Dynamic Charge Carrier Trapping in Quantum Dot Field Effect Transistors

Yingjie Zhang, Qian Chen, A. Paul Alivisatos, Miquel Salmeron

Research output: Contribution to journalArticlepeer-review


Noncrystalline semiconductor materials often exhibit hysteresis in charge transport measurements whose mechanism is largely unknown. Here we study the dynamics of charge injection and transport in PbS quantum dot (QD) monolayers in a field effect transistor (FET). Using Kelvin probe force microscopy, we measured the temporal response of the QDs as the channel material in a FET following step function changes of gate bias. The measurements reveal an exponential decay of mobile carrier density with time constants of 3-5 s for holes and ∼10 s for electrons. An Ohmic behavior, with uniform carrier density, was observed along the channel during the injection and transport processes. These slow, uniform carrier trapping processes are reversible, with time constants that depend critically on the gas environment. We propose that the underlying mechanism is some reversible electrochemical process involving dissociation and diffusion of water and/or oxygen related species. These trapping processes are dynamically activated by the injected charges, in contrast with static electronic traps whose presence is independent of the charge state. Understanding and controlling these processes is important for improving the performance of electronic, optoelectronic, and memory devices based on disordered semiconductors.

Original languageEnglish (US)
Pages (from-to)4647-4663
Number of pages17
JournalNano letters
Issue number7
StatePublished - Jul 8 2015
Externally publishedYes


  • Colloidal quantum dot
  • bias stress
  • charge transport
  • dynamic charge trapping
  • field effect transistor
  • hysteresis

ASJC Scopus subject areas

  • Bioengineering
  • General Chemistry
  • General Materials Science
  • Condensed Matter Physics
  • Mechanical Engineering


Dive into the research topics of 'Dynamic Charge Carrier Trapping in Quantum Dot Field Effect Transistors'. Together they form a unique fingerprint.

Cite this