Topological effects of phonons in GaN and AlGaN: A potential perspective for tuning phonon transport

Abstract

Tuning thermal transport in semiconductor nanostructures is of great significance for thermal management in power electronics. With excellent transport properties such as ballistic transport immune to point defects and backscattering forbidden, topological phonon surface states show remarkable potential in addressing this issue. Herein, topological phonon analyses are performed on hexagonal wurtzite GaN, as well as other nitrides of the same family, i.e. AlN, and AlGaN alloy in perspective of topological phonon phase transition. With the aid of first principle calculations and topological phonon theory, Weyl phonon states, which host surfaces states without backscattering are investigated for all these materials. The results show that there is no nontrivial topological phonon state in GaN. However, by introducing Al atoms, i.e. in wurtzite type AlN and AlGaN, more than one Weyl phonon points are found, confirmed by obvious topological characteristics, including non-zero topological charges, source/sink in Berry curvature distributions, surface local density of states and open surface arcs. As AlN and AlGaN are typical materials in AlGaN/GaN heterostructure based power electronics, existence of topological phonon states in them will benefit thermal management by designing one-way interfacial phonon transport without backscattering.

Million-scale data integrated deep neural network for phonon properties of heuslers spanning the periodic table

“…Moreover, the concept of topological quantum states has recently been introduced to phonon systems 27 . Among them, Weyl semimetals in three dimensions are found in realistic materials 28,29 . Weyl points (WPs) are crossing points of two phonon bands, which can be described by the chiral Weyl equation.…”

Phononic linear and quadratic nodal points in monolayer XH (X=Si, Ge, Sn)

“…Recently, in parallel with electrons, the topology concept is extended to bosonic systems, such as the phonons in crystalline materials [15][16][17][18][19][20][21], classical elastic waves in macroscopic artificial phononic crystals [22][23][24], and magnons in magnets [25]. Of particular importance are the topological phonons in crystalline materials, which are induced by the vibrations of atoms, giving rise a potential perspective to tune the thermal transport [26,27], electron-phonon interactions, phonon devices for thermal diodes, thermal transistors, thermal logic gates and thermal memory [27,28]. It needs to be emphasized that the phonons are not limited by the Pauli exclusion principle, suggesting that experimental probing could proceed in the whole frequency zone of the phonon spectrum.…”

Degenerate topological line surface phonons in quasi-1D double helix crystal SnIP

“…Furthermore, time-reversal symmetry is hard to break in phononic systems, and consequently, this extra symmetry requirement is automatically satisfied in phonons. These advantages have led to a recent surge of interest in characterising topological properties of phonons [5][6][7]21,22,[60][61][62][63][64][65][66][67][68][69][70][71][72][73][74][75][76] , but degenerate lines in surface phonon states have not yet been reported.…”