Light-Controlled Gap-Type TFT Used for Large-Area Under-Screen Fingerprint Sensor

Ya Hsiang Tai, Cheng Che Tu, Yi Cheng Yuan, Yu Jia Chang, Mao Hsiu Hsu, Che Yu Chuang*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

12 Scopus citations


In the fierce market competition of different biometric methods in smartphones, where consumers are pursuing a high screen ratio, optical fingerprint recognition under OLED screen is a well-established approach. However, using thin-film transistor (TFT) technology to make large-area optical sensors generally has the issue of low sensitivity, which will make the signal difficult to be read out. In this paper, we propose to use gap-type TFT with high photosensitivity current and process compatible with display panels as the sensing device to build the sensing array. The pixel circuit can be simplified to structure containing only of two thin-film transistors (TFTs). Using this gap-type TFT sensing array under OLED panel for fingerprint recognition is proven to be effective by the clear images captured with the readout system.

Original languageEnglish
Article number9419857
Pages (from-to)517-520
Number of pages4
JournalIEEE Journal of the Electron Devices Society
StatePublished - May 2021


  • Fingerprint sensor
  • gap-type
  • photocurrent
  • thin film transistor (TFT)


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