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Two-dimensional sensor array for low-level light detection

Chang, JH; Vygranenko, Y; Nathan, A; (2004) Two-dimensional sensor array for low-level light detection. In: Proceedings of SPIE. (pp. 420 - 427). SPIE - The International Society for Optical Engineering: Bellingham, US.

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Abstract

This paper presents the design, fabrication process, and performance evaluation of a two-dimensional hydrogenated amorphous silicon (a-Si:H) n-i-p photodiode array, developed specifically for low-level light sensor applications. The design of the device is simpler than conventional active-matrix-arrays with thin-film transistor (TFT) addressing electronics, owing to the utilization of the a-Si:H switching diodes for signal readout. Since both sensor diodes and switching diodes are formed simultaneously through dry etching the entire wafer area, the mask count required for lithography is reduced to six. The most challenging problem associated with the fabrication of these devices is the excess leakage current, which inherently limits the output signal-to-noise ratio and dynamic range. The reverse dark current in the photodiodes were minimized by tailoring the defects at the i-p interface. The junction-edge leakage current in the switching diodes is associated with damage caused by ion bombardment, and can be reduced by optimizing of the plasma processing conditions. A 3×4 pixels array prototype was tested using a specially designed test board which performs pre-amplification, double sampling and final amplification for each column of the array. Details of the signal readout process along with detector performances are presented and discussed.

Type:Proceedings paper
Title:Two-dimensional sensor array for low-level light detection
DOI:10.1117/12.567181
Publisher version:http://dx.doi.org/10.1117/12.567181
Additional information:Photonics North 2004: Photonic Applications in Astronomy, Biomedicine, Imaging, Materials Processing, and Education took place in Ottawa, Canada between 26-29 September 2004
UCL classification:UCL > School of BEAMS > Faculty of Maths and Physical Sciences > London Centre for Nanotechnology

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