Short-range order in semiconductor alloys: does it exist or matter?

Chemical short-range order (SRO) in alloys refers to a statistical deviation from a random distribution of atoms in lattice within a short atomic distance. Although SRO has been linked to important properties in metallic alloys and ceramics, its existence and relevance in semiconductor alloys have remained virtually unknown. In early studies we predicted SRO in group IV semiconductor alloys and the induced significant change in electronic and topological properties. Through synergistic efforts combining advanced characterization including 4D-STEM, APT, and EXAFS and our recently developed machine-learning potential, we have explicitly demonstrated the existence and relevance of SRO in group IV alloys. Extending our theoretical development to III-nitrides alloys, we find atomic ordering carries a contrasting form but significantly impacts piezoelectric and ferroelectric properties. The substantial change in properties thus calls for the need for investigating potential routes for controlling SRO to harness novel properties via SRO engineering.