Defects induced changes in conduction bands of HfS₂

We report on a comprehensive study of the electronic structures of the layered semiconductor 1T-HfS2 by employing angle-resolved photoemission spectroscopy (ARPES). With in-situ potassium doping, the band structures of HfS2 could be tuned, and both of the valence band and the conduction band could be observed. S vacancy defects could be induced by post-annealing of HfS2 and a certain amount of S vacancies would result in a peculiar change of the conduction band at M over bar point- the fracture of the conduction band bottom. Our results could provide key information for the defect studies and the application of HfS2.