Hydrogen-assisted post-growth substitution of tellurium into molybdenum disulfide monolayers with tunable compositions

Abstract

Herein we report the successful doping of tellurium (Te) into molybdenum disulfide (MoS) monolayers to form MoS Te alloy with variable compositions via a hydrogen-assisted post-growth chemical vapor deposition process. It is confirmed that H plays an indispensable role in the Te substitution into as-grown MoS monolayers. Atomic-resolution transmission electron microscopy allows us to determine the lattice sites and the concentration of introduced Te atoms. At a relatively low concentration, tellurium is only substituted in the sulfur sublattice to form monolayer MoSTe alloy, while with increasing Te concentration (up to ∼27.6% achieved in this study), local regions with enriched tellurium, large structural distortions, and obvious sulfur deficiency are observed. Statistical analysis of the Te distribution indicates the random substitution. Density functional theory calculations are used to investigate the stability of the alloy structures and their electronic properties. Comparison with experimental results indicate that the samples are unstrained and the Te atoms are predominantly substituted in the top S sublattice. Importantly, such ultimately thin Janus structure of MoSTe exhibits properties that are distinct from their constituents. We believe our results will inspire further exploration of the versatile properties of asymmetric 2D TMD alloys.

Efficient method for calculating Raman spectra of solids with impurities and alloys and its application to two-dimensional transition metal dichalcogenides

“…Again, lighter impurities lead to additional peaks at higher frequencies and heavier impurities at lower frequencies, but the features that are most likely to be observed in experiments are those falling above the A 2 mode or inside the gap between E mode and the LA(M) edge. In fact, such features have been reported in the literature for MoS 2 with light Se alloying at about 270 cm −1 [9,10,31,68] and with light Te alloying at about 243 cm −1 [69], agreeing well with our calculations.…”

Geometry and Greatly Enhanced Thermoelectric Performance of Monolayer MXY Transition‐Metal Dichalcogenide: MoSTe as an Example

“…Regarding the possible synthesis of the most stable blend structure, we can get inspiration from the reported synthesis work of random MoS 2Àx Te x alloys in previous studies. [76][77][78][79][80][81] For example, Yun et al synthesized monolayer MoS 2 on SiO 2 /Si wafers by chemical vapor deposition (CVD) at first, and then transferred MoS 2 to a NaOH-coated substrate on a ceramic crucible. Finally, two-zone CVD was introduced to achieve the tellurization process.…”

Heterogeneous Electronic and Photonic Devices Based on Monolayer Ternary Telluride Core/Shell Structures

“…In contrast, chemical vapor deposition (CVD) synthesis provides much better control on the crystal thickness and is more promising for large‐scale production. Recently, it was reported that tellurium alloys can be synthesized using CVD as well, including hydrogen‐assisted post‐growth substitution of tellurium into MoS 2 , [ 29 ] growing MoSe 2(1− x ) Te 2 x alloys using sodium cholate, [ 30 ] tellurizing MoS 2 and WS 2 via alkali metal scooter, [ 28 ] and synthesizing WTe 2 S 2(1− x ) using sodium chloride. [ 31 ] However, the ternary telluride heterostructures and their electronic and photonic devices remain unexplored.…”