Fig. 4: Bandgap and effective carrier mass.
From: Prediction of highly stable 2D carbon allotropes based on azulenoid kekulene

The effective mass of electrons (solid shapes) and holes (with the negative sign, empty shapes) is shown for semiconducting azulenoid kekulene carbons (AKC), porous azulenoid kekulenes (PAK), and porous graphenes (PG). Note that the effective mass x-axis is a linear-logarithmic scale: it is linear in the [ − 0.1,0.1] interval and logarithmic outside this interval.