The Opposite Anisotropic Piezoresistive Effect of ReS₂

Abstract

Mechanical strain induced changes in the electronic properties of two-dimensional (2D) materials is of great interest for both fundamental studies and practical applications. The anisotropic 2D materials may further exhibit different electronic changes when the strain is applied along different crystalline axes. The resulting anisotropic piezoresistive phenomenon not only reveals distinct lattice–electron interaction along different principle axes in low-dimensional materials but also can accurately sense/recognize multidimensional strain signals for the development of strain sensors, electronic skin, human–machine interfaces, etc. In this work, we systematically studied the piezoresistive effect of an anisotropic 2D material of rhenium disulfide (ReS2), which has large anisotropic ratio. The measurement of ReS2 piezoresistance was experimentally performed on the devices fabricated on a flexible substrate with electrical channels made along the two principle axes, which were identified noninvasively by the reflectance difference microscopy developed in our lab. The result indicated that ReS2 had completely opposite (positive and negative) piezoresistance along two principle axes, which differed from any previously reported anisotropic piezoresistive effect in other 2D materials. We attributed the opposite anisotropic piezoresistive effect of ReS2 to the strain-induced broadening and narrowing of the bandgap along two principle axes, respectively, which was demonstrated by both reflectance difference spectroscopy and theoretical calculations.

Strain‐Engineered Anisotropic Optical and Electrical Properties in 2D Chiral‐Chain Tellurium

“…Lattice structure and crystal symmetry dictate a 2D semiconductor's properties and their interaction with the external stimuli. [ 28,29,2,30,31 ] Many 2D materials with reduced symmetry (e.g., BP, [ 32 ] ReS 2 , [ 28 ] Ta 2 NiS 5 , [ 33 ] etc.) show strong in‐plane anisotropy, leading to significant differences in property change and material response when the strain is applied along different in‐plane crystalline directions.…”

“…show strong in‐plane anisotropy, leading to significant differences in property change and material response when the strain is applied along different in‐plane crystalline directions. [ 28,29,34,2,31 ] Exploration of the anisotropic strain response and properties in 2D materials has both scientific (e.g., anisotropic plasmons, linear dichroism, etc.) [ 35,36 ] and technologic significance (e.g., polarization‐sensitive detectors, [ 37,38,36,39 ] polarized imaging devices, [ 40,29 ] and high‐performance multiaxial strain sensors).…”

Modulation of the Anisotropic Electronic Properties in ReS 2 via Ferroelectric Film

“…As the polarization voltage increases from 0 to −10 V, the ratio changes significantly from ∼0.70 to ∼4.01, which is strong evidence of the remarkable ability of ferroelectric P(VDF-TrFE) film on the modulation anisotropic electronic properties of 2-D materials. According to reported studies 45 , strain (that might be induced by ferroelectric coating film) can also contribute to the change of electric conductivity. To verify the dominant role of ferroelectric polarization in our case, we made a rough estimation on this issue as explained below (also see Supporting Information Figure S5).…”

Two‐dimensional materials: From mechanical properties to flexible mechanical sensors

“…A, Schematic of flexible mechanical sensor based on 2D materials and flexible substrate. Reproduced with permission . Copyright 2019, American Chemical Society.…”