  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.
