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

The valence band structure of a very thin him (about 6.4 nm thick) of the l ayered semiconductor InSe grown by molecular beam epitaxy onto a Si(1 1 1)1 x 1-H substrate has been determined by angle-resolved ultraviolet photoele ctron spectroscopy using synchrotron radiation. The dispersion curves along the two symmetry directions of the Brillouin zone in the plane of the laye rs have been obtained from the angular dependence of the valence band spect ra. Those along the normal to the plane of the layers have been derived fro m normal emission at various photon energies. It is shown that the experime ntal dispersion curves obtained are in very good agreement with the electro nic band structure calculated for InSe bulk material of the gamma polytype, in agreement with the crystalline structure of the film.