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Sensors 2017, 17(8), 1774;

Parametric Optimization of Lateral NIPIN Phototransistors for Flexible Image Sensors

School of Electrical Engineering and Computer Science (EECS), Gwangju Institute of Science and Technology (GIST), 123, Chemdangwagi-ro, Buk-gu, 61005 Gwangju, Korea
These authors contributed equally to this work.
Author to whom correspondence should be addressed.
Received: 29 June 2017 / Revised: 28 July 2017 / Accepted: 29 July 2017 / Published: 2 August 2017
(This article belongs to the Special Issue Flexible Electronics and Sensors)
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Curved image sensors, which are a key component in bio-inspired imaging systems, have been widely studied because they can improve an imaging system in various aspects such as low optical aberrations, small-form, and simple optics configuration. Many methods and materials to realize a curvilinear imager have been proposed to address the drawbacks of conventional imaging/optical systems. However, there have been few theoretical studies in terms of electronics on the use of a lateral photodetector as a flexible image sensor. In this paper, we demonstrate the applicability of a Si-based lateral phototransistor as the pixel of a high-efficiency curved photodetector by conducting various electrical simulations with technology computer aided design (TCAD). The single phototransistor is analyzed with different device parameters: the thickness of the active cell, doping concentration, and structure geometry. This work presents a method to improve the external quantum efficiency (EQE), linear dynamic range (LDR), and mechanical stability of the phototransistor. We also evaluated the dark current in a matrix form of phototransistors to estimate the feasibility of the device as a flexible image sensor. Moreover, we fabricated and demonstrated an array of phototransistors based on our study. The theoretical study and design guidelines of a lateral phototransistor create new opportunities in flexible image sensors. View Full-Text
Keywords: lateral phototransistor; bio-inspired image sensor; curved photodetector array; flexible/stretchable electronics lateral phototransistor; bio-inspired image sensor; curved photodetector array; flexible/stretchable electronics

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Kim, M.S.; Lee, G.J.; Kim, H.M.; Song, Y.M. Parametric Optimization of Lateral NIPIN Phototransistors for Flexible Image Sensors. Sensors 2017, 17, 1774.

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