First-principles study of the phase competition, mechanical and piezoelectric properties of pseudo-binary (SiC)(AlN) alloy

TL;DR

This study uses first-principles calculations to explore the phase stability, mechanical, and piezoelectric properties of the (SiC)(AlN) alloy across all compositions, aiming to identify promising materials for piezoelectric applications.

Contribution

It provides a comprehensive first-principles analysis of the phase competition and piezoelectric properties of the (SiC)(AlN) alloy, including predictions of relevant crystalline phases and their properties.

Findings

Wurtzite, zincblende, and rhombohedral phases are the main relevant phases.

Identified compositions with optimal piezoelectric response and acoustic velocity.

Trends and trade-offs relevant for BAW filter applications.

Abstract

The ongoing search for new piezoelectric materials offering adequate balance between piezoelectric response and other application-relevant properties has lead to the investigation of various alloy systems. In this work we study the alloy of the widely used AlN with SiC for their relative abundance, current use in other electronics applications and expected phase competition between wurtzite and other polymorphs, the kind of which has lead to some of the most interesting results notably between AlN and ScN. Here the pseudo-binary (SiC)(AlN) alloy is studied from first-principles over the entire composition range. Relevant crystalline phases are identified using the First-Principles Random Structure Sampling approach which, in accordance with previous bulk experiments, finds wurtzite, zincblende and rhombohedral phases to be the only statistically relevant phases of the alloy. Further study of these phases is done through Special Quasi-random Structures (SQS) and, in the case of the wurtzite phase, predictions of the stiffness, piezoelectric and dielectric tensors. Analysis of these tensors is done through the scope of a Bulk AcousticWave (BAW) filter application, where trends and trade-offs between the c-axis acoustic velocity and piezoelectric response enable identification of relevant compositions.