效率明显低于之前报道的，并且纳米晶体中的载流子倍增效率是否比块体半导体中的载流子倍增效率更高仍然是一个悬而未决的问题。
Efficient carrier multiplication has been reported for several semiconductor nanocrystals: PbSe, PbS, PbTe, CdSe, InAs, and Si. Some of these reports have been challenged by studies claiming that carrier multiplication does not occur in CdSe, CdTe, and InAs nanocrystals, thus raising legitimate doubts concerning the occurrence of carrier multiplication in the remaining materials. Here, conclusive evidence is given for its occurrence in PbSe nanocrystals using femtosecond transient photobleaching. In addition, it is shown that a correct determination of carrier-multiplication efficiency requires spectral integration over the photobleach feature. The carrier multiplication efficiency we obtain is significantly lower than what has been reported previously, and it remains an open question whether it is higher in nanocrystals than it is in bulk semiconductors.