Vertical Heterostructure of Two-Dimensional MoS₂ and WSe₂ with Vertically Aligned Layers

TLDR

Two‑dimensional layered materials are covalently bonded sheets held together by van der Waals forces, giving rise to orientation‑dependent properties and enabling novel device geometries with potential electronic and optoelectronic applications. The study aims to synthesize a vertical heterostructure of n‑type MoS₂ and p‑type WSe₂ with vertically aligned atomic layers. The vertical heterostructure is fabricated by vertically aligning n‑type MoS₂ and p‑type WSe₂ layers into a nanofilm. The vertically aligned MoS₂/WSe₂ heterostructure was successfully synthesized without alloying, scaled to over 1 cm², and exhibited pn‑junction diode behavior.

Abstract

Two-dimensional (2D) layered materials consist of covalently bonded 2D atomic layers stacked by van der Waals interactions. Such anisotropic bonding nature gives rise to the orientation-dependent functionalities of the 2D layered materials. Different from most studies of 2D materials with their atomic layers parallel to substrate, we have recently developed layer vertically aligned 2D material nanofilms. Built on these developments, here, we demonstrate the synthesis of vertical heterostructure of n-type MoS2 and p-type WSe2 with vertically aligned atomic layers. Thin film of MoS2/WSe2 vertical structure was successfully synthesized without significant alloy formation. The heterostructure synthesis is scalable to a large area over 1 cm2. We demonstrated the pn junction diode behavior of the heterostructure device. This novel device geometry opens up exciting opportunities for a variety of electronic and optoelectronic devices, complementary to the recent interesting vertical heterostructures with horizontal atomic layers.