Edge induced band bending in van der Waals heterojunctions: A first principle study

Abstract

The dangling bond free nature of two-dimensional (2D) material surface/interface makes van der Waals (vdW) heterostructure attractive for novel electronic and optoelectronic applications. But in practice, edge is unavoidable and could cause band bending at 2D material edge analog to surface/interface band bending in conventional three-dimensional (3D) materials. Here, we report a first principle simulation on edge band bending of free standing MoS 2 /WS 2 vdW heterojunction. Due to the imbalance charges at edge, S terminated edge causes upward band bending while Mo/W terminated induces downward bending in undoped case. The edge band bending is comparable to band gap and could obviously harm electronic and optoelectronic properties. We also investigate the edge band bending of electrostatic doped heterojunction. N doping raises the edge band whereas p doping causes a decline of edge band. Heavy n doping even reverses the downward edge band bending at Mo/W terminated edge. In contrast, heavy p doping doesn't invert the upward bending to downward. Comparing with former experiments, the expected band gap narrowing introduced by interlayer potential gradient at edge is not observed in our free-standing structures and suggests substrate's important role in this imbalance charge induced phenomenon.

Phase control and lateral heterostructures of MoTe2 epitaxially grown on graphene/Ir(111)

“…Similar band bending effects have been reported in other semiconducting TMDs in both lateral and vertical heterojunctions, [50][51][52] in the vicinity of MTBs and structural defects [53][54][55] and at the edges of the material. 56,57 3.3.2 1H/MTB interface.…”

Transition metal dichalcogenide-based mixed-dimensional heterostructures for visible-light-driven photocatalysis: Dimensionality and interface engineering

“…Because of non-passivated edge states (imbalance charges), the energy band structure of 2D-2D heterostructures would change at the edges. This is similar to surface/interface band bending in conventional 3D materials [184]. For example, in MoS2-WS2 vdW heterostructures, N-doping raises the edge band, whereas P-doping leads to a decline of the edge band [184].…”

“…This is similar to surface/interface band bending in conventional 3D materials [184]. For example, in MoS2-WS2 vdW heterostructures, N-doping raises the edge band, whereas P-doping leads to a decline of the edge band [184].…”

Observation of the photovoltaic effect in a van der Waals heterostructure

“…The photocurrent on both edges probably arises from the band bending at the lateral interface between MoS 2 and WS 2 / MoS 2 . 23 The orbital hybridization between WS 2 and MoS 2 changes the electronic bands of MoS 2 only in the WS 2 /MoS 2 region, resulting in band bending at the interface. Similar photocurrent signals were also observed in other heterostructures, such as graphene/MoS 2 24 (Fig.…”