Effects of iron intercalation on the electronic structures of ZrS₂ and HfS₂

The crystal structure and optical properties have been studied for ZrS₂ and HfS₂ which were intercalated with Fe. X-ray analyses show that Fe atoms enter the tetrahedral sites, keeping the original 1T polytypism, and expanding the inter-layer spacing. Infrared absorption spectra show that the intercalation results in formation of deep impurity states. Direct-band energy gaps, on the other hand, in the visible to ultraviolet region increase with increase in the composition of Fe. This result indicates that intercalation inherently influences the electronic structure of the host material through modification of the inter-layer interactions.