Optical Properties of a-SiGe:H Thin Film Transistor for Infrared Image Sensors in Touch Sensing Display

We report the effects of monochromatic illumination on the electrical performance of a-SiGe:H thin-film transistor (TFT) and the use of this device as infrared (IR) image-sensing touch displays. In order to reduce the inevitable incidence of visible light into device, the visible cutting layer was d...

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Bibliographic Details
Published in:Journal of display technology 2012-10, Vol.8 (10), p.617-622
Main Authors: Han, Sang Youn, Park, Kyung Tea, Jeon, Ho Sik, Heo, Yang Wook, Bae, Byung Seong
Format: Article
Language:English
Subjects:
Amorphous SiGe
Band pass filters
Devices
Diodes
Glass
infrared (IR) detector
Infrared radiation
LCDs
Light emitting diodes
Liquid crystal displays
Optical noise
Optical sensors
photosensor
Semiconductor devices
Thin film transistors
Thin films
thin-film transistor (TFT)
Touch
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Summary:We report the effects of monochromatic illumination on the electrical performance of a-SiGe:H thin-film transistor (TFT) and the use of this device as infrared (IR) image-sensing touch displays. In order to reduce the inevitable incidence of visible light into device, the visible cutting layer was designed, which played a critical role in reducing the optical noise from visible light. When the photo response was observed in real liquid crystal display (LCD) operation environment, it showed the display contents dependence, meaning that the supply of external IR light source for the touch sensing would be effective independent of any ambient light condition. Additionally, the optical noise from the display operation was eliminated using the block operation as well as the backlight IR light-emitting diode (LED) light modulation. From these, the clear touch images were successfully obtained in the a-SiGe:H photosensor embedded LCD panel.
ISSN:1551-319X
1558-9323
DOI:10.1109/JDT.2012.2209171