THE ELECTRONIC-STRUCTURE OF ZRSE2 AND CSXZRSE2 STUDIED BY ANGLE-RESOLVED PHOTOELECTRON-SPECTROSCOPY

We report an angle-resolved photoelectron spectroscopy study of the layered semiconductor ZrSe2, and of changes in its electronic structure induced by in situ intercalation with Cs. The results show that the valence band structure of ZrSe2 is initially of 3D character, but is transformed to become essentially 2D upon Cs intercalation. The observed changes are supported by self-consistent LAPW band calculations, and are not compatible with the rigid-band model. Changes in the Se 3d core level lineshape are attributed to an intercalation-induced increase in the carrier density in the lowest conduction band, which produces a different screening of the core hole.