New Amorphous In–Ga–Zn–O Thin-Film Transistor-Based Optical Pixel Sensor for Optical Input Signal With Short Wavelength

This paper presents an optical sensor based on amorphous In-Ga-Zn-O (a-IGZO) photo thin-film transistors (TFTs). To maintain a high signal-to-noise ratio (SNR) of the optical sensor against a variety of ambient white light, this paper employed a-IGZO photo-TFTs for detecting optical input signal sensitive only to short-wavelength light. Measurements of the photosensitivity for optical signal with different wavelengths and optical response for optical input signal under various white light irradiances are proposed to support the reliability of the a-IGZO photo-TFTs under different ambient white light conditions. This paper also simulates a-IGZO photo-TFTs under various white light conditions to predict and design the proposed new sensors and circuits. The simulation results indicated that the proposed optical sensor can maintain the obvious difference in the output voltages with or without optical input signal under the white light irradiances of 0, 268 and 750 μW/cm
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, demonstrating the feasibility and the reliability of the proposed optical pixel sensor.