Effects of dielectric screening on the excitonic and critical points properties of WS₂/MoS₂ heterostructures

Abstract

Vertical van der Waals heterostructures have aroused great attention, owing to their promising application in next generation nanoelectronic and optoelectronic devices. The dielectric screening effect plays a key role on...

Phonon and Exciton Properties between WS2 and MoS2 Layers via Inversion Heterostructure Engineering

“…However, the position of four peaks shifts slightly due to dielectric screening in vdWHs. 20,24 The A(MoS 2 ), A − (WS 2 ), A(WS 2 ), and B(MoS 2 ) in 1LW/1LM and 1LM/1LW vdWHs under 532 nm excitation shown in Figure S2a are consistent with the above results. We further presented calculational electronic bands of vdWH with 1LW and 1LM superimposed with each other by density-functional theory (DFT), and the results confirm the existence of interlayer coupling in 1LW and 1LM, as shown in Figure S4 of the Supporting Information.…”

“…38,39 The blue shift of A 1g is due to increasing restoring forces, as additional layers and the interlayer van der Waals forces are added to suppress atom vibration. 35,40 In 1LW/1LM vdWH, the E 24 It is more reasonable that the effective dielectric screening induces the softening of E 1 2g (WS 2 ) and E 1 2g (MoS 2 ) modes in our vdWHs. However, the softening of A 1g (MoS 2 ) in vdWHs can be ascribed to increasing restoring forces 35 less than that of electron doping 16,20 due to the electron transfer from 1LW to 1LM.…”

“…22,23 Recently, effects of dielectric screening on the excitonic and critical points properties of WS 2 /MoS 2 heterostructures have been reported. 24 The interlayer and extra-layer dielectric screening make vdWHs composed of WS 2 and MoS 2 sensitive to the surrounding environment, and the influence on phonons and excitons in vdWHs with WS 2 and MoS 2 remains largely unexplored. In this paper, we systematically studied WS 2 /MoS 2 vdWH with WS 2 flake on top of MoS 2 flake and MoS 2 /WS 2 vdWH composed of MoS 2 flake on top of WS 2 flake on the bottom using Raman spectroscopy and PL spectroscopy.…”

“…The vdWHs composed of WS 2 and MoS 2 are such excellent structures to study phonon and exciton coupling because type-II band alignment, which facilitates the electron/hole transfer more efficiently or even dominated, is usually formed between these vdWHs. , Studies on vdWHs with WS 2 and MoS 2 are mainly reflected in interlayer interface couplings, , interlayer twisted angles, − interlayer phonons, interlayer excitons, , and charge transfer at the interface. , Recently, effects of dielectric screening on the excitonic and critical points properties of WS 2 /MoS 2 heterostructures have been reported . The interlayer and extra-layer dielectric screening make vdWHs composed of WS 2 and MoS 2 sensitive to the surrounding environment, and the influence on phonons and excitons in vdWHs with WS 2 and MoS 2 remains largely unexplored.…”

Interlayer Excitons in Transition Metal Dichalcogenide Semiconductors for 2D Optoelectronics

“…[78] These pioneering proofofconcept devices form the basis for probing the interlayer excitons in future 2D hetero structured optoelectronic applications. MoS 2 220 ± 10, [56] 240, [24] 253, [46] 570 [57] WSe 2 /MoS 2 K-K: 280, [58] 290, [59] 310; [60] K-Γ: 260, [61] 550 [59] MoSe 2 550 [51] MoSe 2 /WSe 2 200, [62] 246, [63] 260 [64] WS 2 320 ± 40, [45] 550, [49] 700 [65,66] WS 2 /MoS 2 431.39 ± 127.818 [67] WSe 2 370, [47] 440, [49] 600 ± 200 [50] WSe 2 /WS 2 126 ± 7 [68] MoTe 2 185 [69] MoSe 2 /MoS 2 90 [70]…”