Investigation and optimization of light trapping through hexagonal-shaped nanopillar (NP) array of indium gallium arseni
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Investigation and optimization of light trapping through hexagonal‑shaped nanopillar (NP) array of indium gallium arsenide material based photodetector Smriti Baruah1 · Joyatri Bora1 · Santanu Maity2 Received: 13 May 2020 / Accepted: 28 July 2020 © Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract Nanopillar arrays over the photodetector’s surface attribute an enhanced coupling efficiency of incident light due to its various light trapping mechanisms that contribute towards high-resolution optical detection. This paper reports the analytical investigation of the performance of Indium Gallium Arsenide material based hexagonal-shaped nanopillar (NP) array deployed over the 5 um × 5 um detector’s front surface for high photodetection infrared applications. The proposed structure exhibits an optimum 98% overall absorption of the incoming light. High EQE of about 75% and responsivity of 0.93 A/W has been obtained at 1.55 um operating wavelength with a minimum detector’s depletion width of 0.7 um at 1 mw optical input power. Keywords Photodetector · Nanopillar · Multiple reflections · Absorption · Quantum efficiency · Responsivity
1 Introduction Photodetectors in recent years have been widely explored as a multispectral detection device in the field of sensing and imaging applications including medical diagnostics and industrial systems (Zhao et al. 2017). In this respect photodetectors, based on ternary band gap indium gallium arsenide (InGaAs) materials have emerged as a most prominent candidate for its application in short wavelength infrared sensing and also as the workhorse of optical communication by currently achieving a data communication rate as high as 2.5 Gbits/s (Karol 2019). However, they must have an extremely fast response and should exhibit high reliability at a lower cost (De Iacovo et al. 2016). Inefficient coupling of light in the detector’s surface due to high air semiconductor refractive mismatch severely limits the photodetector performance (Ackert et al. 2015). Therefore, reduction in reflection losses has always attracted researchers as it by far is * Smriti Baruah [email protected] 1
North Eastern Regional Institute of Science and Technology, Nirjuli, India
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IIEST Shibpur, Howrah, India
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the most important criterion needed for achieving highly efficient photodetectors (Schubert et al. 2010). Conventional antireflection coatings (ARC) consists of thin films of dielectric materials which are coated on the optical substrate for reducing reflection losses caused by a sudden change of refractive index change operates within a narrow wavelength range and for small variations of incident angles (Keshavarz Hedayati and Elbahri 2016; Sanatinia et al. 2012). Also due to the unavailability of the precise desired refractive index of the thin film materials, optimum reduction of light reflection losses is not achievable in a practical sense. In order to remove all these physical and structural constrain
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