The Effect of Light on Amorphous Silicon Thin Film Transistors based on Photo-Sensor Applications

  • Ha, Tae-Jun (School of Electrical Engineering and Computer Science, Seoul National University) ;
  • Park, Hyun-Sang (School of Electrical Engineering and Computer Science, Seoul National University) ;
  • Kim, Sun-Jae (School of Electrical Engineering and Computer Science, Seoul National University) ;
  • Lee, Soo-Yeon (School of Electrical Engineering and Computer Science, Seoul National University) ;
  • Han, Min-Koo (School of Electrical Engineering and Computer Science, Seoul National University)
  • Published : 2009.10.12

Abstract

We have investigated the effect of light on amorphous silicon thin film transistors based photo-sensor applications. We have analyzed the instability caused by electrical gate bias stresses under the light illumination and the effect of photo-induced quasi-annealing on the instability. Threshold voltage ($V_{TH}$) under the negative gate bias stress with light illumination was more decreased than that under the negative gate bias stress without light illumination even though $V_{TH}$ caused by the light-induced stress without negative gate bias was shifted positively. These results are because the increase of carrier density in a channel region caused by the light illumination has the enhanced effect on the instability caused by negative gate bias stress. The prolonged light illumination led to the recovery of shifted VTH caused by negative gate bias stress under the light illumination due to the recombination of trapped hole charges.

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