Study of current-mode active pixel sensor circuits using amorphous InSnZnO thin-film transistor for 50-μm pixel-pitch indirect X-ray imagers. (May 2017)

• Record Type: Journal Article
• Authors: Cheng, Mao-Hsun; Zhao, Chumin; Kanicki, Jerzy
• Is Part Of: Solid-state electronics. Volume 131(2017)
• Page Start: 53
• Page End: 64
• Publication Date: 2017-05
• Subjects: Active pixel sensor -- Amorphous indium-tin-zinc oxide thin-film transistor -- Current mode -- Imager -- Photodiode; Semiconductors -- Periodicals; Semiconducteurs -- Périodiques; 621.38152
• DOI: 10.1016/j.sse.2017.02.006
• Languages: English
• ISSNs: 0038-1101

Abstract

Abstract: Current-mode active pixel sensor (C-APS) circuits based on amorphous indium-tin-zinc-oxide thin-film transistors (a-ITZO TFTs) are proposed for indirect X-ray imagers. The proposed C-APS circuits include a combination of a hydrogenated amorphous silicon (a-Si:H) p + -i-n + photodiode (PD) and a-ITZO TFTs. Source-output (SO) and drain-output (DO) C-APS are investigated and compared. Acceptable signal linearity and high gains are realized for SO C-APS. APS circuit characteristics including voltage gain, charge gain, signal linearity, charge-to-current conversion gain, electron-to-voltage conversion gain are evaluated. The impact of the a-ITZO TFT threshold voltage shifts on C-APS is also considered. A layout for a pixel pitch of 50 μm and an associated fabrication process are suggested. Data line loadings for 4k-resolution X-ray imagers are computed and their impact on circuit performances is taken into consideration. Noise analysis is performed, showing a total input-referred noise of 239 e − .