First-principles modeling of zincblende AlN layer in Al-AlN-TiN multilayers

TL;DR

This study uses first-principles calculations to investigate the growth mechanism of metastable zincblende AlN in multilayers, revealing it is kinetically driven rather than thermodynamically stable.

Contribution

It demonstrates that zincblende AlN formation is a kinetically driven process, challenging thermodynamic explanations and providing insights into its growth mechanism.

Findings

Zincblende AlN is not thermodynamically stable under epitaxial strain.

Formation of zincblende AlN is kinetically driven, not thermodynamically favored.

Comparison of formation energetics shows kinetic factors dominate in growth.

Abstract

An unusual growth mechanism of metastable zincblende AlN thin film by diffusion of nitrogen atoms into Al lattice is established. Using first-principles density functional theory, we studied the possibility of thermodynamic stability of AlN as a zincblende phase due to epitaxial strains and interface effect, which fails to explain the formation of zincblende AlN. We then compared the formation energetics of rocksalt and zincblende AlN in fcc Al through direct diffusion of nitrogen atoms to Al octahedral and tetrahedral interstitials. The formation of zincblende AlN thin film is determined to be a kinetically driven process, not a thermodynamically driven process.