High‐Mobility Multilayered MoS₂ Flakes with Low Contact Resistance Grown by Chemical Vapor Deposition

Abstract

The controlled synthesis of high-quality multilayer (ML) MoS flakes with gradually shrinking basal planes by chemical vapor deposition (CVD) is demonstrated. These CVD-grown ML MoS flakes exhibit much higher mobility and current density than mechanically exfoliated ML flakes due to the reduced contact resistance which mainly resulted from direct contact between the lower MoS layers and electrodes.

Stacking-controllable interlayer coupling and symmetric configuration of multilayered MoS2

“…Therefore, the major contribution to VBS is SOC for an odd number of layers, while for an even number of layer, the dominant effect is interlayer interactions. [1][2][3]16,17 However, the structural symmetry in the AA(A…)-stacked multilayers is independent of the even-odd oscillation with the number of layers: all the layers should have broken inversion symmetry, [10][11][12][13] and thus, the observed VBS is mainly contributed by SOC. As shown in Figure 3c, the VBS phenomena exhibited a stacking-orientation dependence, with the AB(A…)-stacked crystal showing larger VBS than the AA(A…)-stacked crystal.…”

“…[10][11][12][13]16,17 Moreover, the remaining stacking order, such as A (BB…) or AA(BA...), with a false order of either AB(A...) or AA(A...) gives rise to a combination of 2H and 3R-phases. Note that these stacking orientations tune the electronic properties by engineering interlayer distances and structural symmetry.…”

“…[3][4][5]11,16,17 To the best of our knowledge, few studies of stacking-orientation-controlled samples of more than three layers and subsequent characterization with PL and Raman spectroscopy have been conducted. [10][11][12][13]18 Furthermore, studying the nonlinear optical properties, such as SHG or four-wave mixing (FWM), as a function of the layer number and stacking orientation of the multi-stacked crystals grown by CVD have scarcely been sought. [4][5][6] The minute variations of the band structures according to the geometry and order of stacking are sufficient to modulate the nonlinear optical susceptibility, and hence, versatile MoS 2 crystals synthesized by CVD play a crucial role in understanding fundamental optoelectronic properties.…”

“…11 In this process, the temperature was identified as a key parameter affecting the growth kinetics of the CVDbased MoS 2 synthesis with a positive correlation between the growth rate and film thickness. [9][10][11][12][13][14] To date, stacking of up to three layers of MoS 2 with various orientations has only been obtained by CVD at high temperatures (⩾850°C). [11][12][13][14] In conventional CVD synthesis, high-order stacking is only possible at high temperatures.…”

Two‐Dimensional Nanomaterials for Photothermal Therapy

“…In CVD methods, the vapor‐phase active precursor reacts or deposits on the surface of the substrate under high temperature and high vacuum conditions to form an ultrathin 2D nanosheets, and the products have large area and excellent electronic properties . A recent study showed that high crystalline multilayer MoS 2 could be produced by a controllable CVD procedure, and the yield can reach to about 70 % . Li et al .…”