Multiple-Dimensionally Controllable Nucleation Sites of Two-Dimensional WS₂/Bi₂Se₃ Heterojunctions Based on Vapor Growth

Abstract

Two-dimensional (2D) heterojunctions have attracted great attention due to their excellent optoelectronic properties. Until now, precisely controlling the nucleation density and stacking area of 2D heterojunctions has been of critical importance but still a huge challenge. It hampers the progress of controlled growth of 2D heterojunctions for optoelectronic devices because the potential relation between numerous growth parameters and nucleation density is always poorly understood. Herein, by cooperatively controlling three parameters (substrate temperature, gas flow rate, and precursor concentration) in modified vapor deposition growth, the nucleation density and stacking area of WS 2 /Bi 2 Se 3 vertical heterojunctions were successfully modulated. High-quality WS 2 /Bi 2 Se 3 vertical heterojunctions with various stacking areas were effectively grown from single and multiple nucleation sites. Moreover, the potential nucleation mechanism and efficient charge transfer of WS 2 /Bi 2 Se 3 vertical heterojunctions were systematically studied by utilizing the density functional theory and photoluminescence spectra. This modified vapor deposition strategy and the proposed mechanism are helpful in controlling the nucleation density and stacking area of other heterojunctions, which plays a key role in the preparation of electronic and optoelectronic nanodevices.

Interlayer Exciton–Phonon Bound State in Bi2Se3/Monolayer WS2 van der Waals Heterostructures

“…19 We note that the adjacent Bi 2 Se 3 dramatically reduces the PL intensity of the WS 2 , due in part to the emergence of nonradiative recombination pathways and charge transfer from the monolayer WS 2 into Bi 2 Se 3 . 17,18 We also observe a strong reduction (>2×) in PL intensity. But in addition, our work clearly reveals the presence of these exciton−phonon bound state interactions.…”

“…Previous work found notable interlayer hybridization between Bi 2 Se 3 and monolayer WS 2 that greatly impacts the WS 2 excitonic activity, 17,18 strains atoms at the interface, 16 and induces the formation of a pure electronic moirélattice at the interface. 16 Such interlayer hybridization facilitates the exchange of electrons between the materials and modifies interlayer bonding, thereby setting conditions that encourage the formation of interlayer quasiparticles.…”

Room-Temperature Oxygen Transport in Nanothin BixOySez Enables Precision Modulation of 2D Materials

“…Figure d is a fluorescence image showing the PL intensity contrast between monolayer WSe 2 and a Bi 2 Se 3 -WSe 2 2D heterostructure. While monolayer WSe 2 exhibits the expected bright PL, a single layer of Bi 2 Se 3 quenches the PL nearly completely, behavior that has been observed in other Bi 2 Se 3 -TMD 2D heterostructures. ,, Previous work suggests that the strong interlayer coupling in Bi 2 Se 3 -TMD 2D heterostructures induces the formation of a pure electronic lattice at the interface, encouraging hybridization and nonradiative excitonic transitions …”

“…While monolayer WSe 2 exhibits the expected bright PL, a single layer of Bi 2 Se 3 quenches the PL nearly completely, behavior that has been observed in other Bi 2 Se 3 -TMD 2D heterostructures. 33,34,37 Previous work suggests that the strong interlayer coupling in Bi 2 Se 3 -TMD 2D heterostructures induces the formation of a pure electronic lattice at the interface, encouraging hybridization and nonradiative excitonic transitions. 38 Figure 6 demonstrates that the initial laser−oxygen exposure that induces transformation into Bi x O y Se z transformation also restores the WSe 2 PL.…”

2D Bi2Se3 materials for optoelectronics

“…Except individual Bi 2 Se 3 , the heterostructures based on 2D Bi 2 Se 3 were also demonstrated in the application of photodetection ( She et al., 2021 ; Zhang et al., 2016 , 2019 , 2020 ). Zhai et al.…”