Abstract:

In this paper, bandgap tuning of C₃N through the stacking pattern, layer number, and external electric field were investigated by employing first-principles density functional theory (DFT) calculations. Four stacking structures—namely AA-1, AA-2, AB-1, and AB-2—were investigated in our study; the calculation results showed that the AB-2 structure was the most energetically favorable. Accurate calculations of the bandgap by the HSE06 hybrid functional revealed a large bandgap difference between the C₃N bilayers with AA and AB stacking; specifically, structures with AA stacking had much smaller bandgap than those with AB stacking. Moreover, we found that the bandgap of C₃N decreases from 1.21 eV for a single layer to 0.69 eV for the AB-2 bulk structure. By applying a vertical electric field, the bandgap of a C₃N bilayer, tri-layer, and four-layer with AB-2 stacking can be tuned to a nearly metallic state.

Key words: first-principles calculations, C₃N, stacking, bandgap tuning