Band structure of an epitaxial thin film of InSe determined by angle-resolved ultraviolet photoelectron spectroscopy

The valence band structure of a very thin film (about 6.4 nm thick) of the layered semiconductor InSe grown by molecular beam epitaxy onto a Si(111)1×1-H substrate has been determined by angle-resolved ultraviolet photoelectron spectroscopy using synchrotron radiation. The dispersion curves along the two symmetry directions of the Brillouin zone in the plane of the layers have been obtained from the angular dependence of the valence band spectra. Those along the normal to the plane of the layers have been derived from normal emission at various photon energies. It is shown that the experimental dispersion curves obtained are in very good agreement with the electronic band structure calculated for InSe bulk material of the ? polytype, in agreement with the crystalline structure of the film.