Transition from Semimetal to Semiconductor in ZrTe₂ Induced by Se Substitution

Two-dimensional layered transition-metal telluride can build stable metallic, metastable metallic, or semimetallic polymorphic crystal structures with enormous technological and scientific applications. Herein the hexagonal structures of zirconium ditelluride (ZrTe₂) and ZrTe_2(1-Se₂ (0 ≤ x ≤ 1) single crystals were selectively synthesized through the chemical vapor transport method. The electronic band structures were systematically studied through angle-resolved photoemission spectroscopy (ARPES) combined with first-principles density functional theory (DFT) calculations. The ARPES results suggested a clear electronic phase transition from a semimetal to a semiconductor in ZrTe_2(1-Se₂ with the x value changing. Compared with pristine ZrTe₂, the valence band splitting in ZrTe_2(1-Se₂ decreased at the Γ point due to the reduction of the spin-orbit interaction, whereas an indirect band gap opened in the vicinity of the Fermi level with the increase in Se concentration. Our DFT calculations further confirmed that the substituted Se atoms on Te sites could affect the band structure of ZrTe₂ to induce a distinct transition from semimetal to semiconductor, suggesting their high potential for valleytronics applications.