Exotic topological phonon modes in semiconductors: Symmetry analysis and first-principles calculations for representative examples

Nowadays, it is recognized that semiconductors are prospective candidates for promising thermoelectric materials and the gapless topological phonon modes can result in a high phonon scattering rate. Therefore it is necessary to identify the topological phonons in semiconductors, which will aid future research aimed at gaining a better understanding of the thermoelectric properties of semiconductors. Using first-principles calculations and symmetry analysis, we propose a series of semiconductors as excellent candidates for the presence of exotic topological phonons. Remarkably, almost all the types of topological phonons, including various cases of Weyl/Dirac/triple point phonons, sextuple point phonons, nodal line phonons with different shapes and degenerates, and one-, two-, and three-nodal surface phonons can be observed in the phonon curves of these proposed semiconductors, revealing the ubiquitous existence of topological phonon modes in semiconductors. Moreover, the diverse types of topological phonons induce rich types of phononic surface modes in the surface orientations of semiconductors, which is advantageous to surface physics research.