Research on the modulation of GaN/AlN superlattice thermal transport by phonon wave effects

Abstract

The high integration and miniaturization of semiconductor devices have led to characteristic lengths comparable to the wavelength of phonons. Coherent phonons play a significant role in the thermal management of devices. The controllability of the secondary periodicity in superlattice structures offers a pathway for manipulating phonon waves. In this work, the phonon wave heat conduction in GaN/AlN superlattice is investigated using the transfer matrix method. By constructing the phonon dispersion and transmission of the superlattice, the effects of phonon tunneling, non-reciprocity, and resonance on thermal transport are analyzed based on the consideration of the acoustic wave propagation. It is found that the secondary periodicity of the superlattice introduces band gaps at the center and edges of the Brillouin zone in the dispersion, leading to a rapid decrease in phonon transmissivity and the formation of stop bands. The phonon transport in the superlattice is promoted with the increase of interface density due to the enhancement of phonon tunneling effect and phonon group velocity. Furthermore, the phonon non-reciprocal and resonant effects are also found to effectively regulate the thermal transport in the superlattice. The amplitude of elastic waves in superlattice exhibits non-reciprocal effects, allowing for the lossless transmission of topologically protected phonons. Besides, the phonon resonance enables the transmissivity of phonon within the stop band approaching 1 for multi-superlattice systems. This work provides valuable insights into the changes in thermal conductivity of superlattice structures and offers theoretical guidance for the design of semiconductor devices and the manipulation of phonons.