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Article Dans Une Revue ChemPhysChem Année : 2003

Long-range transport in an assembly of ZnO quantum dots : the effects of quantum confinement, Coulomb repulsion and structural disorder

Résumé

We have studied the storage and long-range transport of electrons in a porous assembly of weakly coupled ZnO quantum dots permeated with an aqueous and a propylene carbonate electrolyte solution. The number of electrons per ZnO quantum dot is controlled by the electrochemical potential of the assembly; the charge of the electrons is compensated by ions present in the pores. We show with optical and electrical measurements that the injected electrons occupy the S, P, and D type conduction electron levels of the quantum dots; electron storage in surface states is not important. With this method of three-dimensional charge compensation, up to ten electrons per quantum-dot can be stored if the assembly is permeated with an aqueous electrolyte. The screening of the electron charge is less effective in the case of an assembly permeated with a propylene carbonate electrolyte solution. Long-range electron transport is studied with a transistor set-up. In the case of ZnO assemblies permeated with an aqueous electrolyte, two quantum regimes are observed corresponding to multiple tunnelling between the S orbitals (at a low occupation) and P orbitals (at a higher occupation). In a ZnO quantum-dot assembly permeated with a propylene carbonate electrolyte solution, there is a strong overlap between these two regimes.

Dates et versions

hal-00146618 , version 1 (15-05-2007)

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Aarnoud L. Roest, Alexander Germeau, John J. Kelly, Daniel Vanmaekelbergh, Guy Allan, et al.. Long-range transport in an assembly of ZnO quantum dots : the effects of quantum confinement, Coulomb repulsion and structural disorder. ChemPhysChem, 2003, 4, pp.959-966. ⟨10.1002/cphc.200300696⟩. ⟨hal-00146618⟩
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