Intrinsic electron-glass effects in strongly localized Tl 2O3-x films

Z. Ovadyahu*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

13 Scopus citations

Abstract

Transport measurements made on films of thallium-oxide (n-type semiconductor) are presented and discussed. The focus in this work is on the strongly-localized regime where charge transport is by variable-range hopping. It is demonstrated that, at liquid-helium temperatures, these films exhibit all the characteristic features of intrinsic electron glasses. These include a slow (logarithmic in time) conductance relaxation that may be induced by any of the following protocols: Quench cooling from high temperatures, sudden change of gate voltage, exposure to infrared radiation, and stressing the system with a non-Ohmic field. The microstructure of the films are characterized by electron microscopy and their carrier concentration are measured by Hall effect. Field-effect experiments reveal a memory dip that has a width compatible with the carrier concentration of the system as compared with previously studied electron glasses. It is observed that the common ingredient in all the systems that exhibit electron-glass effects is high carrier concentration suggesting that their localized sites may be multioccupied even when deep into the insulating regime. That lightly-doped semiconductors do not show intrinsic electron-glass effects is consistent with this empirical observation. The connection between the memory dip and the Coulomb gap is discussed in light of these findings.

Original languageEnglish
Article number085106
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume88
Issue number8
DOIs
StatePublished - 7 Aug 2013

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