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

Abstract

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.Index Terms-Amorphous SiGe, infrared (IR) detector, photosensor, thin-film transistor (TFT).

Photosensitivity enhancement in hydrogenated amorphous silicon thin-film phototransistors with gate underlap

“…2 An infrared (IR) photosensor composed of photodiode or phototransistor array might be most suitable for actual applications because it can easily detect user's motion with or without physical contact and map into images from the input signals. [3][4][5] Some important properties required for photosensors are low cost, high sensitivity, and the integration of sensors into active matrix display backplane. In this regard, hydrogenated amorphous silicon (A-Si:H) based devices have been considered and adopted as a strong candidate for various photosensor applications due to the favorable properties for the requirements mentioned above.…”

Patterned Cu-Mesh-Based Transparent and Wearable Touch Panel for Tactile, Proximity, Pressure, and Temperature Sensing

“…2 The mechanisms include resistive, 6,7 capacitive, 8,9 piezoelectric, 10,11 surface acoustic, 12,13 and infrared signals. 14 The triboelectric nanogenerator (TENG) has also been utilized for touch sensing with multifunctionality. 15 Among these, capacitive sensing is considered to be highly reliable because it offers a multitouch possibility with the desired resolution and less cross talk.…”

“…There are many ways of performing touch sensing . The mechanisms include resistive, , capacitive, , piezoelectric, , surface acoustic, , and infrared signals . The triboelectric nanogenerator (TENG) has also been utilized for touch sensing with multifunctionality .…”