Surface-induced time-dependent instability of ZnO based thin-film transistors

Ki tae Kim, Kimoon Lee, Min Suk Oh, C. H. Park, Seongil Im

Research output: Contribution to journalArticlepeer-review

25 Citations (Scopus)


We report on the surface-induced time-dependent instability of ZnO based thin-film transistors (ZnO-TFTs) with interdigitated source/drain (S/D) electrodes. As time elapsed, a considerable shift of threshold voltage (VT) was observed (by ~ - 16 V) from our TFT. Contact angle of de-ionized water on ZnO surface also changed from 30° to 110°, revealing time-dependent surface state change. According to X-ray photoemission spectroscopy (XPS) measurements, the Zn 2p3/2 core-level peak and the valence band maximum (VBM) of aged ZnO surface shifted to the higher binding energy by 0.3 eV, which implies a downward energy band bending of the ZnO back channel-surface. We conclude that without passivation layer any bottom gate ZnO-TFT meets the surface-induced electrical instabilities due to the time-dependent conductance of ZnO surface.

Original languageEnglish
Pages (from-to)6345-6348
Number of pages4
JournalThin Solid Films
Issue number23
Publication statusPublished - 2009 Oct 1

Bibliographical note

Funding Information:
This work was supported by the fundamental R&D Program for Core Technology of Materials funded by the Ministry of Commerce, Industry and Energy, KOSEF (R01-2006-000-11277-0), the IT R&D program of MKE/IITA [2006-S079-02, Smart window with transparent electronic devices], and Brain Korea 21 Program.

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films
  • Metals and Alloys
  • Materials Chemistry


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