Coplanarity Index for Potential Slip Systems Predicting in Plastic Semiconductors

Despite growing interest in room-temperature plastic semiconductors, understanding and predicting slip modes in semiconductors remains a fundamental challenge due to their complex, low-symmetry structures. Applying analytical frameworks of metal plasticity to semiconductors directly can lead to the ignorance of the quasi-coplanarity in semiconductors due to their complex structures. In this work, we introduce a geometric-descriptor guided strategy to identify potential operative slip systems in semiconductors. A coplanarity index (CI) is developed to quantitatively characterize the quasi-aligned nature of atomic planes. The applicability of the CI is demonstrated in high-performance plastic thermoelectric material Mg₃Sb₂. A quasi-aligned pyramidal plane (Formula presented.) with high CI value in hexagonal Mg₃Sb₂ is predicted to be the active slip plane for 〈c + a〉 dislocation slip, accommodating plastic deformation along the c-axis, which is a mechanism that has not been previously recognized in hexagonal semiconductors. The CI values of the (Formula presented.) planes also reflect the differences in the atom configurations among the isostructure AB₂X₂ Zintl phases, which indicates the good plasticity of Mg₃Sb₂ from the perspective of coplanarity. This geometry-energy integrated framework offers a quantitative methodology for understanding and designing ductile functional semiconductors.