Equilibrium and Non-Equilibrium Free Carrier Dynamics in 2D Ti₃C₂Tₓ MXenes: THz Spectroscopy Study


MXenes is an emerging class of 2D transition metal carbides, nitrides and carbonitrides which exhibit large conductivity, ultrahigh volumetric capacitance, high threshold for light-induced damage and nonlinear optical transmittance, making them attractive candidates for a variety of optoelectronic and electrochemical applications. Here, we report on equilibrium and non-equilibrium free carrier dynamics of Ti3C2Tx gleaned from THz spectroscopic studies for the first time. Ti3C2Tx showed high (~2 x 1021 cm-3) intrinsic charge carrier density and relatively high (~34 cm2 V-1 s-1) mobility of carriers with an exceptionally large, ~46 000 cm-1 absorption in the THz range, which suggests that Ti3C2Tx is well suited for THz detection. We also demonstrate that Ti3C2Tx conductivity and THz transmission can be manipulated by photoexcitation, as absorption of near-infrared, 800 nm pulses is found to cause transient suppression of the conductivity that recovers over hundreds of picoseconds. The possibility of control over THz transmission and conductivity by photoexcitation suggests the promise for application of Ti3C2Tx Mxenes in THz modulation devices and variable electromagnetic shielding.



Second Department

Materials Science and Engineering

Research Center/Lab(s)

Center for High Performance Computing Research

Keywords and Phrases

carrier dynamics; MXene; terahertz; THz spectroscopy

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Document Type

Article - Journal

Document Version


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Publication Date

01 Jun 2018