Figure 4

Angle-resolved photoemission spectroscopy of low and highly doped films.

Band structures obtained along the K–Γ–K direction and energy distribution curves along  = 0 for Dy-doped samples with (a,c), x = 0.055 and (b,d), x = 0.113, measured at 20 K and 300 K, respectively. Note that the arrows indicate the relative locations of the Dirac points in the band structure and energy distribution curves. The measurements reveal strong spectral intensities at the DPs in the TSS up to 300 K for samples with x ≤ 0.055, however, for samples with x = 0.113, a gap on the order of ~85 meV was consistently detected in band structure and EDC plots. These sizeable gaps persist in measurements performed at room temperature.