Density of states measured by scanning-tunneling spectroscopy sheds new light on the optical transitions in PbSe nanocrystals

Peter Liljeroth (1) , P.A. Zeijlmans van Emmichoven (1) , Stephen G. Hickey (2) , Horst Weller (2) , B. Grandidier (3) , Guy Allan (3) , Daniel Vanmaekelbergh (1)

1 HU - University of Applied Sciences [Utrecht]
2 Hamburg University of Applied Sciences [Hamburg]
3 IEMN - Institut d’Électronique, de Microélectronique et de Nanotechnologie - UMR 8520

The density-of-states function of individual colloidal PbSe nanocrystals varying in diameter between 3 and 7 nm is measured by resonant tunneling spectroscopy. It is in semiquantitative agreement with tight-binding calculations, but the energy separation between electron (hole) levels of S and P symmetry is systematically smaller than predicted by the theory. These results provide an explanation for the second and third excitonic optical transitions, which have been debated for a long time.

Domaines: Sciences de l'ingénieur [physics]

Peter Liljeroth, P.A. Zeijlmans van Emmichoven, Stephen G. Hickey, Horst Weller, B. Grandidier, et al.. Density of states measured by scanning-tunneling spectroscopy sheds new light on the optical transitions in PbSe nanocrystals. Physical Review Letters, 2005, 95, pp.086801/1-4. ⟨hal-00126240⟩