Mechanisms for intraband energy relaxation in semiconductor quantum dots: The role of electron-hole interactions
Mechanisms for intraband energy relaxation in semiconductor quantum dots: The role of electron-hole interactions
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DOI：
10.1103/physrevb.61.r13349
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发表时间：
2000-05-15
影响因子：
3.7
通讯作者：
Bawendi, MG
中科院分区：
文献类型：
--
作者：
Klimov, VI;Mikhailovsky, AA;Bawendi, MG
为了评估量子点中非声子能量弛豫机制的作用，特别是电子-空穴 (e-h) 相互作用的作用，我们研究了 CdSe 胶体纳米颗粒中的飞秒载流子动力学，其中使用不同类型的表面配体控制 e-h 分离（耦合）。在用空穴接受分子封端的点中，在空穴转移到封端基团后，e-h 耦合大大减少。通过在空穴转移的不同阶段重新激发导带内的电子并监测其弛豫回到基态，我们观察到空穴转移完成后电子弛豫时间增加了十倍以上（从 250 fs 到 3 ps）。这强烈表明量子点中的电子弛豫不是由声子发射主导，而是由 e-h 能量转移主导。
To evaluate the role of nonphonon energy relaxation mechanisms in quantum dots and in particular the role of electron-hole (e-h) interactions, we have studied femtosecond carrier dynamics in CdSe colloidal nanoparticles in which the e-h separation (coupling) is controlled using different types of surface ligands. In dots capped with hole accepting molecules, the e-h coupling is strongly reduced after the hole is transferred to a capping group. By re-exciting an electron within the conduction band at different stages of hole transfer and monitoring its relaxation back into the ground state, we observe a more than tenfold increase in the electron relaxation time (from 250 fs to 3 ps) after the completion of the hole transfer to the capping molecule. This strongly indicates that electron relaxation in quantum dots is dominated not by phonon emission but by the e-h energy transfer.