Alloy Stabilized Wurtzite Ground State Structures of Zinc-Blende Semiconducting Compounds

TL;DR

This study demonstrates that alloying can stabilize the wurtzite phase over the zinc-blende phase in certain semiconducting compounds, revealing a novel pathway for phase stabilization through alloying.

Contribution

It introduces a new concept that alloying can stabilize the wurtzite structure, which is distinct from the parent phases, supported by first-principles calculations.

Findings

Wurtzite alloys have lower strain energy and formation enthalpy than zinc-blende alloys.

Certain alloy compositions favor the wurtzite structure over zinc-blende.

First example of an alloy adopting a structure different from both parent phases.

Abstract

The ground state structures of the A$_x$B$_{1-x}$C wurtzite (WZ) alloys with $x=$0.25, 0.5, and 0.75 are revealed by a ground state search using the valence-force field model and density-functional theory total energy calculations. It is shown that the ground state WZ alloy always has a lower strain energy and formation enthalpy than the corresponding zinc-blende (ZB) alloy. Therefore, we propose that the WZ phase can be stabilized through alloying. This novel idea is supported by the fact that the WZ AlP$_{0.5}$Sb$_{0.5}$, AlP$_{0.75}$Sb$_{0.25}$, ZnS$_{0.5}$Te$_{0.5}$, and ZnS$_{0.75}$Te$_{0.25}$ alloys in the lowest energy structures are more stable than the corresponding ZB alloys. To our best knowledge, this is the first example where the alloy adopts a structure distinct from both parent phases.