Feasibility of Transparent Active-Matrix Touch-Screen Displays Demonstrated
Journal
삼성학회
Date
2011.11.07
Abstract
We have built a photo sensor using an array of amorphous oxide semiconductor-based thin film
transistors (TFT) which has a frame rate of 150 Hz and demonstrates the feasibility of transparent
active-matrix touch-screen displays. Amorphous oxide semiconductors are well known for their
optical transparency and their material composition can be tailored to enhance optical absorption
and make them photoconductive at green or shorter wavelengths. However, this photoconductivity
remains for hours after illumination has been removed, which severely degrades the response time,
and hence the frame rate in active matrix TFT-based arrays. We have solved this problem of
persistent photoconductivity (PPC) by using a gated photosensor (photo-TFT) that can provide
direct control over the Fermi level position. This allows a short duration (10 ns) voltage pulse
to erase the PPC by inducing electron accumulation to accelerate the recombination of ionized
oxygen vacancy sites, which are thought to cause PPC.