Hafnium Diselenide (1T-HfSe₂)

HfSe₂ is a Group-IV transition metal diselenide whose stable phase is the 1T phase (octahedral, CdI₂-type), adopting a trigonal structure with space group P-3m1. Unlike 2H-phase TMDs such as MoS₂, 1T-HfSe₂ is an indirect-bandgap semiconductor with a bandgap of about 1.1–1.2 eV, close to that of silicon, and its conduction- and valence-band edge positions make it suitable as a channel material for CMOS-compatible field-effect transistors (FETs). It offers relatively high carrier mobility, and its native oxide (HfO₂) can serve as a gate dielectric, making it attractive for low-power two-dimensional electronic devices. Its drawback is sensitivity to air and susceptibility to oxidation, requiring encapsulation for protection.