Angle-resolved photoemission studies of the band structure of Ti Se 2 and Ti S 2

摘要: The electronic structure of high-quality Ti${\mathrm{Se}}_{2}$ and Ti${\mathrm{S}}_{2}$ crystals has been investigated using angle-resolved photoemission with HeI, HeII, NeI resonance radiation. Results compare well recent self-consistent energy-band calculations although differences occur which may be due to the three- rather than two-dimensional nature specific bands. Occupied $d$ states at zone edge are observed in both materials. A small overlap $\frac{s}{p}$ valence band $\ensuremath{\Gamma}$ is case approximate agreement other workers. appears a defect semiconductor gap 0.3 \ifmmode\pm\else\textpm\fi{} 0.2 eV.