Strain-Induced Spatially Resolved Charge Transport in 2H-MoTe₂

Abstract

Strain engineering offers unique control to manipulate the electronic band structure of two-dimensional (2D) materials, resulting in an effective and continuous tuning of the physical properties. Ad hoc straining of 2D materials has demonstrated state of the art photonic devices including efficient photodetectors at telecommunication frequencies, enhancedmobility transistors, and on-chip single photon sources, for example. However, in order to gain insights into the underlying mechanism required to enhance the performance of the next-generation devices with strain(op)tronics, it is imperative to understand the nano-and microscopic properties as a function of a strong nonhomogeneous strain. Here, we study the strain-induced variation of local conductivity of a few-layer transition metal dichalcogenide using conductive atomic force microscopy. We report a strain characterization technique by capturing the electrical conductivity variations induced by local strain originating from surface topography at the nanoscale, which allows overcoming limitations of existing optical spectroscopy techniques. We show that the conductivity variations parallel the strain deviations across the geometry predicted by molecular dynamics simulation. These results substantiate a variation of the effective mass and surface charge density by 0.026m e and 0.03e for every percent of uniaxial strain, respectively, derived using band structure calculation based on the first-principles density functional theory. Furthermore, we demonstrate modulation of the effective Schottky barrier height by quantifying its alteration originating from a gradual reduction of the conduction band minima as a function of tensile strain. Such spatially textured electronic behavior via surface topography-induced strain variations in atomisticlayered materials at the nanoscale opens up exciting opportunities to control fundamental material properties and offers a myriad of design and functional device possibilities, such as for electronics, nanophotonics, flextronics, or smart cloths.

Free-space optical multiplexed orbital angular momentum beam identification system using Fourier optical convolutional layer based on 4f system

“…Both Fourier transform steps are performed entirely passively, overwhelming the electrical time and power consuming convolution. Whats more, in this project, we managed to load two kernels , where achieve parallel convolution via nature diffraction by DMD, [117][118][119][120][121][122][123][124] this property increase the computing throughput to a much higher level. After completion of the Fourier optical convolution and the domain crossing, the signal is electronically post-processed by two fully connected layers with the rectified linear unit (ReLU) activation function to conclude the classification.…”

Mechanical, Elastic, and Adhesive Properties of Two‐Dimensional Materials: From Straining Techniques to State‐of‐the‐Art Local Probe Measurements

“…[126] The effect of the density and energy of surface states on the Schottky barrier at the MoS 2 surface has been also investigated by C-AFM. [127] Notably, Maiti et al [128] used C-AFM to investigate the local conductivity of a few-layer 2H-MoTe 2 , integrated on top of a photonic waveguide (step-like ridge structure). Figure 13a shows the 3D AFM topography of the device, with the 2D material conforming to the underneath structure, with a consequent buildup of tensile strain.…”

“…In this case, the local variations of the maximum of the F el parabola are mapped as a function of location, while scanning the tip on top of the sample surface. A ΔV CPD imaging, to be ultimately [128] Copyright 2021, American Chemical Society. c) evolution from 2D (top) to 1D-like (bottom) Moiré pattern in WSe 2 /MoSe 2 heterobilayers measured by PFM.…”

“…a,b) Reproduced with permission. [ 128 ] Copyright 2021, American Chemical Society. c) evolution from 2D (top) to 1D‐like (bottom) Moiré pattern in WSe 2 /MoSe 2 heterobilayers measured by PFM.…”

“…Inset: schematic of C-AFM. a,b) Reproduced with permission [128]. Copyright 2021, American Chemical Society.…”