Piezoelectric properties in hydrofluorination surface-engineered two-dimensional ScN

Abstract

In this work, the electronic, optical, and piezoelectric properties of ScN and F-ScN-H monolayers were investigated by density functional theory. The bandgap of the ScN monolayer changed from 2.05 eV to 4.07 eV upon hydrofluorination. The optical transition from occupied states to empty states occurs at higher energies in the F-ScN-H monolayer compared with ScN due to its higher bandgap. The static dielectric value of ScN was achieved at 2.46 and 2.62 when E||x and E||z, respectively whereas the F-ScN-H monolayer revealed lower dielectric constants of 1.88 and 1.82 when E||x and E||z. The piezoelectric coefficient of e11 was obtained larger for ScN (84.64 × 10−12 C/m) compared to F-ScN-H (18.71 × 10−12C/m) in the relaxed-ion scheme and the piezoelectric coefficient of d11 follows a similar pattern to e11 for these two monolayers. The F-ScN-H monolayer shows the piezoelectric coefficient of e31 and d31 of 26.45 × 10−12C/m and 0.35 p.m./V, respectively in the relaxed-ion scheme.