Analysis of threshold voltage shift for full vgs /vds /oxygen-content span under positive bias stress in bottom-gate amorphous ingazno thin-film transistors

Je Hyuk Kim, Jun Tae Jang, Jong Ho Bae, Sung Jin Choi, Dong Myong Kim, Changwook Kim, Yoon Kim, Dae Hwan Kim

Research output: Contribution to journalArticlepeer-review

15 Scopus citations

Abstract

In this study, we analyzed the threshold voltage shift characteristics of bottom-gate amorphous indium-gallium-zinc-oxide (IGZO) thin-film transistors (TFTs) under a wide range of positive stress voltages. We investigated four mechanisms: electron trapping at the gate insulator layer by a vertical electric field, electron trapping at the drain-side GI layer by hot-carrier injection, hole trapping at the source-side etch-stop layer by impact ionization, and donor-like state creation in the drain-side IGZO layer by a lateral electric field. To accurately analyze each mechanism, the local threshold voltages of the source and drain sides were measured by forward and reverse read-out. By using contour maps of the threshold voltage shift, we investigated which mechanism was dominant in various gate and drain stress voltage pairs. In addition, we investigated the effect of the oxygen content of the IGZO layer on the positive stress-induced threshold voltage shift. For oxygen-rich devices and oxygen-poor devices, the threshold voltage shift as well as the change in the density of states were analyzed.

Original languageEnglish
Article number327
JournalMicromachines
Volume12
Issue number3
DOIs
StatePublished - Mar 2021

Keywords

  • Donor-like state creation
  • Electron trapping
  • Hole trapping
  • Indium-gallium-zinc-oxide thin-film transistors (-IGZO TFT)
  • Instability
  • Oxygen content

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