Density of states and conductivity of a granular metal or an array of quantum dots

Jingshan Zhang, Boris I. Shklovskii

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103 Scopus citations

Abstract

The conductivity of a granular metal or an array of quantum dots usually has the temperature dependence associated with variable range hopping within the soft Coulomb gap of density of states. This is difficult to explain because neutral dots have a hard charging gap at the Fermi level. We show that uncontrolled or intentional doping of the insulator around dots by donors leads to random charging of dots and finite bare density of states at the Fermi level. Then Coulomb interactions between electrons of distant dots results in a soft Coulomb gap. We show that in a sparse array of dots the bare density of states oscillates as a function of concentration of donors and causes periodic changes in the temperature dependence of conductivity. In a dense array of dots the bare density of states is totally smeared if there are several donors per dot in the insulator.

Original languageEnglish (US)
Article number115317
Pages (from-to)115317-1-115317-13
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume70
Issue number11
DOIs
StatePublished - Sep 2004

Bibliographical note

Funding Information:
The authors are grateful to M. V. Entin, M. M. Fogler, Yu. M. Galperin, A. Kamenev, and A. I. Larkin for helpful discussions. This work was partially supported by NSF No. DMR-9985785.

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