First-principles study on the lattice dynamics of the layered ZnO in comparison with the wurtzite structure

• The phonon dispersions for a layered ZnO are first calculated and compared with wurtzite ZnO;
• The layered ZnO has the thermal-expansion behavior similar to the wurtzite phase, but quite different optical response.
• The Raman peak observed in experiment is assigned to E2ghigh mode of the layered ZnO.

The lattice dynamics of a layered ZnO with α  -BN structure has been studied using first-principles calculations based on density functional theory. The phonon dispersions of the layered ZnO are compared with those of ZnO with wurtzite structure. The phonon frequencies, the first and second derivatives of frequencies vs. pressure, and the corresponding Grüneisen parameters are presented and discussed in comparison with the wurtzite ZnO. The layered ZnO is predicted having the thermal-expansion behavior similar to the wurtzite phase, but quite different optical responses. Compared with the calculated results, the Raman peak observed in experiment is assigned to the E2ghigh mode of the layered ZnO.