  Heterostacks formed by combining two-dimensional materials show novel
properties which are of great interest for new applications in electronics,
photonics and even twistronics, the new emerging field born after the
outstanding discoveries on twisted graphene. Here, we report the direct growth
of tin nanosheets at the two-dimensional limit via molecular beam epitaxy on
chemical vapor deposited graphene on Al2O3(0001). The mutual interaction
between the tin nanosheets and graphene is evidenced by structural and chemical
investigations. On the one hand, Raman spectroscopy indicates that graphene
undergoes compressive strain after the tin growth, while no charge transfer is
observed. On the other hand, chemical analysis shows that tin nanosheets
interaction with sapphire is mediated by graphene avoiding the tin oxidation
occurring in the direct growth on this substrate. Remarkably, optical
measurements show that the absorption of tin nanosheets show a graphene-like
behavior with a strong absorption in the ultraviolet photon energy range,
therein resulting in a different optical response compared to tin nanosheets on
bare sapphire. The optical properties of tin nanosheets therefore represent an
open and flexible playground for the absorption of light in a broad range of
the electromagnetic spectrum and technologically relevant applications for
photon harvesting and sensors.
