Band mapping of in situ Cs intercalated transition metal dichalcogenides

The valence band structure of in situ Cs intercalated layered transition metal dichalcogenides has been studied with photoemission spectroscopy. The intercalation was achieved by room temperature deposition of Cs onto clean sample surfaces in UHV. The changes in the valence band structure upon intercalation were more extensive than predicted by the rigid band model, with the most profound change being a 3D-to-2D transition of the valence band. The band gaps of structurally similar and iso-electronic semiconducting samples were differently affected by the intercalation; in TiS2 the gap was significantly widened, while in ZrSe2 a slight decrease was observed. Very good overall agreement was found when comparing the experimental results with self-consistent LAPW band calculations.