Concentration Phase Separation of Substitution‐Doped Atoms in TMDCs Monolayer

Abstract

The density and spatial distribution of substituted dopants affect the transition metal dichalcogenides (TMDCs) materials properties. Previous studies have demonstrated that the density of dopants in TMDCs increases with the amount of doping, and the phenomenon of doping concentration difference between the nucleation center and the edge is observed, but the spatial distribution law of doping atoms has not been carefully studied. Here, it is demonstrated that the spatial distribution of dopants changes at high doping concentrations. The spontaneous formation of an interface with a steep doping concentration change is named concentration phase separation (CPS). The difference in the spatial distribution of dopants on both sides of the interface can be identified by an optical microscope. This is consistent with the results of spectral analysis and microstructure characterization of scanning transmission electron microscope. According to the calculation results of density functional theory, the chemical potential has two relatively stable energies as the doping concentration increases, which leads to the spontaneous formation of CPS. Understanding the abnormal phenomena is important for the design of TMDCs devices. This work has great significance in the establishment and improvement of the doping theory and the design of the doping process for 2D materials.

Structural Instability Stimulated Heteroatoms Co‐Doping of 2D Quaternary Semiconductor for Optoelectronic Applications

“…This alteration served as the primary driving force behind the tensile strain observed in the 2D alloy, ultimately leading to a blue shift in the phonon modes associated with MoS 2 , as shown in Figure 2i,j. [ 30,31 ] In addition, the introduction of oxygen atoms can also lead to changes in MoS 2 , causing a blue shift in the A 1g mode. [ 27 ]…”

Spin-Stabilization by Coulomb Blockade in a Vanadium Dimer in WSe2

“…These fluctuations can occur within a relatively abrupt transition region of a few nanometers. 17 We take advantage of this naturally occurring inhomogeneity of the dopant distribution to study isolated single V impurities and V dimers of different spacing. In Figure 1a−d STM topographies of V-doped WSe 2 with different local V concentrations are shown.…”

“…Using STM, we observe substantial variations of the local V density ranging from 0.15% to 4% (see Figure S1) in several samples. These fluctuations can occur within a relatively abrupt transition region of a few nanometers . We take advantage of this naturally occurring inhomogeneity of the dopant distribution to study isolated single V impurities and V dimers of different spacing.…”

Advance in twisted transition metal dichalcogenides: synthesis, characterization, and properties

“…Since the physical properties of t-TMDCs largely depend on the quality and integrity of its structure, obtaining high-quality monolayer t-TMDCs from the original material is crucial. Any defects [23] or doping [24] can potentially impact the final performance of the t-TMDCs. During the stacking, the crystal orientation is a key factor.…”