HfS₂ (Hafnium Disulfide)

A layered van der Waals transition-metal dichalcogenide with the 1T (octahedral) structure, space group P3̄m1. It is an indirect-bandgap semiconductor (~2 eV) exhibiting high theoretical carrier mobility and a strong photoresponse, making it attractive for field-effect transistors, photodetectors, and other two-dimensional optoelectronic devices. Its relatively large bandgap and environmental sensitivity (surface oxidation) distinguish it within the TMD family, and it serves as a model system for studying group-IV dichalcogenide electronics and dielectric applications.