Surface Piezoelectricity of (0001) Sapphire

TL;DR

This study reveals that the (0001) surface of sapphire exhibits significant piezoelectricity due to broken symmetry, making it potentially useful for technological applications in electronics, catalysis, and quantum devices.

Contribution

First principles calculations demonstrate that sapphire's (0001) surface is piezoelectric, unlike its bulk, highlighting a novel surface property with technological relevance.

Findings

Surface of sapphire is piezoelectric due to broken symmetry.

Surface piezoelectric response is comparable to bulk materials.

Potential applications in electronics and catalysis.

Abstract

Interfaces of sapphire are of technological relevance as sapphire is used as a substrate in electronics, lasers, and Josephson junctions for quantum devices. In addition, its surface is potentially useful in catalysis. Using first principles calculations, we show that, unlike bulk sapphire which has inversion symmetry, the (0001) sapphire surface is piezoelectric. The inherent broken symmetry at the surface leads to a surface dipole and a significant response to imposed strain: the magnitude of the surface piezoelectricity is comparable to that of bulk piezoelectrics.