Epitaxial Sc$_x$Al$_{1-x}$N on GaN is a High K Dielectric

TL;DR

This study demonstrates that epitaxial Sc$_x$Al$_{1-x}$N thin films on GaN exhibit significantly higher dielectric permittivity than AlN, making them promising high-k dielectric materials for electronic and photonic devices.

Contribution

The paper reports the discovery of high dielectric permittivity in epitaxial Sc$_x$Al$_{1-x}$N films, surpassing existing nitrides, and highlights their potential as in situ deposited dielectric layers.

Findings

Dielectric permittivity of 17 to 21 measured at 500 kHz.

Sc$_x$Al$_{1-x}$N has the highest permittivity among nitrides.

Epitaxial growth on GaN enables integration into electronic devices.

Abstract

Epitaxial Sc$_x$Al$_{1-x}$N thin films of ~100 nm thickness grown on metal polar GaN exhibit significantly enhanced relative dielectric permittivity ($\epsilon_r$) values relative to AlN. $\epsilon_r$ values of ~17 to 21 for Sc contents of 17 to 25% (x=0.17 to 0.25) measured electrically by capacitance-voltage (CV) measurements at 500 kHz frequency indicate Sc$_x$Al$_{1-x}$N has the largest relative dielectric permittivity of any existing nitride material. This points toward the usage of Sc$_x$Al$_{1-x}$N as potential epitaxial, single-crystalline dielectric material that can be deposited in situ on GaN and AlN electronic and photonic devices for enhanced performance.