Quasi van der Waals Epitaxy of Rhombohedral-stacked Bilayer WSe2 on GaP(111) Heterostructure

TL;DR

This paper demonstrates the epitaxial growth of rhombohedral-stacked bilayer WSe2 on GaP(111) substrates, confirming its structure and electronic properties, and opening avenues for device applications leveraging 2D/3D heterostructures.

Contribution

It reports the first molecular beam epitaxy growth of rhombohedral-stacked bilayer WSe2 on GaP(111), with structural and electronic characterization confirming its properties.

Findings

Successful epitaxial growth of rhombohedral WSe2 bilayer on GaP(111)

Confirmation of 3R-stacking via STEM and Raman spectroscopy

ARPES reveals the expected valence band structure with maximum at gamma point

Abstract

The growth of bilayers of two-dimensional (2D) materials on conventional 3D semiconductors results in 2D/3D hybrid heterostructures, which can provide additional advantages over more established 3D semiconductors while retaining some specificities of 2D materials. Understanding and exploiting these phenomena hinge on knowing the electronic properties and the hybridization of these structures. Here, we demonstrate that rhombohedral-stacked bilayer (AB stacking) can be obtained by molecular beam epitaxy growth of tungsten diselenide (WSe2) on gallium phosphide (GaP) substrate. We confirm the presence of 3R-stacking of the WSe2 bilayer structure using scanning transmission electron microscopy (STEM) and micro-Raman spectroscopy. Also, we report high-resolution angle-resolved photoemission spectroscopy (ARPES) on our rhombohedral-stacked WSe2 bilayer grown on GaP(111)B substrate. Our ARPES measurements confirm the expected valence band structure of WSe2 with the band maximum located at the gamma point of the Brillouin zone. The epitaxial growth of WSe2 on GaP(111)B heterostructures paves the way for further studies of the fundamental properties of these complex materials, as well as prospects for their implementation in devices to exploit their promising electronic and optical properties.