Comprehensive excited state carrier dynamics of 2D selenium: One-photon and multi-photon absorption regimes

Prodhan, S and Chauhan, KK and Singha, T and Karmakar, M and Maity, N and Nadarajan, R and Kumbhakar, P and Tiwary, CS and Singh, AK and Shaijumon, MM and Datta, PK (2023) Comprehensive excited state carrier dynamics of 2D selenium: One-photon and multi-photon absorption regimes. In: Applied Physics Letters, 123 (2).

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Abstract

Semiconductors play a critical role in optoelectronic applications, and recent research has identified group-VI 2D semiconductors as promising materials for this purpose. Here, we report the comprehensive excited state carrier dynamics of bilayer, two-dimensional (2D) selenium (Se) in one-photon and multi-photon absorption regimes using transient reflection (TR) spectroscopy. Carrier lifetime obtained from TR measurement is used to theoretically predict the photo-responsivity for 2D Se photo-detectors operating in the one-photon-absorption regime. We also calculate a giant two-photon absorption cross section of 2.9 × 10 5 GM at 750 nm hinting possible application of 2D Se as a sub-bandgap photo-detector. The carrier recombination process is dominated by surface and sub-surface defect states in one- and multi-photon absorption regimes, respectively, resulting nearly one order increased carrier lifetime in a three-photon-absorption regime (1700 ps) compared to a one-photon-absorption regime (103 ps). Femtosecond Z-scan measurement shows saturation behavior for above bandgap excitation, further indicating the possibility of 2D Se as a saturable absorber material for passive Q-switching. Our study provides comprehensive insight into the excited state carrier dynamics of bilayer 2D Se and highlights its potential as a versatile material for various linear and non-linear optoelectronic applications.

Item Type:	Journal Article
Publication:	Applied Physics Letters
Publisher:	American Institute of Physics Inc.
Additional Information:	The copyright for this article belongs to the Author.
Keywords:	Carrier lifetime; Dynamics; Energy gap; Photodetectors; Photons; Saturable absorbers; Selenium; Semiconductor quantum wells; Surface defects; Two photon processes, Application research; Bi-layer; Carrier dynamics; Excited-states; Multiphoton absorption; One photon absorption; Optoelectronic applications; Photo-detectors; Recent researches; Two-dimensional, Excited states
Department/Centre:	Division of Chemical Sciences > Materials Research Centre
Date Deposited:	04 Aug 2023 08:53
Last Modified:	04 Aug 2023 08:53
URI:	https://eprints.iisc.ac.in/id/eprint/82727

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