This study was meticulously
conducted, delving into the epitaxial
growth of nanothin β-In2Se3 films on sapphire
(0001) using molecular beam epitaxy. The growth temperature was carefully
set at 480 °C, and the selenium to indium flux ratio (R
Se/In) was systematically varied from 1 to 100.
The phase transformation from γ-In2Se3 to β-In2Se3 was precisely controlled
by manipulating the R
Se/In and confirmed
through Raman scattering measurements and synchrotron-based grazing-incidence
wide-angle X-ray scattering. The surface morphology for various R
Se/In of In2Se3 was analyzed
by atomic force microscopy (AFM). The lowest surface roughness is
around 0.58 nm, which is achieved under the R
Se/In = 60 growth condition. The nanothin β-In2Se3 film with a layer-by-layer atomic arrangement was
verified by high-resolution transmission electron microscopy. According
to the experimental results, the growth dynamics of In2Se3 are proposed to be step-flow growth and horizontal
growth under R
Se/In 45 and 60 conditions,
respectively. This research underscores the control of the growth
mechanism by Se/In flux and its role in facilitating the In2Se3 epitaxy for integration in the development of 2D-materials-based
future electronic devices.