Piezoelectric effect in 2H and 3R phases of α-In2Se3

Abstract

α-In2Se3 is a two-dimensional (2D) ferroelectric semiconductor at RT. Here we study piezoelectric d 33 coefficients in 2H and 3R phases of α-In2Se3 single crystals at RT. Dynamic displacement signals measured with a laser Doppler vibrometer increase linearly with applied electric fields, consistent with the inverse piezoelectric effect. The estimated d 33 coefficients are about 50 pm V−1 in the 2H phase and about 10 pm V−1 in the 3R phase. These d 33 values in α-In2Se3 are large among 2D piezoelectric materials reported before. The slightly larger d 33 value in the 2H phase could be attributed to the stacking structure with in-plane rotation, which allows the 2D layers to move more easily in the perpendicular direction.