Synthesis and electronic properties of InSe bi-layer on Si(111)

Highlights: • InSe forms bi-layer structure on the initial deposition stage on Si(111) surface. • Strong interaction of InSe bi-layer with the substrate leads to charge transfer. • Mexican-hat shape of the valence band is eliminated due to charge transfer. In this paper, we report on the transient phase that forms at the initial stages of InSe growth on Si(111) surface. Using scanning tunneling microscopy and angle resolved photoemission spectroscopy observation and density-functional-theory (DFT) calculations we found that it consists of In-Se bi-layer that is half of the authentic InSe quadruple layer (QL). It has indirect band gap of $~$1.2 eV and the parabolic shape of the valence band in contrast to the Mexican-hat shape of the valence band observed for InSe QL. Parity analysis of the valence bands suggests inversion of the Se $p_z$ and $p_{x,y}$ orbitals near the $\overline{\Gamma }$ point. We attribute the observed features of the InSe valence bands to the charge transfer from the InSe bi-layer to the Si(111) substrate.