Effects of (NH4)2Sx treatment on the surface properties of SiO2 as a gate dielectric for pentacene thin-film transistor applications

Cheng Chun Hung, Yow Jon Lin

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Abstract

The effect of (NH4)2Sx treatment on the surface properties of SiO2 is studied. (NH4)2Sx treatment leads to the formation of S-Si bonds on the SiO2 surface that serves to reduce the number of donor-like trap states, inducing the shift of the Fermi level toward the conduction band minimum. A finding in this case is the noticeably reduced value of the SiO2 capacitance as the sulfurated layer is formed at the SiO2 surface. The effect of SiO2 layers with (NH4)2Sx treatment on the carrier transport behaviors for the pentacene/SiO2-based organic thin-film transistor (OTFT) is also studied. The pentacene/as-cleaned SiO2-based OTFT shows depletion-mode behavior, whereas the pentacene/(NH4)2Sx-treated SiO2-based OTFT exhibits enhancement-mode behavior. Experimental identification confirms that the depletion-/enhancement-mode conversion is due to the dominance competition between donor-like trap states in SiO2 near the pentacene/SiO2 interface and acceptor-like trap states in the pentacene channel. A sulfurated layer between pentacene and SiO2 is expected to give significant contributions to carrier transport for pentacene/SiO2-based OTFTs.

Original languageEnglish
Article number015101
JournalMaterials Research Express
Volume5
Issue number1
DOIs
Publication statusPublished - 2018 Jan

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All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Biomaterials
  • Surfaces, Coatings and Films
  • Polymers and Plastics
  • Metals and Alloys

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