The geometry effect on threshold voltage of top-contact and bottom contact pentacene based thin film transistors

Yu Wu Wang, De Zhi Liu, Ming Yue Hong, Horng-Long Cheng

Research output: Chapter in Book/Report/Conference proceedingConference contribution

1 Citation (Scopus)


In this article, we fabricated a series of different geometries for pentacene based thin film transistors (TFTs), including top contact (TC) and bottom contact (BC) configurations, to monitor variations in characteristics. The threshold voltage (Vth) in the saturation regime shifted toward a positive voltage, i.e., from 0.5, 3.2, 9.1, 12.1, and 19.5 V for the channel lengths 67, 47, 23, 19, and 15 μm, respectively, in BC TFTs. All of the TFTs were operated in depletion mode. However, the Vth in the linear regime shifted from -9.3, -9.0, -3.8, -1.8, and 1.5 V for the same devices. Most of the TFTs in the linear regime were operated in enhanced mode. The phenomenon is believed to be strongly correlated with the longitudinal electric field (VDS/L). The high VDS induces a high carrier injection, which makes the pentacene TFTs behave like a depletion type transistor. This assumption is evidenced by the low carrier injection with small VDS results. The device configuration and space charge region must be discussed in more detail. Furthermore, the field effect mobility variation and structure configuration effect is discussed in more detail within the full manuscript.

Original languageEnglish
Title of host publicationOrganic Field-Effect Transistors VIII
Publication statusPublished - 2009 Dec 1
EventOrganic Field-Effect Transistors VIII - San Diego, CA, United States
Duration: 2009 Aug 32009 Aug 5

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
ISSN (Print)0277-786X


OtherOrganic Field-Effect Transistors VIII
Country/TerritoryUnited States
CitySan Diego, CA

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering


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