High performance amorphous metal-oxide semiconductors thin-film passive and active pixel sensors

Abstract

In this paper, for the first time, we report on high performance amorphous In-Ga-Zn-O (a-IGZO) thin-film transistors (TFTs) based passive pixel sensor (PPS) and active pixel sensor (APS) circuits. Experimental results show that single-TFT PPS with a pitch length of 50μm can achieve a signal charge gain approaching to unity (Gain=0.93) under a fast readout time of 20μs and a dynamic range of 40dB. APS based on three a-IGZO TFTs, with a pitch length of ∼100μm, established a high dynamic range of more than 60dB. 2-TFTs half active pixel sensor (H-APS) testing circuits are also designed to investigate the voltage gain (A <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V</inf> =Δ <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">VOUT</inf> /ΔV <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">G</inf> ) properties for the APS circuit in this work. For the a-IGZO APS, A <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V</inf> is measured to be ∼1.25, and through normalization of the pixel capacitance (C <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">PIX</inf> ) to a common value of 5pF, a large signal charge gain of 25 is obtained.