Toward GHz Bandwidths with WSe2 Photodetectors
2023-12-18

Toward GHz Bandwidths with WSe2 PhotodetectorsFabian Strauss a, Marcus Scheele aa University of Tuebingen, Germany, Auf der Morgenstelle, 18, Tübingen, GermanyMaterials for Sustainable Development Conference (MATSUS)Proceedings of MATSUS Spring 2024 Conference (MATSUS24)#NextGenPD - Next Generation Photo-and-radiation detectorsBarcelona, Spain, 2024 March 4th - 8thOrganizers: Ardalan Armin and Nicola GaspariniOral, Marcus Scheele, presentation 034DOI: https://doi.org/10.29363/nanoge.matsus.2024.034Publication date: 18th December 2023Photodetectors on the basis of transition metal dichalcogenides (TMDCs) have let to impressive performance numbers with regard to gain and responsivity.1 In contrast, their speed, parametrized by the response time and 3dB electrical bandwidth, has been mostly disappointing so far with response times often ranging in the milli- to microsecond regimes. The corresponding 3dB bandwidths seldomly exceed a few MHz, and this is too slow to be competitive with established, fast photodetection materials that typically operate with GHz speed. This presentation details how rational tuning of the substrate material,2 the contact geometry,3 the photoresistance and the capacitance4 of lateral photodetectors based on mechanically exfoliated WSe2 layers affects the 3dB bandwidth and enables photodetection with a speed in excess of 230 MHz. We show that optical switching with such devices can be carried out at zero bias, requiring just 27 fJ per switching event. Reducing the detector thickness to mono- and bilayers of WSe2 only weakly decreases the response speed, rendering WSe2 advantageous over MoS2 for fast optical communication. Further miniaturizations of the device geometry have the potential for Gigahertz photodetection with such easily fabricated TMDC photodetectors which exhibit long-term stability under ambient conditions. References:[1] Huo, N.; Konstantatos, G. Recent Progress and Future Prospects of 2D-Based Photodetectors. Adv. Mat. 2018, 30, 1801164.[2] Schedel, C.; Strauß, F.; Kohlschreiber, P.; Geladari, O.; Meixner, A. J.; Scheele, M. Substrate Effects on the Speed Limiting Factor of WSe2 Photodetectors. Phys. Chem. Chem. Phys. 2022, 24, 25383 - 25390.[3] Strauß, F.; Schedel, C.; Scheele, M. Edge Contacts accelerate the Response of MoS2 Photodetectors. Nanoscale Advances 2023, 5, 3494 - 3499.[4] Strauß, F.*; Kohlschreiber, P.*; Keck, J.; Michel, P.; Hiller, J.; Meixner, A. J.; Scheele, M. A simple 230 MHz Photodetector Based on Exfoliated WSe2 Multilayers. ChemRxiv Preprint 2023.© FUNDACIO DE LA COMUNITAT VALENCIANA SCITOnanoGe is a prestigious brand of successful science conferences that are developed along the year in different areas of the world since 2009. 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