纳米半导体中多重激子效应研究进展  

Recent advance in multiple exciton generation in semiconductor nanocrystals

作　　者：刘长菊[1] 卢敏[1] 苏未安[1] 董太源[1] 沈文忠[2] 

机构地区：[1]江西理工大学理学院,赣州341000 [2]上海交通大学太阳能研究所,物理与天文学院凝聚态光谱与光电子物理实验室,上海200240

出　　处：《物理学报》2018年第2期12-28,共17页Acta Physica Sinica

基　　金：国家自然科学基金(批准号：11464016,11647149)资助的课题

摘　　要：多重激子效应是指纳米半导体吸收一个高能光子后产生两个甚至多个电子-空穴对的物理过程,不仅具有重要的基础研究意义,而且在新型太阳电池及高性能光电子器件领域具有潜在应用价值.综述了多重激子效应的发展历程;总结了纳米半导体的材料组分、体系结构甚至表面质量对多重激子效应的影响;介绍了多重激子效应的实验测试分析方法以及解释多重激子效应的理论方法;概括了目前多重激子效应在器件中的应用并对其应用前景进行展望.The multiple exciton generation（MEG）, a process in which two or even more electron-hole pairs are created in nanostructured semiconductors by absorbing a single high-energy photon, is fundamentally important in many fields of physics, e.g., nanotechnology and optoelectronic devices. Many high-performance optoelectronic devices can be achieved with MEG where quite an amount of the energy of an absorbed photon in excess of the band gap is used to generate morei additional electron-hole pairs instead of rapidly lost heat. In this review, we present a survey on both the research context and the recent progress in the understanding of MEG. This phenomenon has been experimentally observed in the OD nanocrystals, such as PbX（X = Se, S, and Te）, InX（X = As and P）, CdX（X = Se and Te）, Si, Ge, and semi-metal quantum dots, which produce the differential quantum efficiency as high as 90%±10%. Even more remarkably, experiment advances have made it possible to realize MEG in the one-dimensional（1 D） semiconductor nanorods and the twodimensional（2 D） nano-thin films. Theoretically, three different approaches, i.e., the virtual exciton generation approach,the coherent multiexciton mode, and the impact ionization mechanism, have been proposed to explain the MEG effect in semiconductor nanostructures. Experimentally, the MEG has been measured by the ultrafast transient spectroscopy, such as the ultrafast transient absorption, the terahertz ultrafast transient absorption, the transient photoluminescence, and the transient grating technique. It is shown that the properties of nanostructured semiconductors, e.g., the composition,structure and surface of the material, have dramatic effects on the occurrence of MEG. As a matter of fact, it is somewhat hard to experimentally confirm the signature of MEG in nanostructured semiconductors due to two aspects：i） the time scale of the MEG process is very short; ii） the excitation fiuence should be extremely low to prevent the multiexcitons from being generated b

关 键 词：多重激子效应 量子效率 阈值能量 纳米半导体 

分 类 号：O471.1[理学—半导体物理] TM914.4[理学—物理]