Figure 1
From: New energy with ZnS: novel applications for a standard transparent compound

Band structure of ZnS for the two different crystal structures, zincblende (left-panel) and wurtzite (right-panel). Blue (orange) dotted lines represent the Fermi level for Al-doped (Cu-doped) ZnS. The valence band maximum of clean ZnS is used as energy scale reference (0 eV) for both lattices.