title: In spite of recent doubts carrier multiplication does occur in PbSe nanocrystals.
abstract: 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.
authors.affiliation: Optoelectronic Materials, Faculty of Applied Sciences, Delft University of Technology, Delft, The Netherlands.
authors.forename: M Tuan
authors.initials: MT
authors.lastname: Trinh
authors.forename: Arjan J
authors.initials: AJ
authors.lastname: Houtepen
authors.forename: Juleon M
authors.initials: JM
authors.lastname: Schins
authors.forename: Tobias
authors.initials: T
authors.lastname: Hanrath
authors.forename: Jorge
authors.initials: J
authors.lastname: Piris
authors.forename: Walter
authors.initials: W
authors.lastname: Knulst
authors.forename: Albert P L M
authors.initials: AP
authors.lastname: Goossens
authors.forename: Laurens D A
authors.initials: LD
authors.lastname: Siebbeles
mesh_terms: D003198:Computer Simulation; D003460:Crystallization / Q000379:methods*; D004579:Electron Transport; D007854:Lead / Q000737:chemistry*; D046911:Macromolecular Substances / Q000737:chemistry; D008422:Materials Testing; D008956:Models, Chemical; D008968:Molecular Conformation; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure*; D036103:Nanotechnology / Q000379:methods*; D010316:Particle Size; D018036:Selenium Compounds / Q000737:chemistry*; D013499:Surface Properties
chemical_list: D046911:Macromolecular Substances; D018036:Selenium Compounds; C088065:lead selenide; D007854:Lead