Single Layer Molybdenum Disulfide under Direct Out-of-Plane Compression: Low-Stress Band-Gap Engineering

Abstract

Tuning the electronic structure of 2D materials is a very powerful asset toward tailoring their properties to suit the demands of future applications in optoelectronics. Strain engineering is one of the most promising methods in this regard. We demonstrate that even very small out-of-plane axial compression readily modifies the electronic structure of monolayer MoS2. As we show through in situ resonant and nonresonant Raman spectroscopy and photoluminescence measurements combined with theoretical calculations, the transition from direct to indirect band gap semiconductor takes place at ∼0.5 GPa, and the transition to a semimetal occurs at stress smaller than 3 GPa.

Single photon emission from deep-level defects in monolayerWSe2

“…The PC of X 0 peak reflects a blue-shift rate of band edge of the direct K-K interband transition. [18][19][20][21] Here, the PC of X 0 at low temperature is nearly a half of the value for 2D-X 0 at room temperature reported elsewhere. 22 The discrepancy in the PC values obtained at different temperatures is at moment not understood.…”

Ionic strength induced electrodeposition of two-dimensional layered MoS 2 nanosheets

“…Therefore, the observed blue-shift of E 1 2g peak for electrodeposited layered MoS 2 nanosheets in comparison to bulk MoS 2 is consistent with the literature [5][6][7][8]32]. On the contrary, blue-shift in A 1g peak may result from the strain experienced during the PAA-MoS 2 formation and/or stacking-induced electrodeposition process, which probably causes the surface reconstruction where weak interlayer interaction in MoS 2 can affect the intralayer bonding as well as lattice dynamics [32,33]. Moreover, it has been also shown that the frequency difference ( ) of two characteristic Raman modes increases with the thickness, which can be used to identify the MoS 2 layer number [8,32,[34][35][36].…”

A tight-binding model for MoS2monolayers

“…Therefore, the conductance band can be obtained from α 0 − θ L variables, while the valence band comes from the α L2 − θ R combinations, resulting in the expressions E conductance (K) = ∆ 0 +V E 00 + ∆ p +U E 11 + s 11 Following the same procedure for other blocks, we find analytical expressions for nearly all energies at the K point. Thus, each block corresponds to a majority orbital composition and each eigenvalue (two for each block 2 × 2) is matched to a DFT-HSE06 value.…”