Dual-Gate Photosensitive a-Si:H TFT Array Enabling Fingerprint-Sensor-Integrated Display Application

This paper reports on an integrative approach to a fingerprint sensor for an active matrix liquid crystal display (AMLCD). By redesigning the current driver hydrogenated amorphous silicon (a-Si:H) thin-film transistor (TFT) in the display pixel and making it a dual-gate photosensitive TFT with a π-shape channel, a fingerprint-sensor-integrated display pixel can be enabled with a potentially high sensitivity through properly biasing the TFT into the subthreshold region. We designed, fabricated and characterized the single-pixel TFT followed by the demonstration of a 4 × 4 sensor array along with capturing the first images.