Tuning electrical and interfacial thermal properties of bilayer MoS₂ via electrochemical intercalation

Abstract

Layered two-dimensional (2D) materials such as MoS2 have attracted much attention for nano- and opto-electronics. Recently, intercalation (e.g. of ions, atoms, or molecules) has emerged as an effective technique to modulate material properties of such layered 2D films reversibly. We probe both the electrical and thermal properties of Li-intercalated bilayer MoS2 nanosheets by combining electrical measurements and Raman spectroscopy. We demonstrate reversible modulation of carrier density over more than two orders of magnitude (from 0.8 × 1012 to 1.5 × 1014 cm−2), and we simultaneously obtain the thermal boundary conductance between the bilayer and its supporting SiO2 substrate for an intercalated system for the first time. This thermal coupling can be reversibly modulated by nearly a factor of eight, from 14 ± 4.0 MW m−2 K−1 before intercalation to 1.8 ± 0.9 MW m−2 K−1 when the MoS2 is fully lithiated. These results reveal electrochemical intercalation as a reversible tool to modulate and control both electrical and thermal properties of 2D layers.

Energetic and Kinetic Coupling between the Intercalated Atom and Intrinsic S Vacancy in the MoS2 Bilayer

“…It has been shown that a pressure as large as 20 GPa is needed to motivate the phase transition from 2H to 2Ha. 51−53 According to the experiment, the 2H-1T phase transition can be induced when the Li intercalation concentration is around 11.8% (Li 0.4 MoS 2 ), 54 which perfectly matches the theoretical calculation, 55 while for the low intercalation concentration of 1% (LiMo 32 S 64 , as used in our simulation), no feature of phase transition from 2H to 2Ha or 1T has been reported in the experiments so far. Thus, in practice, the 2H-2Ha phase transition can be prohibited by the kinetic barrier for our systems, and so here we focus on the 2H phase, and the most stable inserting site for the guest atoms is the regular octahedral site.…”

Impact of Large Gate Voltages and Ultrathin Polymer Electrolytes on Carrier Density in Electric-Double-Layer-Gated Two-Dimensional Crystal Transistors

“…Included in this category are electric-double-layer transistors (EDLTs), which are FETs in which the gate oxide is replaced by an electrically insulating but ionically conductive electrolyte. While such a device could also undergo electrochemical reaction under sufficiently large gate voltage, ,− in this study we consider EDLTs as ionically gated FETs for which electrochemical reactions are absent. As Leighton et al.…”