Photoresponsivity Enhancement and Extension of the Detection Spectrum for Amorphous Oxide Semiconductor Based Sensors

Dun Bao Ruan, Po-Tsun Liu*, Yi Heng Chen, Yu Chuan Chiu, Ta Chun Chien, Min Chin Yu, Kai Jhih Gan, Simon M. Sze

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

26 Scopus citations


In this study, indium gallium zinc oxide (InGaZnO [IGZO]) active layer capped with an ultrathin p-type stannous oxide (SnO) is demonstrated to be a thin film transistor (TFT) for color scanning and photosensing device applications. Typically, the sole IGZO-based TFT is blind to visible light and hard to be developed for visible light sensing. The combination of IGZO and SnO layers can extend the light detection spectrum into visible light wavelengths and ameliorate the photosensing characteristics. The optical responsivity and signal to noise ratio can even be enhanced from 1.05 × 10 −2 to 398.02 A W −1 and from 2.1 × 10 1 to 6.8 × 10 5 with at least four orders of magnitude, respectively. With the detailed material analysis and physical model discussed, it suggests that the large amount of additional light-excited carrier generated in the capping layer is the key factor for the significant improvement. Furthermore, the phenomenon of persistent photoconductivity can be effectively suppressed by its natural recombination under the heterojunction structure without applying charge-pumping method. The electrical uniformity of the sensor device is also highly potential for the next-generation displays integrating the photosensing functions.

Original languageEnglish
Article number1800824
JournalAdvanced Electronic Materials
Issue number3
StatePublished - Mar 2019


  • detection spectrum
  • in-cell photosensors
  • photoresponsivity
  • thin film transistors
  • ultrathin light-absorbing layers


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