Structural optimization and analysis of GaAs buried-gate OPFET for visible-light communication
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Structural optimization and analysis of GaAs buried‑gate OPFET for visible‑light communication Jaya V. Gaitonde1 · Rajesh B. Lohani1 Received: 15 April 2019 / Accepted: 3 November 2020 / Published online: 17 November 2020 © Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract Opto-Electronic Integrated Circuit (OEIC) receivers offer greater advantages over other discrete devices in Visible Light Communication (VLC). Use of Optical Field-Effect Transistor (OPFET) as a photodetector-cum-amplifier has been amply identified for VLC and other related applications. OPFET offers simultaneous high sensitivity, large bandwidth, and high unity-gain cut-off frequency in relation to other state-of-art p-i-n and avalanche photodiodes (APDs). OPFET also has the additional advantage of the ability to operate at lower voltages than photodiodes. In this paper, we carry out the structural optimization of medium- and long-channel GaAs buried-gate OPFET for 600 nm wavelength operation with an in-depth analysis based on the photoconductive and photovoltaic effects, the scaling rules-induced effects, and the channel length variation effects. The bandwidth and the unity-gain cut-off frequency (fT) are simultaneously optimized with a responsivity greater than 2 × 105 A/W as a constraint. The optimization with and without any constraint on the dark current is discussed. Simulation results demonstrate that it is possible to achieve simultaneous detection and amplification up to modulation frequencies of 1.9 GHz and 3.6 GHz at radiation flux densities of 1 016 and 1019 /m2-s. Corresponding responsivities of 108 and 1 06 A/W or higher are also achievable surpassing what is achievable in photodiodes. Simulation results are in line with previously published experimental results. The study results hold out the promise of a better potential use of OPFET for high data rate VLC applications. Remarkably, the manuscript establishes and explains for the first time the direct relationship of the 3-dB bandwidth with gate length. Keywords Visible-light communication (VLC) · Optical field effect transistor (OPFET) · Buried-gate · Optimization · Opto-electronic integrated circuits (OEICs)
* Jaya V. Gaitonde [email protected] Rajesh B. Lohani [email protected] 1
Electronics and Telecommunication Department, Goa Engineering College (Goa University), Farmagudi, Ponda, Goa 403401, India
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J. V. Gaitonde, R. B. Lohani
1 Introduction Visible-Light Communication (VLC) has gained tremendous importance in recent years as a promising alternative to RF-based communication. With the growing demand for higher communication bandwidth, the RF with its narrow bandwidth is insufficient to cater to the requirements. With a spectrum range of 385 THz to 800 THz, VLC’s bandwidth is a thousand times larger than the RF spectrum. The important benefits of VLC are cost efficiency, energy efficiency, and unregulated large bandwidth (Ergul et al. 2015). Its potential applications include Li-Fi (
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