Valence and conduction band structure of the quasi-two-dimensional semiconductor Sn S2

We present the momentum-resolved photoemission spectroscopy of both the valence and the conduction band region in the quasi-two-dimensional van der Waals-layered indirect band gap semiconductor SnS2. Using a combination of angle-resolved ultraviolet photoemission and angle-resolved two-photon photoemission (AR-2PPE) spectroscopy, we characterize the band structure of bulk SnS2. Comparison with density functional theory calculations shows excellent quantitative agreement in the valence band region and reveals several localized bands that likely originate from defects such as sulfur vacancies. Evidence for a moderate density of defects is also observed by AR-2PPE in the conduction band region, leading to localized bands not present in the computational results. The energetic structure and dispersion of the conduction bands is captured well by the computational treatment, with some quantitative discrepancies remaining. Our results provide a broader understanding of the electronic structure of SnS2 in particular and van der Waals-layered semiconductors in general.