Broadening of Distribution of Trap States in PbS Quantum Dot Field-Effect Transistors with High-k Dielectrics

Mohamad I. Nugraha, Roger Häusermann, Shun Watanabe, Hiroyuki Matsui, Mykhailo Sytnyk, Wolfgang Heiss, Jun Takeya*, Maria A. Loi

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

22 Scopus citations

Abstract

We perform a quantitative analysis of the trap density of states (trap DOS) in PbS quantum dot field-effect transistors (QD-FETs), which utilize several polymer gate insulators with a wide range of dielectric constants. With increasing gate dielectric constant, we observe increasing trap DOS close to the lowest unoccupied molecular orbital (LUMO) of the QDs. In addition, this increase is also consistently followed by broadening of the trap DOS. We rationalize that the increase and broadening of the spectral trap distribution originate from dipolar disorder as well as polaronic interactions, which are appearing at strong dielectric polarization. Interestingly, the increased polaron-induced traps do not show any negative effect on the charge carrier mobility in our QD devices at the highest applied gate voltage, giving the possibility to fabricate efficient low-voltage QD devices without suppressing carrier transport.

Original languageEnglish (US)
Pages (from-to)4719-4724
Number of pages6
JournalACS Applied Materials and Interfaces
Volume9
Issue number5
DOIs
StatePublished - Feb 8 2017

Bibliographical note

Publisher Copyright:
© 2017 American Chemical Society.

Keywords

  • field-effect transistors
  • high-k
  • PbS quantum dots
  • polaron
  • trap states

ASJC Scopus subject areas

  • General Materials Science

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