High-resolution angle-resolved photoemission study of layered transition-metal dichalcogenides Nb1-xTixXc2 (Xc = S, Se, Te)

High-resolution angle-resolved photoemission spectroscopy (ARPES) has been performed on Nb1-xTixXc2 (Xc = S, Se, Te) to elucidate the change in the band structure as a function of x and Xc. We found that spectral intensity near EF of S- and Se-based compounds is remarkably suppressed, suggesting the strong scattering of electrons by the substitution of transition metals. In contrast, Te-based compound shows a clear Fermi edge. We discuss the origin of metal-semiconductor transition in terms of the strength of hybridization between chalcogen p band and transition metal d band