Identification of short-range ordering motifs in semiconductors.

Chemical short-range ordering is expected to be a key factor for tuning the electronic structure of semiconductors. However, experimental evidence of short-range ordering is still lacking due to the challenge of characterizing atomic-scale ordering motifs. Here, we determined the presence of short-range order in a ternary GeSiSn semiconductor system using advanced energy-filtered four-dimensional scanning transmission electron microscopy and large-scale atomistic models generated by a machine learning neuroevolution potential of first-principles accuracy. This approach revealed preferred ordering of different atomic species with the dominant occurrence of Si–Ge–Sn triplets. Our findings not only confirmed the presence of short-range order but also directly revealed the actual atomic structure, demonstrating the potential for informed atomic order–based band engineering as a third degree of freedom beyond composition and strain tuning. Editor's summary: Short-range order (SRO) refers to the tendency of atoms to arrange themselves in a crystal lattice over small distances (typically less than a few nanometers) without forming a fully ordered compound at long ranges. SRO in metals has been linked to properties of mechanical deformation, and in ceramics has been linked to properties related to diffusion. In semiconductors, the concept of SRO has only rarely been studied beyond theoretical predictions linking SRO to important changes in electronic band structure. Using energy-filtered electron microscopy and complementary simulations, Vogl et al. confirmed the presence of SRO in a germanium-silicon-tin semiconductor and identified the actual atomic structure of the SRO motifs. Their work explores an exciting area for understanding and controlling SRO in semiconductors. —Yury Suleymanov [ABSTRACT FROM AUTHOR]